Design of RCC Building

Design and Analysis of Pile Foundations

Design and Analysis of Strip Footings

Design and Analysis of Isolated Footings

Importing AutoCAD file to STAAD.PRO

Design of RCC Building

Primavera: Project Management Questionnaire

Primavera P6 (Part-II)

Primavera P6 (Part-I)

Guidelines For Building Design

CHAPTER-I
GENERAL PHILOSOPHY OF BUILDING DESIGN

DESIGN OF R.C.C. MEMBERS OF BUILDINGS, PROCEDURE FOLLOWED IN THE DESIGNS CIRCLE.

• INTRODUCTION:

Instructions about the preparation of R.C.C design of building works have been issued vide Govt. in P.W.D. Circular No.BDG-1080/ 80838 (394)/Desk-2, dt.3rd Nov.1980.

1. This circular states that R.C.C. design of all load bearing structures and R.C.C. framed structures up to four stories i.e. G+3 upper, except in case of structures requiring wind and/or seismic analysis, shall be prepared by the field engineers.
2. The design of R.C.C. frame structures having more than G+3 upper floors as well as structures with more that G+2 upper floors requiring wind and/or seismic analysis are required to be prepared by Design Circle.
3. Designs Circle will undertake the work of preparing R.C.C. design for a structure only after the receipt of the following information from the field engineers.
   (a) Copy of Administrative approval to the estimate of the structure, (based on approved Architectural drawings.) along with a blue print set of original Architect’s plans (No traced copies are acceptable).
   (b) Copy of Technical sanction from the competent authority.
   (c) If the work is budgeted, item number of work and its page number in the Budget Book.
   (d) Proposed construction programme i.e. proposed dates of start of different stages of construction and scope of different phases of construction, in case of phased construction.
   (e) “Field Data” in standard proforma prescribed by the Designs Circle. Copy of the standard proforma is kept at page 48 .
4. It is also desired that Field Engineer should communicate to Designs Circle, the present position of the tender for the work i.e. the date of issue of tender notice, date of receipt of the tender and likely date of issue of work order. This information will be helpful to Designs Circle, in planning the design work and there will be less likelihood of delay in supply of R.C.C. Schedules from time to time i.e. as per the construction programme proposed by field engineers.
5. It is a prerequisite that, before undertaking actual design work, the design engineer should have basic knowledge of “Strength of materials”, “Properties of materials”, “Behaviour of structures,”, “Analysis of structures” and thorough knowledge about detailing of reinforcement, etc. Also he should be acquainted with various I.S. Codes which are required to be referred to in the design work. It is, therefore, advised that the designer should refresh his knowledge by referring to the various technical books and codes.

• DESIGN PHILOSOPHY :

1. R.C.C. design of building is being carried out mainly (1) Limit state method.
2. The Limit state method is now in vogue in all government design offices and premier private consulting firms. The B.I.S. have published I.S.:456-2000 incorporating the use of Limit State Method as a main philosophy of design. The designer should therefore get well versed with the theory of Limit State Method of design.
   Working Stress Method: Used over decades, this method is now practically outdated in many advanced countries of the world, because of its inherent limitations.
   The I.S.:456-2000 code gives emphasis on Limit State Method which is the modified form of Ultimate Load Method.
   Limit State Method is a judicious amalgamation of Working Stress Method and Ultimate Load Method, removing the drawbacks of both the methods but retaining their good points. It is also based on sound scientific principles and backed by more than 25 years of research. The Limit State Method has proved to have an edge over the Working Stress Method from the economic point of view. Consequently we need not stick to Working Stress Method any more. Accordingly, Designs Circle in P.W. Department is designing the R.C.C. structures as per Limit State Method, since early eighties.
   
3. Codes: In carrying out the design calculations, one has to comply to the provisions of various I.S. Codes. Use of special publications of B.I.S. and Hand Books for design methodology and readymade design tables can also be made. A List of frequently referred codes/hand books is given on page 7.
   
4. The designer is advised to study I.S. codes carefully and also discuss the provisions among his colleagues/superior officers for clarification/s for better understanding.
   
5. Besides analytical part of structural design, following factors should also be kept in mind while designing the structure.
   (a) Strength of structure.
   (b) Durability of structure.
   (c) Serviceability of structure, during construction as well as during design life time of the structure.
   (d) Economy in building materials ease of construction and maintenance.
   (e) Economy in centering and form work.
   (f) Aesthetics of structure.

• COMPUTER AIDED DESIGN :
  

1. Personal computers of sufficiently high speed and large memory capacity have been made available to Designs Circle. Designs Circle has developed various design software and same are being used. Software available presently in Designs Circle are discussed in Chapter IV. Designer should get conversant with the Users Manuals of these programmes so that he can work independently on the computer.
   At present mainly STAAD. Pro /Struds are being used for design of buildings in Designs Circle.
   

• STEPS INVOLVED IN R.C.C. DESIGN :
  The R.C.C. design of a building is carried out in following steps:
  (i) Study the architectural drawings.
  (ii) Study the field data.
  (iii)Prepare R.C.C. layouts at various floor levels.
  (iv) Decide the imposed live load and other loads such as wind, seismic and other miscellaneous loads, (where applicable), as per I.S.:875, IS 1893-2000 considering the contemplated use of space, and seismic zone of the site of proposed building.
  (v) Fix the tentative slab and beam sizes and then prepare preliminary beam design. Using values of support reactions from preliminary beam design, prepare preliminary column design and based on these load calculations, fix tentative column section and it’s concrete mix. As far as possible, for multistoried buildings, the same column size and column mix should be used for at least two stories so as to avoid frequent changes in column size and concrete mix facilitate easy and quick construction. Concrete Mix to be adopted for beams and slabs as per IS :456-2000 page No.20.
  (vi) Group the members such as columns, beams, slabs, footings etc. wherever possible, on the basis of the similarity of loading pattern, spans, end conditions etc. It reduces the quantum of calculation work. (vii) Prepare R.C.C. Layouts and get approval from the Architect to the R.C.C. layouts and tentative sizes of beams and columns and other structural members if any. In the R.C.C. layouts, show the structural arrangement and orientation of columns, layout of beams, type of slab (with its design live load) at different floor levels.
  For a building, generally following R.C.C. layouts are prepared.
  (a) R.C.C. layout at pile cap/plinth level/tie level (if any).
  (b) R.C.C. layout at various floor levels or at typical floor level (depending on Architectural plans).
  (c) R.C.C. layout at terrace level.
  (d) R.C.C. layout at staircase roof level.
  and where lifts are provided.
  (e) R.C.C. layout at lift machine room floor level.
  (f) R.C.C. layout at lift machine room roof level.
  Where good foundation is available at reasonably shallow depth, provision of plinth beams in Non Seismic Areas can be omitted. However, this should be got approved from Superintending Engineer/competent authority. In such case the R.C.C. layout at plinth level may be prepared accordingly.
  (viii) Finalise various structural frames in X-direction and Y-direction followed by preparation of frame sketches and filling in, data of the frames on coding sheets, for computer aided frame analysis.
  (ix) Feed the data of frames on computer and recheck the data so stored, by getting a print out.
  (x) Analyse the frames using STAAD Pro.
  (xi) Calculation of Horizontal forces : Whenever the structure is to be designed for horizontal forces (due to seismic or wind forces) refer I.S.:1893 for seismic forces and I.S.:875 Part-III for wind forces.
  All design parameters for seismic/wind analysis shall be got approved from Superintending Engineer before starting design calculations and frame analysis. The proper selection of the various parameters is a critical stage in design process.
  (xii) Design column sections Assemble the design data for column design, using results obtained in analysis of respective X and Y direction frames, which include the column under considerations. The design of column can be done using computer programme “ASP2” or manually by referring to ‘Hand Book of R.C.members (Limit State Design) Volume II’ (Govt. of Maharashtra Publication).
  (xiii) Design footings manually using ‘Hand Book of R.C.C. members (Limit State Design) Volume II’ or by using the computer programme ‘FOOT’ or other suitable programme Software for design of isolated or combined footing. For design of other types of footing refer standard text books.
  (xiv) Design slabs manually by using ‘Hand Book for R.C.members Vol.I’ or by using computer programme ‘SLAB’.
  (xv) Design beams by using the frame analysis output. It gives required area of reinforcement at various locations and diameter and spacing of shear reinforcement. Ductility shall be applied for building in Seismic Zone III & IV above.
  Designer’s work now involves.
  (a) Fix the bar diameter and number of bars (at top and bottom) at various locations along the beam span, as per codal provisions and practice.
  (b) Finalise the diameter and spacing of shear reinforcement as per analysis results and as per codal provisions of detailing where ever applicable.
  (xvi) Preparation of R.C.C. schedules for footings, slabs, beams and columns at various levels, on completion of respective design.
  As these R.C.C. schedules are to be used during the execution, designer should take maximum care in preparing them. Schedules should be prepared by one Engineer, and thoroughly cross checked by another Engineer, before submitting the same for approval to the competent authority. In schedules, special instructions to the field engineers should be highlighted and sketches should be drawn wherever necessary. 

CHAPTER-II
PREREQUISITES OF BUILDING DESIGN

• STUDY OF ARCHITECTURAL DRAWINGS :

1. As the building is to be constructed as per the drawings prepared by the Architect, it is very much necessary for the Designer to correctly visualize the structural arrangement as proposed by the Architect. A Designer, after studying Architect’s plans, can suggest necessary changes like additions / deletions and orientations of columns and beams as required from structural point of view.
2. For this, the designer should have a complete set of prints of original approved architectural drawings of the building namely i) Plans at all the floor levels, ii) Elevations, (front, back and sides), iii) Salient cross sections where change in elevation occurs and any other sections that will aid to visualize the structure more easily. The cross sections should show the internal details like locations of windows, doors, toilets, staircases, lift machine room, staircase rooms, and any other special features like gutter at roof level, projections proposed to give special elevation treatment, etc.
3. During the study following points should be noted. The drawings should be examined to find out,
   (i) Whether the plan shows all the required dimensions and levels so that the designer can arrive at the lengths and sizes of different members. Wherever necessary, obligatory member sizes required by Architect (on architectural grounds) are given or otherwise.
   (ii) Whether the plans and schedules of doors and windows etc. are supplied so as to enable designer to decide beam sizes at these locations.
   (iii) Whether thickness of various walls and their height is given. Head room in stair and ramp, porch basement should be checked with reference of required depth of beam.
   (iv) Whether functional requirements and utility of various spaces are specified in the plans. These details will help in deciding the imposed load on these spaces.
   (v) Whether material for walls is specified.
   (vi) The structural arrangement and sizes proposed by the Architect should not generally be changed except where structural design requirements can not be fulfilled by using other alternatives like using higher grade of concrete mix or by using higher percentage of steel or by using any other suitable alternate structural arrangement. Any change so necessitated be made in consultation with the Architect. Further design should be carried out accordingly.                                           (vii) Note the false ceiling, lighting arrangements, lift/s along with their individual carrying capacity (either passenger or goods), Air Conditioning ducting, acoustical treatment, R.C.C. cladding, finishing items, fixtures, service/s’ opening proposed by the Architect.
   (viii) Note the position/s of expansion joints, future expansion (horizontal and / vertical) contemplated in the Architect’s plan and check up with the present scope of work (indicated in the “Field Data” submitted by the field engineers). The design of the present phase will account for future expansion provision such as loads to be considered for column and footing design (combined / expansion joint footing) resulting if any.
   If this aspect is neglected it will create design as well as execution problems in the next phase of work. In case of vertical expansion in future, the design load for the present terrace shall be maximum of the future floor level design load or present terrace level design load.
   (ix) Whether equipment layout has been given, particularly in the areas where heavy machinery is proposed to be located.
   (x) Special features like sun breakers, fins, built-in cupboards with their sections so as to enable designer to take their proper cognizance.                                                       (xi) Whether the location/s of the over head water tanks specified by the Architect and whether “Field Data” submitted by field engineer furnishes the required capacity of each over head water tank.
   (xii) What type of water proofing treatment is proposed in toilet blocks and on terrace.
   The findings of the above scrutiny should be brought to the notice of the Architect and his clear opinion in this matter should be obtained before proceeding ahead with R.C.C. design.

• STUDY OF FIELD DATA :
  

1. The architectural drawings give the details only from architectural point of view. As such the designer must also have thorough information of the site where the structure is proposed to be constructed. For this a standard proforma has been prescribed by Designs Circle. The field engineer has to submit the field data in this proforma while requesting Designs Circle for supply of R.C.C. designs. Copy of the form of “Field Data” is kept as page 48.
   
2. The “Field Data” is essential before starting design work. However, it is generally noticed, that the “Field Data” lacks vital information such as bearing capacity of the founding strata, proposed location and capacity of over head water tank/s, electrical lift loads, future horizontal and/or vertical expansion etc. So on receipt of “Field Data” it should be checked thoroughly and if any data is found to be missing, the same should be called from field engineer immediately, to avoid delay in starting the design work.
   
3. Besides information on the points mentioned in prescribed proforma, information on special points also is to be supplied where applicable by the field officers, like :    (i) Machinery and/or equipment layout.
   (ii) Air cooling/air conditioning ducting layouts including exhaust arrangements.
   (iii) False ceiling arrangements, proposed acoustical treatment, electrical lighting and audio system fixtures.
   (iv) Fire fighting pipeline/s or any other special ducting layouts.
   (v) Sub soil and sub soil water properties particularly Sulfide and Chloride contents where the building is located in coastal and or highly polluted industrial area.
   (vi) Importance factor (I) and zone factor as per I.S.1893; to be considered for the proposed building when the building is being constructed in seismic zone. It may be noted that the importance factor more than 1.0 leads to increased seismic forces consequently the reinforcement requirement increases considerably. Therefore before starting Seismic Analysis, importance factor (I) should be got approved from the Superintending Engineer.
   (vii) In case foundations other than open type of foundation proposed (with reasons) and safe bearing capacity of the founding strata and its depth from the general ground level alongwith trial bore log details and test results on rock samples.
   (viii) If necessary, Superintending Engineer, Designs Circle shall visit the site, in case of critical site OR field data is inadequate.
   

• LIST OF I.S. CODES GENERALLY REQUIRED TO BE REFFERED TO FOR BUILIDNG DESIGN.
  

1.  The important I.S. Codes (with their latest editions/amendments) to be referred to for design of buildings are as follows :
   (i) I.S.:456-2000 : Code of practice for plain and reinforced concrete.
   (ii) I.S.:800-1962 : Code of practice for use of structural steel in general building construction.
   (iii) I.S.:875-1987 : Design loads (Part I to V) other than earthquake for building design.
   Part-I : Dead loads. Part-II : Imposed loads. Part-III : Wind loads. Part-IV : Snow loads. Part-V : Special loads and load combinations.                                                            (iv) I.S.:1080-1965: Code of practice for Design and construction of shallow foundation in soils (other than Raft, Ring and Shell)
   (v) I.S.: 1642-1988: Fire safety of Bldgs. (General) Details of Construction.
   (vi) I.S.:1643-1988: Code of Practice for Fire safety of Bldgs. (General) Exposure Hazard.
   (vii) I.S.:1644-1988: Code of practice for fire safety of Bldgs. (General) Exit requirements and personal Hazards.
   (viii)I.S.:1888-1972:Methods of load test on soils.
   (ix)I.S.:1893-(Part 1): Criteria for 2002 earthquake resistant design of structures.
   (x) I.S.:1904-1986: Code of practice for design & construction of foundation in soil structural safety of building  foundation.                                                                                  (xi) I.S.:2911:1990: Code of practice (Part I to IV) for design and construction of pile foundation.
   (xii) I.S.:2950-1981: Code of practice for design and construction of raft foundation.
   (xiii) I.S.:3370-1965: Code of practice for water retaining structures.
   (xiv) I.S.:3414-1987: Code of Practice for Design and installation of joints in Buildings.
   (xv) I.S.:4326-1993: Code of practice for earthquake resistant design of structure.
   (xvi) I.S.:6403-1981: Code of Practice for Determination of bearing pressure of shallow foundation.
   (xvii) I.S.:13920-1993: Code of (reaffirmed practice for 1998) ductility detailing of reinforced concrete structures subjected to seismic forces.                                                I.S. Codes are also available for design of special types of structures like folded plate, shell structures etc. Refer Publication list of BIS for the same.
   Similarly there are special publications of I.S. which are useful for design of buildings such as.
   (i) SP-16 : Design Aids to I.S.:456-2000.
   (ii) SP-22 : Explanation of I.S.1893 & I.S.:4326.
   (iii) SP-23 : Concrete Mix.
   (iv) SP-24 : Explanation of I.S.:456-2000.
   (v) SP-25 : Cracks in buildings and their repairs.
   (vi) SP-34 : Detailing in R.C.C. structures.
   (vii) SP-38 : Design of steel trusses.
   Besides above mentioned I.S. Codes “Hand Book for R.C.Members” (Limit State Design) Vol.I.and II by P.L. Bongirwar and U.S.Kalgutkar, published by P.W.D. (Govt. of Maharashtra) is very useful.
   For aspects which are not covered by any other I.S. codes available, relevant British Standard codes may be referred to.
   

• While designing R.C.C. structures, important provisions of I.S.Codes must be borne in mind. Some of the important provisions of I.S.:456-2000 are as follow :          

1. General Provisions : Clause No.20 : Deals with stability of the structure against overturning and sliding. Clause No.26.2.1 : Development length of bars.
   Clause No.26.3.2: Minimum distance between individual bars.
   Clause No.26.3.3: Maximum distance between bars in tension.
   Clause No.26.4 : Nominal Cover to reinforcement.
   Clause No.27 : Expansion joints.
   
2. Provision regarding slabs :
   Clause No.22.2 : Effective span.
   Clause No.22.4.1: Arrangement of Imposed load.
   Clause No.22.5 : Moment and shear co-efficient for continuous beams.
   Clause No.23.2 : Control of deflection.
   Clause No.24.1 : Provisions regarding solid slabs. Clause No.26.5.2.1: Minimum reinforcement.
   Clause No.26.5.2.2: Maximum diameter. 
3. Provisions Regarding Beams :
   Clause No.22.2 : Effective span.
   Clause No.22.4.1: Arrangement of live load.
   Clause No.22.5 : Moment and Shear co-efficient for continuous beams.
   Clause No.23.2 : Control of deflection.
   Clause No.23.3 : Slenderness Limits for beams.
   Clause No.26.5.1.1: Requirement of tensile reinforcement for beams.
   Clause No.26.5.1.2: Compression reinforcement.
   Clause No.26.5.1.3: Side face reinforcement.
   Clause No.26.5.1.5: Maximum Spacing of shear reinforcement.
   Clause No.26.5.1.6: Minimum shear reinforcement.
   Clause No.26.5.1.7: Distribution of torsion reinforcement.
   
4. Provisions for Columns :
   Clause No.25.1.2: Short and slender compression members.                                       Clause No.25.1.3: Unsupported length.
   Clause No.25.2 : Effective length of compression members.
   Clause No.25.3: Slenderness limits for columns.
   Clause No.25.4 : Minimum eccentricity.
   Clause No.26.5.3.1: Longitudinal reinforcement.
   Clause No.26.5.3.2: Transverse reinforcement.
   Clause No.43 : Cracking consideration.
   
5. Provisions for footings :
   Clause No.34.1.2 : Thickness at the edge of footing.                                                         Clause No.34.4 : Transfer of load at the base of columns.
   Other references / Literature generally referred to are
   1.Reinforced Concrete Designer’s Hand Book by Reynolds & Steelman. 2.Limit State Theory & Design of Reinforced Concrete by Karve and Shah. 3.Hand Book of Reinforced Concrete Design (I.S.455-1978) by Karve. 4. Limit State Design of Reinforced Concrete by Vergis.

• GENERAL PRACTICE FOLLOWED IN DESIGNS CIRCLE :
  (i) The loading to be considering for design of different parts of the structure including wind loads shall be generally as per I.S.:875-1987 (Part I to IV) and I.S.:1893-2002 (seismic loads) with their latest amendments/s.
  (ii) Live load for sanitary block shall be 200 kg/m2.
  (iii) Lift machine room slab shall be designed for live load of 1000 kg/m2.
  (iv) Lift loads shall be considered as per relevant I.S. codes as per capacity of lift and the same shall be increased by 100% for impact while designing.
  (v) Loading due to electrical installation e.g. A.C. ducting, exhaust fans etc. shall be got confirmed from the Executive Engineer, electrical wing of P.W. Department.
  (vi) Seismic loads shall be as per I.S.:1893-2002 and I.S.43261993. The method of analysis and values of various parameters shall be taken as per relevant provisions of the codes.
  (vii) Ductility provisions specified in I.S.:4326-1993 and I.S.:13920-reaffirmed 1998 Edition 1.2, 2002-2003 shall be adopted in design, for the buildings located in Seismic Zone III, IV & V.
  (viii) Any other loads which may be required to be considered in the designs due to special type or nature of the structure shall be got approved in advance from the Superintending Engineer.
  (ix) Deduction in dead loads for openings in walls need not be considered.
  (x) Unless otherwise specified, the weight of various materials shall be considered as given below :
  (a) Brick masonry :1920 kg/m3
  (b) Reinforced cement :2500 concrete kg/m3.
  (c) Floor finish for : 100 heavy weight suitably kg/m2 added and for light weight subtracted.
  (d) Brick Bat Coba of : 200 112 mm. thickness kg/m2 laid on terrace for water proofing treatment.
  (e) Brick Bat Coba in :1920 bath & W.C. kg/m3. depending on thickness of water proofing treatment .
  (xi) The analysis shall be carried out separately for dead loads, live loads, seismic loads, wind loads. All the structural components shall be designed for the worst combination of the above loads as per I.S.:1893-2002.
  (xii) Minimum reinforcement in all structural members shall be as per relevant clauses of I.S.: 4562000.
  (xiii) The R.C.C. detailing in general shall be as per SP:34 and as per the sketches given in this guidelines.                                                                                                                (xiv) High Yield Strength Deformed bars shall be used for main and distribution reinforcement.
  (xv) Diameter of bars in footings, shall be not less than 10 mm.
  (xvi) Spacing of stirrups in beams shall not exceed 25 cm.
  (xvii) Thickness of slab shall not be less than 12 cm. and in toilet blocks not less than 15 cm.
  (xviii) Depth of beam shall not be less than 23 cm.
  (xix) Spacing of ties in columns shall not exceed 25 cm.
  (xx) The longitudinal bars in columns shall not be less than 12 mm. in diameter.  

CHAPTER-III
GENERAL PROCEDURE OF DESIGN

• GUIDELINES FOR PREPARATION OF R.C.C. LAYOUTS.

1. The preparation of R.C.C. layouts involves fixing of locations of columns and beams, denoting slabs with respect to design live load, type of slab and numbering these structural elements.
2. There are two types of joints which need to be considered in the layouts. They are (a) movements joints, (b) Expansion joints.
3. If the length of building exceeds 45 m., expansion joints shall be provided to split it into suitable parts which are individually less than 45 m. in length. Building having wings in different directions shall be provided with expansion joints at the connection of the wings to central core to avoid torsional effects. Expansion joints may also be provided when there is a sudden change in plan dimensions. For details of the joints refer to I.S.:3414-1968, I.S.:4326-1976 and I.S.:3370-1965 (Part-I), I.S.:1893-2000.
4. In case the building is having different number of stories for different parts of the building, thus having different dynamic characteristics, then such parts shall be kept separated by a movement joint to avoid unequal loading, unequal settlement and collusion during an earthquake. Movement joints may also to be provided if the different parts of building are located on different stratas and of different safe bearing capacities. Such movement joints, however shall be provided right to the bottom of the foundation, unlike the expansion joints which are provided only upto the top of the foundation. In this regard refer to S.P.34, (explanatory Hand Book of I.S.:456-2000 clause 27 and also refer clause 5.1.1 of I.S.:43261993. As per this clause the minimum total gap between these joints shall be 25 mm.
5. Separate R.C.C. layouts are to be prepared for different levels i.e. plinth, typical or at each floor level (if the plans are not identical at all floor levels) terrace floor level, staircase block roof level and where applicable lift machine room floor level, lift machine room roof level, water tank bottom level.
6. R.C.C. layouts are generally prepared on tracing paper from the architectural drawings, by tracing only the walls, columns and other structural members. In the layout, the door and window positions are not shown.

• NUMBERING SYSTEM AND NOTATIONS TO BE ADOPTED IN LAYOUTS

1. Columns:
   Columns are numbered serially with integer number suffixed to letter “C” i.e. C1, C2, C3 etc. The columns are numbered from lower most left corner of the R.C.C. layout. Numbering shall proceed from left to right in X direction and proceeding successively in positive ‘Y’ direction. R.C.C. layout showing column numbering is kept as page 43.
2. Beams :
   (i) Beam actually supported over a column is called main beam. Beam supported over other beam is called secondary beam.
   (ii) A beam number is composed of two parts e.g.5.1, 5.2 etc. The part to the left of decimal point denotes the left side reference column number. The part to the right represents serial number of the beam.
   Beams in X direction here the reference column is left supporting column. If left supporting column is absent then right supporting column is considered as reference column. For X direction beam serial number (2nd part) is always odd e.g. 1, 01, 3, 03 etc. Beams to the right side of reference column is numbered as 5.1 etc. While beams to the left of reference column is numbered as 5.01, where the reference column is C 5.
   Beams in ‘Y’ direction in this case reference column is bottom most column. If the bottom column is absent then the upper supporting column can be considered as the reference column. For Y direction beam serial number (2nd part) is always even number e.g.5.2, 5.02, 5.4 etc. Beams in positive Y direction of reference column are numbered as 5.2 while beams in negative Y direction of the reference column are numbered as 5.02, where the reference column number is C 5.
3. For numbering the secondary beams in “X” direction the first part of beam number shall be a reference column which shall be the nearest left side column of the beam. The second part shall be odd number except ‘1’ i.e. 3, 5 etc. serially in X direction. e.g.5.3, 5.5 etc.
   Similarly secondary beams in Y direction can be numbered e.g. 5.4, 5.6 etc. except “2”.
4. If the beams are at intermediate level above the floor under consideration then the beam number will be suffixed with a letter like A, B & M. e.g. If 5.1 is main beam at 1st floor level, 5.1 A is a beam in X direction at 1st floor lintel level, and 5.2 M is a beam in Y direction at MID-LANDING LEVEL between the 1st floor and 2nd floor levels. “A” refers to floor level and “B’ refers to lintel level and “M” refers mid-landing level. 

• Slabs :
  The slab notation is composed of four parts. The first, second and third part are written on the left side of the decimal point and the 4th is written on the right hand side of the decimal point e.g. 200S1.1, 500S2.2.
  (i) The first part denotes the imposed live load intensity in Kg./sqm. for which the particular slab is designed. This load is decided on the basis of designated use of the particular space (the slab) as shown in the Architect’s plans and as per provisions of I.S.875. This practice is useful and advantageous for maintaining a proper record especially when different slab panels are designed for different live loads. This record is also useful to avoid over loading of the slab in future change of usage.
  (ii) The second part represents the type of the slab fore e.g.
  “S” denotes general floor slab, “SF” denotes staircase flight slab, “SR” denotes room roof level slab / staircase room roof level slab, “SM” denotes machine room floor slab “SC” denotes cantilever slab and “ST” denotes terrace slab.
  (iii) The third part is either “1” or “2” , “1” denotes the slab is one way. The “2” denotes the slab is two way.
  (iv) The fourth part is the serial number of the slab in one way/two way category. Slabs having different end conditions shall be treated as different slabs for this notation.
  (v) Slabs shall be grouped on the basis of panel dimensions, loading pattern and end conditions.
  (vi) The notation for one way slab, two way slab, 23 cm. brick wall, 15 cm. thick brick wall, R.C.C. pardi is shown on sample R.C.C. layout kept at page 43. The dead load of various structural material and live loads adopted for different slabs and the R.C.C. layouts shall be got approved from Superintending Engineer.
• GUIDELINE FOR FIXING THE POSITION AND ORIENTATION OF COLUMNS IN THE LAYOUT.
  This is an important stage. It is skillful job and economy in design is achieved by locating columns at proper and/ideal locations.
  (i) Normally the positions of the columns are shown by Architect in his plans.
  (ii) Columns should generally and preferably be located at or near corners and intersection/junction of walls.
  (iii) If the site restrictions make it obligatory to locate column footings within the property line the column may be shifted inside along a cross wall to accommodate footings within the property line. Alternatively trapezoidal footing, eccentric footing can also be adopted.
  In residential buildings, generally columns should be located at 3 to 4 m.c/c. to avoid large spans of beam. This will also control deflection and cracking.
  (iv) While fixing the orientation of columns care should be taken that it does not change architectural elevation. This can be achieved by keeping the column orientations and side restrictions as proposed in plans by the Architect.                       (v) As far as possible, column projection/s outside the walls should be avoided, unless Architect’s plans show contrary or same is required as structural requirement.
  (vi) Columns should not obstruct door and window position/s shown in the Architect’s plans.
  (vii) As far as possible columns should be so positioned, that continuous frames from one end to the other end of building in both X and Y directions are available. This will increase the global stiffness of the building against horizontal forces.
  (viii) When the locations of two columns are near to each other (for e.g. the corner of the building and intersection of the walls) then as far as possible only one column should be provided or secondary beam shall be provided.
  (ix) As far as possible columns should not be closer than 2m. c/c to avoid stripped/combined/continuous footings. Generally the maximum distance between two columns should not be more that 8m. c/c.
  (x) Column should be normally provided around staircases and lift wells.
  (xi) Preferably overhead water tank should rest on the columns as shown in the Architect’s plan. The height of water tank should be upto 2.0 m. Clear height between top of Terrace and Bottom of water tank should not be less than 0.90 m.
  (xii) Twin columns of equal size are desirable at expansion joints from aesthetic point of view.                                                                                                                                               (xiii) As far as possible every column must be connected (tied) in both directions with beams at each floor level, so as to avoid slender columns.
  (xiv) As far as possible columns supported on beam should be avoided. (Such columns are commonly called as floating columns)
  (xv) When columns along with connecting beams form a frame, the columns should be so orientated that as far as possible the larger dimension of the columns is perpendicular to the major axis of bending. By this arrangement column sections and there reinforcement are utilized to the best structural advantage.
• GUIDELINES FOR FINALISING THE BEAM POSITIONS :
  (i) Normally beams shall be provided below all the walls.
  (ii) Beams shall be provided for supporting staircase flights at floor levels and at mid landing levels.
  (iii) Beams should be positioned so to restrict the slab thickness, to 15 cm, satisfying the deflection criteria. To achieve this, secondary beams shall be provided where necessary.
  (iv) Generally we come across with the situation that there is a gap between the floor level beam and beam supporting the chajja. Here the depth of floor beam shall be so chosen that it can support chajja also. However if depth so required is large (distance between floor beam bottom and lintel top, greater than 30 cm) provide separate beam.                                                                                                                                                      (v) As far as possible, cantilever beams should not be projected from beams, to avoid torsion.
  (vi) Beams of equal depths shall be provided on both sides of the expansion joint from aesthetic point of view.
  (vii) To get the required minimum head room, following alternatives can be tried. (a) Reduce the beam depth without violating deflection criteria and maximum percentage of steel criteria for beams.
  (b) In case there is a wall, over the beam without any opening, inverted beam may be provided in consultation with Architect.
  (viii)Where secondary beams are proposed to reduce the slab thickness and to form a grid of beams, the secondary beams shall preferably be provided of lesser depth than the depth of supporting beams so that main reinforcement of secondary beams shall always pass above the reinforcement of main beams.
  (ix)In toilet block provide minimum number of secondary beams so that casting of slabs and beams will be simple. ‘No secondary beam’ condition would be ideal. (x) Beams which are required to give a planer look from the underside shall be provided as Inverted Beams, e.g. canopies.
• GUIDELINES FOR FIXING THE SLAB DIRECTIONS :
  (i) Slab shall be designed as one way slabs if ratio of Ly to Lx is more than 2 and two way slab, if the ratio is equal or less than 2. Where Lx is shorter span and Ly is longer span of the slab.
  (ii) However as per Designs Circles practice slabs upto 2.5 m. spans may be designed as one way slabs.
  (iii) Canopy, Chajja, balcony slabs are generally provided as cantilever slabs.
  (iv) W.C. slab is generally made sloping or sunk by about 50 cm. OR as indicated in architect’s drawing below general floor level for Indian type water closet. Slabs for toilet block and Nahani slab are generally sunk by 20 cm. OR as indicated in architecture’s drawing below general floor level.
  (v) Staircase waist slab shall be generally one way slab.
  (vi) Loft slabs over toilets are generally supported on partition walls of toilet and W.C. Loft load should be considered while designing the beams supporting these walls.
• PRELIMINARY BEAM DESIGN (P.B.D.) All secondary beams may be treated a simply supported beams.

1. Begin with fixing the dimensions of beam. The width of the beam under a wall is preferably kept equal to the width of that wall to avoid offsets i.e. if the wall is of 23 cm. then provide beam width of 23 cm.
2. Minimum width of main and secondary beam shall 23 cm. However secondary beams can be of 15 cm. in case of beams of toilet block. The width of the beam should also satisfy architectural considerations.
3. The span to depth ratio for beam be adopted as follows :
   For Buildings in seismic zone between 10 to 12 and for non-seismic zone 12 to 15.
   In case of Building located in Seismic Zone III, IV, V width to depth ratio shall be more than 0.30. The depth so calculated shall be as shown in the Architect’s plan.
4. To limit deflection, of a beam (up to 10 m. span) within the permissible limit, under service load, the I.S.:456 clause 23.2.1 provides the following span to depth ratios.
   (i) For cantilever not more than 7
   (ii) For simply supported beam not more than 20.
   (iii) For continuous beam not more than 26.
   These ratios can be further modified according to Modification Factor depending upon percentage steel used in the section as per I.S.:456 clause 23.2.1 (e).
5. The beams shall be designed as deep beam/slender beam as the case may be.
6. The beam shall be treated as
   (i) A rectangular beam if it does not support any slab on either side also if it is an inverted beam.
   (ii) As “L” beam if it supports a slab on one side and                                                            (iii) As “T” beam if it supports slab on both sides.
7. Arrangement of imposed load :
   (a) Consideration may be limited to combinations of :
   (i) Design dead load on all spans with full design live load on two adjacent spans.
   (ii) Design dead load on all spans with full design live load on alternate spans.
   (b) When design live load does not exceed 75% of the Design Dead load, the loading arrangement may be, Design Dead load and Design live load, on all spans.
8. For beams and slabs continuous over supports, Load combinations given in 5.7 above may be assumed.
9. STAAD and Struds software is used for design.

• PRELIMINARY COLUMN DESIGN AND DETERMINATION OF SIZE OF COLUMN SECTION : (P.C.D.)

1. The dimensions of a particular column section, is decided in the following way :
   (i) A column shall have minimum section 23 cm. x 23 cm. if it is not an obligatory size column.
   (ii) The size of the obligatory column/s shall be taken as shown on the architect’s plan. For non obligatory columns as far as possible the smaller dimension shall equal to wall thickness as to avoid any projection inside the room. The longer dimension should be chosen such that it is a multiple of 5 cm. and ratio Pu/fck bd is restricted to, for non-seismic area 0.4 (for corner columns it may be 0.35) and for seismic region 0.35 (for corner columns it may be 0.30).
   Where Pu, Fck, B, D have the following meaning :
   Pu is the factored load on the column. (in Newton)
   Fck is characteristic compressive strength of concrete. (Newton/mm2)
   b is the breadth of the column (mm).
   d is the depth of the column (mm)
2. The above ratios will ultimately help in keeping the requirements of steel for column within 0.8 to 2.5% which is economical and will avoid congestion of steel. Generally the concrete mix in R.C.C. work shall be as per Table No.5 of I.S.:456-2000. For moderate exposure condition M- 20 for R.C.C. and for severe exposure condition minimum grade shall be M-30.
3. If the size of a column is obligatory or if size can not be increased to desired size due to Architectural constraints and if the ratio of Pu/fck bd works out to be more than the limit specified above it will be necessary to upgrade the mix of concrete. For ease of construction frequent changes in column size should be avoided. As far as possible in multistoried building at least two floors should have the same column section. Preferably least number of column sizes should be adopted in the entire building and mix of all the columns on a particular floor should be same.
4. Effective length of column shall be calculated as per figure 26 and 27 of I.S.456-2000.
5. Columns shall be designed for direct load and uniaxial or biaxial bending considering different for load combinations as given in I.S.:456:2000.
6. Grouping of columns can be done on the basis of size, orientation and forces acting on it.
7. All R.C.C. layouts, tentative sizes of beam, and column sections should be got approved from the Architect before starting analysis of frames.

• ANALYSIS OF BUILDING FRAMES

1. In Designs Circle, at present, space analysis is done by treating the building as composed of only plane frames.
   A building may be required to be designed for Non Seismic/- Seismic Forces and/wind forces (whichever is governing) depending on the location, plan dimensions and height of the building.
2. An another software STRUDS is available in the Designs Circle. The same is used for small buildings.
3. The other inhouse programmes “FOOT”, “EC FOOT”, “SLAB”, “ASP2” are available. These Programmes are used for design of various components such as Isolated Footing, Combined Footing, Slab and Columns.
4. For buildings located in all Seismic Zone, seismic analysis is required to be carried out and ductile detailing is not done for Zone I & II. 
5. The magnitude of seismic nodal horizontal forces are worked out.
   Before starting the analysis of frames the forces for which the building is to be designed and the design parameters and particularly Importance Factor (I) and for Seismic Design to be adopted approved from Superintending Engineer.

CHAPTER-IV
STRUCTURAL MODEL AND SEISMIC ANALYSIS

• SEISMIC ANALYSIS

1. For Calculating seismic forces refer provisions of I.S.:1893-2002 (PART I)
2. It should be noted that provisions of I.S.:1893-2002 (Part I) are applicable to buildings, elevated structures, industrial and stack like structures, bridges, concrete masonry and earth dams, embankments and retaining walls and other structures.
   Temporary elements such as scaffolding, temporary excavations need not be designed for earthquake forces.
3. Dynamic analysis shall be performed to obtain the design seismic forces and its distribution to different levels along the height of the building, for the following buildings :
   a) Regular buildings : Buildings greater than 40 m. in height in Zone IV & V and those greater than 90 m. in height in Zone II and III.
   b) Irregular buildings : (As defined in Clause 7.1 of I.S.1893:2002 (Part I)
   All framed buildings for height more than 12 m. in Zones IV & V, and those greater than 40 m. in height in Zone II & III. Regular and irregular buildings other than above all seismic zones can be designed for seismic forces by static method of analysis.
   At present, most of the buildings we come across, use of static approach is adequate.
   However, for important buildings where it is felt necessary to carry out Dynamic Analysis, the Superintending Engineer may advice to carry out the Response Spectrum Method or Modal analysis.
   For all buildings checking for drift and torsion is necessary. This can be done by necessary commands in STAAD Pro Model Analysis.
   

• STATIC APPROACH FOR SEISMIC ANALYSIS
  

1. In this approach the structure is treated as a discrete system, having concentrated masses at the different floor levels which compose of mass that of columns and walls of half the floor above and half of the floor below.
   
2. Using details from STAAD Pro Model analysis the base shear can be worked out as follows :
   (i) Find seismic weight of the building; by taking sum of all reactions at footings level by considering full Dead load and Appropriate % of Imposed load as per Clause 7.3.1, Table 8 of I.S.:1893-2002 (Part I).

3. Seismic Analysis is carried out based on the following assumptions
(i) The Seismic Force acts, at a time along one direction only, i.e. when seismic force along with Dead and live load act on a space frame along X direction, then on Z direction only Dead and live load forces are acting and vise versa. Also, earthquake is not likely to occur simultaneously with wind or maximum flood or maximum sea weaves.
(ii) The nature of seismic force action is reversible in direction (i.e. + and – forces can act on the space frame)
(iii) Horizontal deflection of all joints of a frame, at particular floor level is same.
(iv) The individual space frame joint, shares the storey shear in proportion to its stiffness.
(v) The inverse of deflection of a joint is treated as a measure of its stiffness.
4. A judicious choice of beam sections (as explained in para 5) and column sections (as explained in para 6) will ensure deflection of the frames within permissible limits.
5. As per Clause 7.7.2, of I.S. 1893(Part-I):2002 to distribute horizontal lateral force to different lateral force resisting elements (joints), following procedure is done:
1) Find joint displacements of each joint by applying a unit horizontal fore say 5 KN or any Value in X & Z direction at each joint. (F element) and run the STAAD Pro Programme for load combination cases using partial load factor –1.
Generally the deflection in a frame at terrace level, is maximum.
As stated earlier the total base shear is shared in all X Z space frame joints of the building in inverse proportion of their deflections. The inverse of deflection for each space frame joint is calculated. Then using these values, ratio of (inverse of deflection of a particular frame joint (X/Z) Direction/sum of inverses of deflections of all (X/Z) Direction joint is worked out for each and every space frame joint. This value multiplied by the lateral force at that floor in a particular direction gives the Horizontal force to be applied at that joint in a particular direction.
6. After applying all horizontal seismic forces at all frame joints in X & Z direction, analysis is carried out for all required load combination cases and detailed space frame analysis results can be obtained.
All above calculations can be done by STAAD. Pro Programme output, using excel sheets.
For latest STAAD. Pro analysis programme, it is not necessary to calculate and apply seismic forces manually, but only by providing seismic parameters, STAAD Programme itself calculate and apply seismic forces both for static and dynamic analysis.
However, the designer should be alert to check the correctness of the seismic analysis done automatically by computer by verifying the result parameters like base shear, fundamental time period, Sa/g, seismic wt of building and deflections.

• WIND ANALYSIS:
  

1. As per I.S.875:1987 (Part-V) & I.S.1893:2002 (Part-I), it is always an assumption that earthquake is not likely to occur simultaneously with wind or maximum flood or maximum sea weaves.
   While designing, in the load combinations, dead load and imposed loads should be combined with either earthquake load or wind load.
   There are various types of structures or their components such as some tall buildings, chimneys, towers, long span bridges etc. which require investigation of wind induced oscillations.
   A large majority of structures met with in practice do not however, suffer wind induced oscillations, and do not require to be examined for dynamic effects of wind. These structures are to be analysed by static method.
   
2. Static method of wind load estimation which implied a steady wind speed, has proved to be satisfactory for normal, short and heavy structures.
   Analysis for wind forces by static approach is to be done as
   per Clause 5 & 6 of I.S.875:1987 (Part III)
   
3. Design wind speed is to be calculated …. Clause 5.3 of I.S.875:1987 (Part III) Vz = Vb K1 K2 K3
   Where,
   Vz = Design wind speed at any height Z in m/sec.
   Vb – Basic wind speed .. Fig.1 or Appendix ‘A’ of I.S.875:1987 (Part III) map of wind speed to be attached.
   K1– Probability factor .. C1 No.5.3.1 of I.S.875:1987 (Part III)
   K2– Terrain, Height & Structure size factor .. C1 No.5.3.2 of I.S.875:1987 (Part III)
   K3– Topography factor … Cl.No.5.3.3 of I.S.875:1987 (Part III).
   
4. After calculating design wind speed (Vz), design wind pressure is to be calculated as per Cl.No.5.4 of I.S.875:1987 (Part III).
   Pz = 0.6 Vz^2
   Where,
   Pz – design wind pressure in N/Sq.M. at height Z.
   Vz – design wind velocity in m/s at height z.
   
5. The wind load on a building shall be calculated for                                                                    a) Building as a whole .. C1 No.6.3 of I.S. : 875:1987 (Part III)
   F = Cf Ae Pd
   Where, F = Force acting in a direction specified in respective tables given in I.S.: 875 (Part-3)1987
   Cf – Force coefficient for the building .. Table 23 I.S.875:1987 (Part III)
   Ae – Effective frontal area of the building Pd – Design wind pressure
   b) Individual structure elements as roofs and walls or cladding units as per clause No.6.2.1 of I.S.875: 1987 (Part III).
   F = (Cpe – Cpi) A Pd
   Where,
   Cpe– External pressure coefficient
   Cpi – Internal pressure coefficient
   A – Surface area of structure element or cladding unit
   Pd – design wind pressure
   
6. After calculating the wind force, static wind analysis is done on following assumptions similar for earthquake analysis:
   (i) The wind force act at a time only along one direction i.e. when dead load, live load and wind forces are assumed to act on a frame along X direction then, along Z
   direction only Dead and live load forces are acting and vice versa.
   (ii) Horizontal deflection of all joints of frame at particular floor level, is same.
   (iii) The individual frames share the storey horizontal force in proportion to it’s stiffness.
   
7. Para 7.1 of the IS 875 (Part3):1987 stipulates that flexible slender structure and structural elements shall be investigated to ascertain the importance of wind induced oscillations or excitations along and across the direction of wind.
   In general the following guide lines may be used for examining the problem of wind induced oscillations.
   a) Building and closed structures with height to minimum lateral dimension ratio more than 5 and
   b) Buildings and closed structures whose natural frequency in the first mode is less than 1 Hz.
   Any structure or building which does not satisfy either of the above two criteria shall be examined for dynamic effects of wind. For the modal analysis (on similar lines of modal seismic analysis) will be carried out. If the wind induced oscillations are significant, analytical methods like use of wind tunnel modeling will have to be carried out.
   

• PREPARATION OF STAAD. PRO MODEL OF BUILDING.
  

1. After study of Architectural drawings and field data and with the help of R.C.C. layouts, STAAD. Pro Building Model can be prepared. The computer programme has two methods of input data for preparing STAAD Pro Model.
   a) Graphical Environment b) By analytical input of data.
   Designer may use either of the above methods or combination of both to prepare space frame building model. Following steps are followed :
   a) Analytical input of data :
   1) Write joint co-ordinates of each joint by command “Joint Coordinates” create nodes.
   2) These nodes are joined to each other to form a column, beam skeleton by command “Member incidences”.
   The space frame Geometry is so formed.
   3) Then column/beam sizes like width, depth are given by the computer programme command “Members property Indian”.
   4) Material Information is given by command “Define Material”. The information like E (Modulus of elasticity of concrete), Poisson ratio, density, Alpha value, Damping value for R.C.C. are given.
   5) “Constant” Command :
   This command is used for fixing column orientations by “Beta angle”.
   6) “Support” Command :
   Supports (Fixed/Pinned) are given by this command.
   7) “Member release” Command ;
   Simply supported ends of beams are released for moments by this command.
   8) “Members Offset” Command :
   By this command position of beam always from column center is fixed.
   By above Commands Building Geometry Model is prepared on STAAD Pro.
   
2. LOADING :
   STAAD. Pro Building Geometry so prepared is loaded by applying selfweight, wall loads, slab, lift loads, water tank loads etc. and Imposed loads, wind, seismic loads by creating different load cases. (Load 1, Load 2, Load 3 etc.)
   
3. Load combination cases are prepared by use of above primary load cases by command “Load Combination”.
   
4. Next command is “Perform analysis” and ”Load List”, last command is “FINISH”.
   

• ANALYSIS BY STAAD PRO
  

1. Programme : Checking of Input data:
   After preparation of STAAD Pro building Model, its input data shall be checked thoroughly by various commands available in STAAD Pro Software for its correctness.
   
2. RUNNING OF STAAD.Pro ANALYSIS PROGRAMME :
   By giving command “Perform Analysis” programme runs. And it gives results for the various Load Combination Cases provided to it.
   2.1 Programme STAAD.Pro to give results for various load combinations with the appropriate load factors as per I.S.:456-2000 and I.S.1893:2002 (when so specified in input data) namely :
   (1) 1.5 [Dead load + Live load]
   (2) 1.2 [Dead load + Live load + Seismic load] for Seismic analysis.
   (3) 1.5 [Dead load + Seismic load] for Seismic analysis.
   (4) 1.2 [dead load + Live load + Wind load] for wind analysis.
   (5) 1.5 [Dead load + Wind load] for wind analysis.
   (6) 0.9 Dead load + 1.5 Seismic/Wind load for stability of the structure.
   The designer has to decide which of these load combinations are required and accordingly give the details of horizontal loads.
   2.2 Programme output gives values of axial force, moment and deflections for each member and R.C.C. Design of beams (i.e. area of reinforcement, details of shear reinforcement, columns, slabs, footings, shear walls etc.)
   2.3 OUTPUT RESULTS FROM COMPUTER
   The results obtained by running Programme STAAD. Pro should be thoroughly checked before accepting the same in the final design.
   (A) The checking of input data is already discussed.
   (B) Checking of displacements
   (i) Displacement of joint are printed in meters. For fixed end of a frame the value of displacement must be zero.
   (ii) At hinged end of a frame horizontal and vertical displacement must be zero.
   (iii) The maximum horizontal displacement due to earthquake forces between successive floors shall not exceed 0.004 times the difference in levels between these floors.
   (iv) Displacement of all joints on a particular floor should be equal.
   (v) While checking of forces, at every joint following 3 equilibrium equations must be satisfied.
   (a) Sum of all vertical forces must be zero.
   (b) Sum of all horizontal forces must be zero.
   (a) Sum of all moments at the joint must be zero.
   Designer should personally check these points and check some joints for his own satisfaction.
   

• DESIGN OF VARIOUS R.C.C. ELEMENTS OF BUILDING
  After the analysis is over, the designer will undertake the detailed design of various members of the building in the following order of actual construction, to be in tune with construction programme decided by the Field Engineers.
  (i) Design of piles and pile caps/open footings (depending on the site and foundation conditions)
  (ii) Design of columns.
  (iii) Design of beams. (Plinth Level to Terrace Level)
  (iv) Design of slabs. (Plinth Level to Terrace Level)
  (v) Design of water tank/s.
  

1. DESIGN OF PILE AND PILE CAP
   Piles are required to be provided where the strata of adequate bearing capacity is not available at reasonable depth, and site conditions dictate that open foundation is not feasible and economical. This is generally the case in black cotton soils and reclaimed areas.
   For very low bearing capacity strata, and where pile foundation is not economical, we may adopt raft foundation. For codal provisions refer I.S.:2911.
   It is a good design practice to provide minimum two piles or 3 piles in triangular pattern and generally not more than 4 piles (in square pattern) be provided under a column.
   For piles, where the subsoil water is polluted and presence of sulfides and/chlorides is more than the safe limits, sacrificial cover shall have to be provided. However, the same shall be neglected while working out the area of concrete
   required to sustain the load on pile. The diameter of pile and pattern of pile cap for twin or triple pile group shall be so chosen that the adjoining pile caps do not get overlapped and there is at least minimum distance between the two adjacent pile caps as stipulated in the code I.S.2911.
   The mix of concrete considered for design shall be always one grade below than stipulated for casting.
   
2. DESIGN OF OPEN FOOTINGS
   2.1 ISOLATED FOOTINGS :
   (i) Write down the reactions at various footing points for different Load combination.
   (ii) The working load for each load combination is then worked out by dividing each load by the appropriate load factor of the particular load combination.
   (iii)The maximum value of all these working loads is taken as design working load on footing.
   (iv) The isolated footings are designed manually by using the design process as explained in HANDBOOK FOR R.C. MEMEBRS (Vol.II pages 359 to 380) OR any standard text book for R.C.C. Design.
   (v) Normally trapezoidal footing is provided except where the site conditions demand otherwise.
   (vi) Designer shall check that with the designed dimensions, the isolated footings are not getting overlapped. If they are getting overlapped, suitable combined footings shall be designed.
   2.2 COMBINED FOOTINGS :
   These are provided
   (1) At the expansion joint locations and
   (2) When it is noticed that the isolated footings, are getting overlapped or encroaching on adjoining property. The working load for combined footing shall be sum of working loads of columns constituting the combined footing. For manual analysis and design of combined footing, refer any standard textbook.
   
3. SPECIAL TYPES OF FOOTINGS :
   For design of pedestal or any other special type of footing like strip footing etc., refer standard text books.
   
4. DESIGN CHECKS FOR ALL TYPES OF FOOTINGS :
   The design shall be checked for following :
   (1) Check for single shear, double shear.
   (2) Check for negative moment (if active) (3) Check for bearing pressure on top of footing.
   
5. DESIGN OF COLUMN SECTION :
   5.1 A column is subjected to direct load and moments across its axes. Find out design loads and design
   moments across appropriate axes from the output of relevant X direction and Z direction frame analysis, for the design section under consideration in STAAD Pro software analysis.
   The column design by Limit State Method for reinforced concrete structures shall be as per following load combinations : (I.S.1893 Part I :2002, CL.6.3.1.2)
   1) 1.5 (DL + IL), 2) 1.2 (DL + IL + EL), 3) 1.5 (DL + EL), 4) 0.9 DL + 1.5 EL
   Similar combinations will be applicable in case of wind analysis i.e. replacing seismic forces by wind forces.
   The columns shall be designed as uniaxial or biaxial depending upon whether the moments are acting across one or both axes of column and their relative magnitudes.
   Effective length of column member shall be worked out considering end conditions and used in the calculations. (I.S.456:2000, Table 28, Cl.E-3)
   The design of column given by STAAD-Pro programme may be verified for its adequacy OR otherwise the column design is done manually as per “HANDBOOK FOR DESIGN R.C. MEMBERS” (Limit State Method) Vol.II as explained in pages to for uniaxial columns and for biaxial columns pages 322 to 337 and for circular columns pages 342. Computer programme “ASP2” is also available.
   The design section and the reinforcement shall satisfy all the combinations stated above.                                                                                                                                                     5.2 APPROACH FOR ECONOMIC DESIGN OF COLUMN :
   In the design of a column, two factors are to be keenly watched namely pu/fckbd and interaction factor.
   The pu/fckbd factor is a measure of compressive force in column and by keeping the value of this factor is equal to or less than 0.4, it is seen that the concrete section provided is utilised to the maximum extent.
   The interaction factor is a measure of degree of utilisation of steel reinforcement provided in the column section. The value of this factor (calculated as per clause 39.6 of I.S.456) as close to 1.00 ensures that the external loads and moments are resisted optimally by the proposed concrete section along with the (proposed) steel reinforcement pattern.
   5.3 Always begin by designing the top most section of a column and then proceeding successively to the lower section.
   5.4 Begin the design by choosing “one bar at each corner” i.e. 4 bar pattern (giving total area of reinforcement required on the basis of minimum steel criteria) and if this first approximation is not safe then modify the diameter of bars and/or reinforcement pattern till you get the interaction Ratio as close to 1.0.
   As far as possible for the next lower story column section, continue the same bar diameters and reinforcement pattern.
   5.5 CHOOSING PROPER REINFORCEMENT PATTERN
   While deciding the pattern it should born in mind that when the C.G. of the steel provided is away from the N.A., it gives higher moment of resistance to the section.
   5.6 If the first approximation of steel reinforcement proves inadequate, try to increase the diameter and/number of bars. It shall be ensured that in the pattern selected, the bigger diameter bars are always placed near the corner/faces away from axis of bending. Each successive trial shall be taken by gradually changing reinforcement, and the final trial should provide just adequate steel reinforcement. The reinforcement pattern should fulfill the minimum spacing criteria. The reinforcement bars are required to be laterally tied by providing links of proper shape.                                                                                                                                                     5.7 While choosing the reinforcement pattern, provide adequate number of bars so that it satisfies spacing criteria as per I.S.456, Cl.26.5.3.1 and Cl.26.5.3.2.
   5.8 A sketch giving the suitable link arrangements for column reinforcement which will create least congestion and aid easy flow of concrete in the steel cage is kept at page number 59 for guidance.
   5.9 The number of reinforcement bars shall be so chosen that for uniaxial column, equal area of steel on opposite faces is provided and for biaxial column, equal area area of steel on opposite faces is provided.
   5.10 For requirements of ductility detailing refer para 6.6 . (Page 35)
   
6.  DESIGN OF BEAMS :
   (i) The computer output of STAAD.Pro gives the area of required steel at supports, at quarter span (from each end) and at centre of span. The Designer has only to choose the diameter and numbers of top and bottom bars such that actual steel area is just more than the design value and there is no congestion of steel.
   Non congestion can be ensured by keeping horizontal distance between the bars as the greatest of the following :
   (a) The diameter of bar (in mm) if the diameters are Equal.
   (b) The maximum diameter (in mm) of bar if the diameters are Unequal.
   (c) 5 mm. more than the nominal maximum size of coarse aggregate.
   For ensuring better compaction of concrete with needle vibrator, it is desirable that this minimum clear distance be 50 mm.
   (ii) The anchor bars (at top and bottom) shall be minimum 2 Nos.
   (iii) Where it is not possible to accommodate all the bars in one layer, provide them in layers. The vertical distance between these layers shall not be less than the greatest of following :
   (a) 15 mm. (b) 2/3 of the nominal maximum size (in mm) of coarse aggregate.
   (c) Nominal size of bars (in mm.)
   (iv) As per Designs Circle’s practice bars at the bottom of beam are taken straight without bending.
   (v) When there are collinear beams over a support the extra steel over the support (at top and/bottom as the case may be) shall be maximum required for the either of the two.
   For collinear beams the extra steel over support shall be continued in the adjoining span for a length equal to anchorage length or 25 % of the adjoining span whichever is more.
   For non collinear beams the extra steel over support shall be anchored in supporting column for full anchorage length.
   (vi) The stirrups of shear reinforcement shall be provided with appropriate diameter of H.Y.S.D. bars so that there is no congestion of reinforcement in beam and it shall be seen that the ductility criteria where applicable is also fulfilled.
   6.1 For requirements of ductility detailing refer para 6.6 (page 35)
   
7. DESIGN OF SLABS :
   (i) The slabs may be one way or two way depending on the panel dimensions. The design moment coefficients of a particular slab shall be taken in accordance with its boundary conditions.
   (ii) Design of slabs is done manually by referring to “Handbook for R.C.C.” Members (Limit State Method) Vol. I or any standard textbook.                                                         (iii) As per Designs Circle’s practice minimum diameter of bars for slabs shall be 8 mm.
   (iv) In case of future vertical expansion, the R.C.C. layout of the top floor shall be as per Architect’s plan. However, the slab reinforcement shall be maximum of that required for future floor or present terrace.
   7.1 DESIGN OF OVERHEAD WATER TANK/S
   The design of water tank is carried out as per procedure given in the “Reinforced Concrete Designer’s Hand Book” by Reynolds, and conforming to I.S.:3370.
   

• COMPUTER AIDED DESIGN USING IN HOUSE DEVELOPED SOFTWARE
  With the availability of high speed and large memory capacity desk top computers in Designs Circle, much of the analysis is now carried out on these computers.
  Following is the list of computer programmes available in Designs Circle with User’s Manual :
  

1.  “FOOT” : This programme designs isolated footing as per limit state method of design. Column size, concrete mix, safe bearing capacity of the founding strata and working load on the column are the basic inputs. All the checks as per code are included in the programme.
   
2. “EC FOOT” : This Programme designs combined footing along the expansion joint. Column details alongwith their orientation expansion joint details etc. are basic inputs. All
   the checks as per code are included.
   
3. “SLAB” : This Programme designs one way and two way slabs as per “Limit State Method” design. The basic data is concrete mix, span/s, clear cover to reinforcement bars, slab loading and end conditions.
   
4. “ASP2” : The basic input required to run this programme are section dimensions, unsupported length and effective length in both X and Y direction, reinforcement pattern and different load combinations.
   The main limitation of this programme is that it is workable only with rectangular and square column section.
   This Programme designs for given column section, reinforcement pattern and, load combination and checks the adequacy of section. For this programme the X axis is always assumed to be along the smaller dimension of column. The programme output gives the results for the chosen column section and reinforcement pattern the values of [Pu/(fck x b x d)] and Interaction Factor Values for each load combination case under consideration.
   

• EARTHQUAKE RESISTANT DESIGN GUIDELINES AS PER I.S.:4326
  

1. The Seismic Design Philosophy is to accept damage to a building during a earthquake. Hence the I.S.:1893 code specifies design seismic force for a building, only a fraction of the seismic force that it will experience if it were to remain Linear elastic during severe ground motions. Thus the structure in severe seismic zones should be necessarily ductile.
   
2. Meaning there by that the members of reinforced concrete shall be under reinforced so as to cause a tension failure. Also it should be so designed that the premature failure due to shear or bond may not occur subject to the provisions of I.S.:456-1978. Ductile failure will enable structure to absorb energy during earthquake to avoid sudden collapse of structure.
   
3. I.S.:4326-1993 deals with earthquake resistant design and construction of design. Some important clauses are as under :
   Clause 4.4 Building Configuration
   4.4.0 In order to minimize torsion and stress concentration, provisions given in 4.4.1 to 4.4.3 should be complied with as relevant.
   4.4.1 The building should have a simple rectangular plan and be symmetrical both with respect to mass and rigidity so that the centers of mass and rigidity of the building coincide with each other in which case no separation sections other than expansion joints are necessary. For provision of expansion joints reference may be made to I.S.:3414-1968.
   4.4.2 If symmetry of the structure is not possible in plan, elevation or mass, provision shall be made for torsional and other effects due to earthquake forces in the structural design or the parts of different rigidities may be separated through crumple sections. The length of such building between separation
   sections shall not preferably exceed three times the width.
   4.4.3 Buildings having plans with shapes like, L, T, E and Y shall preferably be separated into rectangular parts by providing separation sections at appropriate places.
   Note 1.
   The buildings with small lengths of projections forming L, T, E or Y shapes need not be provided with separation section. In such cases the length of the projection may not exceed 15 to 20 percent of the total dimension of the building in the direction of the projection.
   Note 2.
   For buildings with minor asymmetry in plan and elevation, separation sections may be omitted.
   Clause 4.5 Strength in Various Directions
   The structure shall be designed to have adequate strength against earthquake effects along both the horizontal axes. The design shall also be safe considering the reversible nature of earthquake forces.
   Clause 4.6 Foundations
   The structure shall not be founded on such loose soils which will subside or liquefy during an earthquake, resulting in large differential settlements.
   Clause 4.7 Ductility
   The main structural elements and their connection shall be designed not to have a ductile failure. This will enable the structure to absorb energy during earthquakes to avoid sudden collapse of the structure. Providing reinforcing steel in masonry at critical sections, as provided in this standard will not only increase strength and stability but also ductility.
   Clause 5 Special Construction Features
   Clause 5.1 Separation of Adjoining Structures.
   Separation of adjoining structures or parts of the same structure is required for structures having different total heights or storey heights and different dynamic characteristics. This is to avoid collision during an earthquake. Minimum total gap shall be 25 mm.
   Clause 5.2 Separation or Crumple Section.
   5.21 In case of framed construction, members shall be duplicated on either side of the separation or crumple section. As an alternative, in certain cases, such duplication may not be provided, it the portions on either side can act as cantilevers to take the weight of the building and other relevant loads.
   

• DUCTILE DETAILING AS PER 13920:1993.
  I.S.:4326, The Code of Practice for earthquake resistant design and construction of Building, while commenting on certain special features for the design and construction of earthquake resistant buildings, included some details for achieving ductility in reinforced concrete buildings.
  The I.S.:13920 has taken note of latest developments, experiences gained from the performance of structures which were designed and detailed as per I.S.4326, during the recent earthquakes. It covers provisions for earthquake resistant design and detailing of reinforced concrete structures in particular. (As such it includes provisions of I.S.:4326 also). Now all ductility detailing shall comply I.S.:13920.
  Some important clauses of this code are as follows :
  Clause 1.1.1
  Provisions of this code shall be adopted in all monolithic reinforced concrete structures located in Seismic Zone III, IV & V.
  Clause 5.2 For all buildings which are more than 3 storeys in height the minimum grade of concrete shall be M 20.
  Clause 5.3
  Steel reinforcement of grade Fe 415 or less only shall be used.
  Clause 6 : For flexural members
  6.1.1 The factored axial stress on the member under earthquake loading shall not exceed 0.1 fck.
  6.1.2 The member shall have a width to depth ratio of more than 0.3.
  6.1.3 Width of flexural member not less than 200 mm.
  6.1.4 Depth of member not more than 0.25 of the clear span.
  Clause 6.2 : Longitudinal Reinforcement :                                                                                 6.2.1 (a) At least two bars at top and two bars at bottom shall be provided throughout the member length.
  (b) The tension steel ratio on any face at any section shall not be less than е (min) 0.24 [(square root of fck)/fy]
  6.2.2 The maximum steel ratio on any face at any section shall not exceed е (max)=0.025.
  6.2.3 The positive steel at a joint face must be at least equal to half the negative steel at that face.
  6.2.4 The steel provided at each of the top and bottom face of the member at any section along its length shall be at least equal to one fourth of the maximum negative moment steel provided at the face of either joint.
  6.2.5 In an external joint both the top and bottom bars of the beam shall be provided with anchorage length beyond the inner face of column equal to development length in tension plus 10 times the bar diameter minus the allowance for 90 degree bend(s).
  In an internal joint, both face bars of the beam shall be taken continuously through the column.
  6.2.6 The longitudinal bars shall be spliced, only if hoops are provided over the entire splice length at a spacing not exceeding 150 mm.
  The lap length shall not be less than the development length in tension.
  Lap splices shall not provided
  (a) within a joint
  (b) within a distance of 2d from joint face and
  (c) within a quarter length of member where flexural yielding may generally occur under the effect of earthquake forces.
  Not more than 50 percent of bars shall be spliced at one section.
  6.3.5 The spacing of hoops over a length of 2d at either end of a beam shall not exceed.
  (a) d/4 and (b) 8 x diameter of smallest bar
  But not less than 100 mm.
  The first hoop shall be at a distance not exceeding 50 mm. from the joint face. Vertical hoops at the same spacing as above shall also be provided over a length equal to 2d on either side of a section where flexural yielding may occur under the effect of seismic forces.
  Elsewhere the beam shall have vertical hoops at a spacing not exceeding d/2.
  Clause 7: Columns subjected to bending and axial load.
  7.1.1 These requirements apply to columns which have factored axial force in excess of (0.1 fck) under the effect of earthquake forces.
  7.1.2 The minimum dimension of column shall be 200 mm. However where in frames where beams have c/c span exceeding 5 m, or column having unsupported length exceeds 4 m. the shortest dimension shall not be less than 300 mm.                           7.1.3 The ratio of shortest dimension to the perpendicular dimension shall be preferably NOT less than 0.4.
  Clause 7.2 : Longitudinal Reinforcement
  7.2.1 Lap splices shall be provided only in the central half of the member length. It should be proportioned as a tension splice. Hoops hall be provided over the entire splice length at spacing not exceeding 150 mm. center to center.
  Not more than 50 percent of bars shall be spliced at one section.                                 7.2.2 Any area of a column that extends more than 100 mm. beyond the confined core due to Architectural requirements shall be detailed in the matter.
  In case the contribution of the area to strength has been considered then it will have the minimum longitudinal and transverse reinforcement as per this code.
  However if this area has been treated as non structural the minimum reinforcement shall be governed by I.S.456 provisions.
  Clause 7.3 : Transverse Reinforcement
  7.3.2 The spacing of rectangular hoops shall not be more than 300 mm c/c. If the length of any side of stirrup, exceeds 300 mm a cross tie shall be provided or a pair of
  overlapping hoops may be provided.
  Clause 7.4 : Special Confining Reinforcement
  7.4.1 This shall be provided over a length of (lo) from each joint face towards mid span on either side of any section lo shall not be less than
  (a) larger lateral dimension of the member
  (b) 1/6 of clear span of the member and
  (c) 450 mm.
  7.4.2 When a column terminates into a footing or mat special confining reinforcement shall extend at least 300 mm into the footing or mat.                         7.4.6 The spacing of hoops used as a special confining reinforcement shall not exceed 1/4 of minimum member dimension but need not be less than 75 mm nor more than 100 mm.
  7.4.7 The minimum area of cross section of bar forming circular hoop or spiral to be used as special confining reinforcement shall not be less than
  Ash = 0.09 S Dk (fck/fy) [(Ag /Ak -1.0 ] fy Where
  Ash = area of the bar cross section
  S = Pitch of spiral or spacing of hoops
  Dk = diameter of core measured to the outside of spiral or hoop
  fck = characteristic compressive strength of concrete cube.                                                 fy = yield stress of (spiral/hoop) steel Ag = gross area of column cross section Ak = area of concrete core should not exceed 300 mm (see figure 7)
  7.4.8 The area of cross section Ash of the bar forming rectangular hoop to be used as special confining reinforcement shall not be less than
  Ash = 0.18 Sh.fck [(Ag / Ak -1.0 ] fy Where
  h = longer dimension of rectangular hoop.
  Ak = Area of concrete core in the rectangular hoop measured to its outside dimensions.
  Clause 8 : Joints of frames :
  8.1 The special confining reinforcement as required at the end of column shall be provided through the joint as well, unless the joint is confined as specified by 8.2.
  8.2 A joint which has beams framing into all vertical faces of it and where each beam width is at least 3/4 of the column width, may be provided with half the special confining reinforcement required at the end of column. The spacing of hoops shall not exceed 150 mm.

CHAPTER-V
DETAILING

• NOTES TO APPEAR ON VARIOUS SCHEDULES
  [A] GENERAL (Applicable for all schedules) :
  1. For general instructions and detailing of reinforcement, refer to SP-34 of bureau of Indian Standards I.S.13920 and sketches in this chapter.
  2. Unless otherwise specified in the respective schedules, the minimum concrete mix shall be M 20 (characteristic strength 20 N/sq.mm.) and grade of concrete depending on exposure condition as per Clause No.8.2.2 and Table No.5 of I.S.456:2000.
  3. Reinforcement shall be high yield strength deformed bars (Fe 415) conforming to I.S.:1986 with latest amendments.
  4. Any deviations from designed sizes, found necessary on site shall be got approved well in advance before execution from Superintending Engineer.
  5. Development length of reinforcing bars shall be in accordance with Clause 26.2.1 of I.S.456:2000.
  6. Approval to R.C.C. layouts and to the sizes of columns and beams above plinth level shall be obtained from Architect prior to the execution.
  7. For notation of slabs, beams and columns and column orientation refer to R.C.C. layouts of respective floors.
  8. For all R.C.C. elements minimum cover shall be provided depending on condition of exposure described in 8.2.3 shall be as per Table 16 of I.S.456:2000 (Clause 26.4.2) and nominal cover to meet specified period of fire resistance shall be as per Table 16A of I.S.456: 2000, Clause No.26.4.3.
  [B] R.C.C. LAYOUTS :
  1. This R.C.C. layout is based on the Architect’s Drawing No…. Job No. , Dated. ….. .
  2. R.C.C. layout at a particular level indicates (i) beams and slabs at that level, (ii) supporting columns below that level and (iii) walls above that level.
  3. Any discrepancies noticed between these layouts and Architect’s drawings shall be communicated to office of ……. (where designs are prepared) for clarification before starting execution.
  4. Any change in the location of beams, orientation of column/s other than that shown in the layouts, shall be got approved in advance from Superintending Engineer.                                                                                                                                                   [C] FOOTINGS/PILES AND PILE CAPS :
  1. For column numbers and their orientation refer to R.C.C. layout at plinth level drawing No……./……. .
  2. The difference in levels between adjoining footings shall not exceed than that permitted vide Clause No.9.7 of I.S.:1904. 3. The larger dimension of a footing shall be oriented along the longer side of a column, unless the sketch indicates the contrary.
  4. Reinforcement parallel to breadth of footing shall be laid first.
  5. Reinforcing bars shall be bent up at the edges of footings to get required development length.
  6. The sub-soil and sub-soil water are assumed to be free from harmful elements.
  7. Footings/pile and pile caps are designed for (ground + –) (number of stories for which footings are designed).
  8. Footings are designed for safe bearing capacity of —- t/sq.m.
  9. For details of dowel bars and their arrangement refer to schedule of columns from footing to plinth level Drawing No…./… .
  [D] COLUMNS :
  1. For orientation of columns refer R.C.C. layout at plinth Drawing No….. /….. .
  2. Reduction in column size shall be effected from the top of the slab at relevant floor level.
  3. For any change proposed at site, in the size of column section and/or their orientation, approval of Superintending Engineer shall be obtained before execution.
  4. Larger diameter bars shall be provided at corners, unless otherwise indicated in the sketch.
  5. Arrangement of binders shown in the sketch is suggestive, any other alternative arrangement in accordance with the relevant provisions in I.S.:456 and I.S.:2502 may be adopted.
  [E] BEAMS :
  1. For notation of beams refer R.C.C. layout at …… floor level Drawing No……. / …… .
  2. In case of collinear beams, top reinforcement over a support for non-seismic region and both top and bottom reinforcement at a support for seismic region shall be continued in adjacent span for full development length or span/4 of adjoining span whichever is more.
  3. In case of collinear beam and in case there is no beam on the other side, the top reinforcement over a support for non-coastal region and both top and bottom reinforcement at a support for coastal region shall be anchored in the supporting column for full development length. In case of grid beams it shall be anchored in the supporting beams and columns.
  4. Minimum and maximum distance between individual bars shall be as per Clause No.26.3 of I.S.456:2000 with latest amendments.
  5. The end of a beam except in a grid not having either a column support or a collinear beam shall be considered to be a discontinuous end. The top and bottom reinforcement at such a discontinuous end shall be terminated in the supporting beams instead of anchoring for full development length.
  6. In case diameter and number of bars of adjacent collinear beams are same then these bars shall be kept continuous.
  7. If the spacing of stirrups in any region of a beam (such as 0 to D, D to 2d, etc. is not a submultiple of the depth of the beam, then the same spacing shall be continued in the next region for one more spacing before starting the new spacing to be provided in the next region.
  8. Extra steel at top of support between adjacent beams is shown in any one beam. This extra steel is to be continued on both sides of the support for required anchorage length or span/4 of respective beam, whichever is more.
  9. Top of internal plinth beams shall be 15 cms. below plinth level and top of external plinth beams shall be 15 cms. below ground level.
  10. Beams at toilet portion shall be cast 20 cm. below general floor level.
  11. Necessary provision for reinforcement of chajja, facias, canopy, fins, pardi and brackets etc. shall be made while casting of relevant beams.
  [F] SLABS :
  1. For notation of slabs refer R.C.C. layout at ……floor level Drawing No……. / ……. .
  2. Slabs of toilet portion shall be cast at 20 cm. below general floor level.
  3. Reinforcement in chajjas shall be provided as per the sketch No.4A of Designs Circle’s Technical Note No.7502.
  4. In slab notation, the first figure indicate the imposed live load assumed in design. It shall be ensured by the field engineers that the actual live load on the slab does not exceed this specified load.
  [G] WATER TANK :
  1. Mix of the concrete for water tank shall be M 20.
  2. All dimensions are in cms, unless otherwise specifically mentioned.
  3. Plans and sections are not to scale.
  4. Necessary water proofing treatment, load of which shall not exceed 100 kg/sq.m. shall be given to the tank.                                                                                                                     5. The drawing shows only structural details Air vents, over flow pipes, inlets, outlets, scour pipes, man holes etc. have not been shown on the drawing.
  6. Manholes of adequate diameter shall be provided as per requirement/s with extra trimmer bars below main reinforcement of slab as shown in the drawing.
  7. The horizontal and vertical bars of the walls shall be continued
  beyond the bend for full development length.
  8. The diameter and position of over flow pipe shall be such that it will ensure a free board of 15 cms.
  9. Column reinforcement shall be continued upto top of bottom slab of water tank.
  10. R.C.C. Tank/s of ….. Litres capacity shall rest on columns Nos…., …, …, …, …, and …
  
• VARIOUS FORMAT

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• FIELD DATA PROFORMA STANDARD PROFORMA FOR FURNISHING FIELD DATA FOR COMMENCING DESIGN OF BUILDING PROJECTS
  

•  SKETCHES 

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Shuttering Material Requirement

Auto Level

Setting up the instrument

The aim of this tutorial is to guide you through the procedures for setting up a tripod to make it ready for use.

Parts of the tripod

Basic Kit, tripod and instrument in carrying case

Each leg of a tripod is adjustable for length. The legs are locked by a lever clamp (left) or screw (right).

Once the legs have been set to the correct length it is important that the locking lever or screw is tight. Otherwise, the leg may move in use which means the instrument will have to be set up again, and all readings taken again as the instrument height will have changed.

Level in transit case. Note the plumb bob (lower left) which may be used to centre the instrument over a survey station.

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Setting up the tripod

Aim – to set up the tripod so that it is secure, the head is approximately level, the instrument telescope will be at eye level, you will be able to see the staff through the telescope

• Using a methodical approach keeps the task simple.
• Undo carrying straps

• Extend legs
• Set tripod in position – if the ground is sloping place two legs on the downhill side

• Firmly press the two tripod feet on the downhill side into the ground using your own foot on the tripod’s foot plate. (This will tilt the head)

Foot plate on tripod leg

• Move the third leg so that the head looks level and the instrument telescope will be at a comfortable height when this leg is firmly pushed into the ground.

• Fine adjustments can be made by changing the length of each leg.
  

• Make sure that the clamp or locking screw is tight when finished.

  Notes:

  If the tripod head is not almost level you may have difficulty setting up the instrument.

  Do not lean on the tripod when using it, as this could disturb the setting of the instrument.

• Tripod set up, legs secure, head level at a suitable height for use, ready for the instrument.

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Attaching the Instrument

The aim of this tutorial is to show you how to attach the level to the tripod. The attachment method is the same for most modern survey instruments including levels, theodolites, and EDM systems.

Attaching the instrument to the tripod

Tripod Head has a polished level surface for the instrument to stand on. Some tripods have a cover to protect the head when not being used. Take care not to damage the surface.

The Tripod Screw is captive and mounted on a movable bracket to allow the instrument to be centred over a station if necessary.

The instrument base plate (trivet stage) is threaded to take the tripod screw. The three raised ‘feet’ are machined to give a stable contact with the tripod head.

The tripod screw has a large head and is designed to be tightened and undone by hand. Do not apply undue force.

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Parts of the Instrument and Levelling Head

The aim of this tutorial is to introduce you to the automatic level and levelling head on the instrument. The three screw levelling head is found on most modern survey instruments including levels, theodolites, and EDM systems.

Typical parts of an automatic level

• The instrument is secured to the tripod head using the tripod screw.

Right side of Level

The levelling head has three parts:

• A top plate or tribrach which carries a spirit level and the instrument
• Three levelling, or foot, screws
• A foot plate or trivet that attaches to the tripod head

Also labeled in this picture:

• The horizontal circle, which allows the instrument to be used to measure horizontal angles to an accuracy of 1° (Not found on all instruments)
• The object focusing screw, which is used to bring the staff or other image in to focus.

Top of Level

This picture shows the instrument controls:

• Spherical level is a bubble spirit level attached to the tribrach and referenced to the axis of the telescope. In use the bubble must be within the circle for the instrument to give a horizontal sight line (Collimation).
• The eye piece is adjustable and should be set for each observer to bring the cross hairs in to sharp focus.
• The instrument can be rotated by hand, using the ‘gun sight’ on top of the telescope to find the staff.
• Tangent screws (one on each side) allow fine adjustment when aligning the telescope on the staff, or setting out a horizontal angle using the horizontal circle.
• The Telescope is focussed using the object focus screw on the right side of the instrument.

Left side of level

The only new component in this view is the mirror over the spherical level. This mirror allows the observer to see the bubble and confirm that the instrument is correctly levelled before taking a reading. Not all instruments will have a mirror.

Linear bubble level

Not all instruments have exactly the same features. This automatic level has a linear bubble level. It only has one tangent screw and the horizontal circle is replaced by marks at 90° intervals to allow setting out of right angles.

Eye piece focusing of the cross hairs and an object focus screw are usually provided on all instruments.

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Adjusting the levelling head

Aim – To level the tribrach so that the telescope rotates in a horizontal plane.

Levelling an instrument with a linear bubble tube.

• Align the bubble tube parallel to two foot screws.
• Facing the instrument rotate both foot screws in opposite directions at the same time. Either thumbs moving inwards or thumbs moving outwards.

• The bubble moves in the direction of the left thumb.
• When the bubble has settled in the exact centre of the tube the instrument is level on this axis.
• Rotate the telescope through 90° so the bubble tube is aligned with the third levelling screw.

• The first two screws are level so they must not be touched.
• Using the left hand adjust the third levelling screw to centre the bubble. Again the bubble will move in the same direction as the left thumb.

• With the bubble centred the instrument should be level.
• As a check rotate the instrument through 90°. If necessary re-level the original two foot screws and repeat the rotation to check the third one.
• You may have to do two sets of adjustments before the instrument is level and the bubble remains in the centre of the tube as the telescope is rotated.
• The tube is engraved with calibration marks to show the centre. The bubble must be no more than one space on the calibration scale off the centre for the compensator to work.

Levelling an instrument with a spherical spirit level.

• Align the telescope parallel to two foot screws.
• Facing the instrument rotate both foot screws in opposite directions at the same time. Either thumbs moving inwards or thumbs moving outwards.
• The bubble moves in the direction of the left thumb.

• When the bubble has settled opposite the centre mark the instrument is level on this axis.
• The bubble will probably be against the side of the circular spirit level, and needs moving in to the centre.

• The first two screws are level so they must not be touched.
• Using the left hand adjust the third leveling screw to centre the bubble. Again the bubble will move in the same direction as the left thumb.

• With the bubble centred the instrument should be level.
• As a check rotate the instrument through 90°. If necessary re-level the original two foot screws and repeat the rotation to check the third one.
• The tube is engraved with a calibration circle to show the centre. The bubble must remain within this circle for the compensator to work.

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Principle of the Automatic Level

The aim of this tutorial is to describe the basic principle of an automatic level.

Principle of levelling.

• The level is an optical instrument that provides a height reference. This reference is a horizontal plane through the axis of the telescope, known as the “Height of Collimation”.
• Once the height of collimation (or instrument height) has been measured the height of other stations can be found by measuring from this plane with a staff.
• The height of collimation is found by taking a backsight to a staff placed on a bench mark. The staff reading is added to the bench mark value to obtain the height of collimation.
• Once the height of collimation has been found ground height at any spot below this plane can be found by observing the staff and subtracting the staff reading from the height of collimation.

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Principle of the Automatic Level

The aim of this tutorial is to describe the basic principle of an automatic level.

The Automatic Level

• It is essential that the sight line through the telescope is exactly horizontal. If not errors will occur. One solution to this problem is the automatic level.
• The automatic level has a compensator mechanism that uses a combination of fixed prisms or mirrors and a moving prism suspended on a pendulum to give a horizontal reference. When correctly set up the compensator will ensure that the ray of light through the centre of the reticule is exactly horizontal.
• Design of the compensator mechanism varies with each manufacturer, so the diagram above is intended to show the principle of the method, not a specific instrument.
• Not shown in the diagram is a damping mechanism to stop the pendulum from continuing to swing when the instrument moves. The quality of the damping mechanism is very important; too little damping will give an unsteady image which may blur in windy conditions, but too much damping may lead to errors if the pendulum does not respond to slight movements of the instrument.
• The reticule is a glass plate with fine cross hairs engraved to provide the height reference. The eye piece should be adjusted to bring the reticule into sharp focus. The internal focussing lens is then controlled by the focussing screw on the side of the instrument to bring the staff image in to focus on the reticule.

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Staff and its graduation

Levelling staff.

• Two “E” pattern staffs are shown on the right, note slight differences in the marking and numbers. The “E” pattern is designed to make it easy to read a small section of the scale when seen through a telescope.
• The staff is simply a large ruler, available in lengths of 3, 4 or 5 metres and usually made of aluminium with telescopic sections.
• The sections have locking buttons to ensure accurate length is maintained.
• Some staffs also have an extended length scale in mm on the back.

•  Measurements are in metres and cm (10mm blocks) which enable heights to be estimated to 1 mm. Alternating colours are used to differentiate each metre length, the most common being black and red on a white background.
• Major graduations occur at 100 mm intervals and are denoted by figures. Minor graduations are at 10 mm intervals and form coloured squares or intervening spaces. The lower 50 mm of any 100 mm block are joined by a band to form the distinctive E pattern which is designed to make reading a small section of the staff in the telescope easier.
• Example staff readings are shown below:

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Through the telescope

Focus the reticule.

• The reticule (or diaphragm) is a glass plate with fine lines etched on it to provide the horizontal reference and stadia marks for estimating distance. When first looking through the telescope rotate the eye piece to bring the reticule in to sharp focus.
• Each observer will need to focus the reticule to allow for their own eye.
• Failure to do so will cause parallax, where a small movement of the eye’s position will cause the horizontal lines to give a different staff reading.
• With the eye piece focused you will see a vertical and a horizontal line dividing the field of view. The middle horizontal line marks the horizontal plane through the telescope (height of collimation) and is the reference for all height readings.
• There may also be two short stadia lines. Stadia are used for measuring the distance to the staff by multiplying the difference between the two stadia readings by a constant (usually 100).

Focus on the staff

• Align the telescope on the staff using the gun sight on the top of the instrument and gently rotating the telescope by hand.
• Using the side focussing screw bring the staff in to sharp focus.
• Fine adjustment of the alignment can be made with the tangent screw.
• Check that the spirit level bubble is within the central portion of the scale before reading the staff.

In this view the staff reading is 2.993

Upper stadia = 3.040
Lower stadia = 2.946
Stadia difference = 0.094
Distance to staff = 0.094 x 100 = 9.4 metres

Note that stadia distances have a low level of accuracy, one mm error in staff reading gives a distance error of 0.1 metre

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Through the telescope

Check that the staff is vertical.

• It is essential that readings are taken when the staff is vertical. If the staff is not vertical the reading will be larger than it should be, as you are measuring a slope distance, and will give errors.
• Some staffs are fitted with a spherical spirit level and handles to help the staff person keep it vertical. Even with a spirit level it is difficult to hold a staff vertical. This difficulty increases in wind.
• To read the staff when vertical the surveyor use the vertical reticule line to direct the staff person to move the top of the staff left or right of the sight line.
• The staff person then slowly tilts the top of the staff towards and away from the instrument so that it will pass through the vertical. The staff will appear to move up and down in the telescope field. The lowest reading is recorded as this is the point at which the staff is vertical.

 <- Staff leaning forward reading high

 <- Staff vertical lowest reading

 <- Staff leaning back reading high

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Height References

The aim of this tutorial is to introduce Bench Marks as a height reference.

OS Bench Mark (OSBM).

OS Bench Marks are established by the Ordnance Survey to provide height references. They are usually carved into stonework or other stable material that is unlikely to be disturbed.

The centre of the horizontal groove is the height reference.

Heights are given in metres above OS Datum on large scale OS plans and other references.

Temporary Bench Marks (TBM)

Temporary Bench Marks are often established around the survey site. TBMs may be surveyed in to the OS Datum by levelling between the site TBMs and an OSBM.

A site datum may be established instead and all levels referred to a TBM that has been given an arbitrary value (usually 100.000 metres, or a value that ensures all heights will be positive).

TBMs require to be stable. The main site reference is often a steel pin set in a block of concrete but wooden pegs set in concrete with a nail head providing the reference level are often used.

It is good practice to establish a number of TBMs around the perimeter of a building site as a precaution against the only site height reference being disturbed or dug up part way through the contract.

 

Stairs

Introduction

Reinforced concrete stairs are self-supporting or carried on beams or walls. They are often built around open or lift wells supported according to the type of structure. Staircase with cantilevering treads from a column or wall support are also commonly used for fire escape stairs, etc.

Note – Minimum steel, bar spacing and cover should conform to the requirements specified for slabs and of beams as appropriate.

Flight Supported on Side Beams

The reinforcement detail for a staircase supported by edge beams along each edge is similar to the one supported along its edges by a brick wall. Figure 10.1 shows cross-sectional details of a flight with two types of arrangements. 

10.2 Flight Supported on central beam – Figure 10.2 shows the cross-sectional details of a typical staircase supported on a central (stringer) beam. Each step of the the staircase is acting as a cantilever on both sides of the main beam. 

Flights and Landings Supported at Ends

Figures 10.3 and 10.4 illustrate two types of stairs with flight and landing supported at ends. Figure 10.3 gives reinforcement details of a flight spanning from outer edge to outer edge ot landing. Figure 10.4 gives reinforcement details of a flight together with its landings spanning from inner edge to inner edge of landings.

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Flight Supported on Brick Wall

Figure 10.5 shows the elevation detail for a straight stair flight with its landings at its ends supported by brick walls.

Cranked Beams

Straight stair flights and landings supported by side or centre beams as shown in Fig. 10.1 to 10.3 will require cranked beams. The elevation details of cranked beam is shown in Fig. 10.6.

The method of reinforcing a cranked beam is shown in Fig. 10.6. The bars at the intersections shall be carried for development length past the intersection, and one set of bars shall be cranked inside the other because of fouling. To complete the intersection extra bars, normal to the angle of intersection, are usually added as shown by the bars c and f.

Cantilever Stairs

A typical details of a tread cantilevering from a wall is given in Fig. 10.7. A typical detail of a staircase cantilevering from the side of a wall is shown in Fig. 10.8.

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Slabless Tread Riser Stairs

A typical detail of a slabless tread riser staircase is given in Fig. 10.9. 

Staircases are normally detailed diagrammatically in plan or section. This is best done by arranging the placing detail and bending schedule adjacent to one another on a single drawing sheet (see Fig. 10.10).

Re-entrant Corners

When tension bars meeting at a corner produce a resultant force resisted by the concrete cover, the bars shall be crossed over and anchored on either side of the cross-over by adequate anchorage length for taking up the stresses in the bar (see Fig. 10.11).

Hand Rail Supports

The designer should ensure that adequate consideration is given to the reinforcement detailing for handrail supports. If pockets are left in the concrete into which the hand rail posts are later concreted, the reinforcement shall pass around the pockets and be anchored into the main body of the concrete. If inserts are set into the concrete these should have steel bars passing around them to have sufficient anchorage ties build-in.

Where construction requires bars larger than 10 mm or 16 mm diameter should not be detailed to be rebend, but mild steel bars are recommended if re-bending is unavailable. 

Floor Slabs

Solid Slabs

Minimum Reinforcement

In solid reinforced concrete slabs, the reinforcement in either direction expressed as a percentage of the gross-sectional area of the concrete shall not be less than:

a) 0.15 percent where plain bars are used, and

b) 0.12 percent where high yield strength (hot rolled and cold twisted) deformed bars or welded wire fabric are used.

Spacing, Cover and Diameter

Spacing

a) The pitch of the bars for main tensile reinforcement in solid slab shall be not more than thrice the effective depth of such slab or 450 mm, whichever is smaller.

b) The pitch of the distribution bars or the pitch of the bars provided against shrinkage and temperature shall not be more than 5 times the effective depth of such slab or 450 mm, whichever is smaller. Table C-6 (see Appendix C) give area of bars for different spacing and diameter of bars.

Cover

a) The cover at each end of reinforcing bar shall be neither less than 25 mm nor less than twice the diameter of such bar.

b) The minimum cover to reinforcement (tension, compression, shear) shall be not less than 15 mm, nor less than the diameter of bar.

Bar Diameters

The main bars in the slab shall not be less than 8 mm (high yield strength bars) or 10 mm (plain bars) and distribution steel shall not be less than 6 mm diameter bars. The diameter of the bar shall not also be more than one-eighth of the slab thickness.

Simply Supported Slabs

Slabs Spanning in One Direction

A slab that is supported on two opposite sides only by either walls or beams is said to be spanning in one direction. The slab is considered as spanning in one direction even when the slab is supported on all four sides if the effective length of the slab exceeds two times its effective width. The shorter span is to be considered for design.

Figure 9.1 shows the general details of slab spanning in one direction. It clearly indicates the size and thickness of the slab and reinforcement, the cover and the spacing. Slab thickness shall be indicated both in plan and section. Where series of identical bars are used, it is customary to show only one bar. The bars in the shorter direction (main bars) are placed in the bottom layer. At least 50 percent of main reinforcement provided at mid span should extend to the supports. The remaining 50 percent should extend to within 0.1 x l of the support.

The bars in longer direction of the slab are called distribution or transverse steel. These assist in distribution of the stresses caused by the superimposed loading, temperature changes and shrinkage during the hardening process. These bars are placed in the upper layer and tied with the main steel bars to keep them in correct position during concreting.

Slabs Spanning in Two Directions

A simple slab spanning in two directions (ly/lx </= 2) and supported on four brick walls is shown in Fig. 9.2. As the slab is spanning in both directions the reinforcement in each direction shall be considered as main reinforcement. The bars in the shorter direction are generally placed in the bottom layer and tied with the bars iti the longer direction placed above at suitable intervals to keep their relative positions intact during concreting. At least 50 percent of the tension reinforcement provided at mid-span should extend to the supports. The remaining 50 percent should extend to within 0.1 x  lx, or 0.1 x ly, of the support, as appropriate, where lx, and ly, are effective spans in the shorter direction and longer direction, respectively.

Restrained Slabs

When the corners of a slab are prevented from lifting, the following simplified detailing rules may be applied, provided the slab is designed for predominantly uniformly distributed loads.

Note 1 – The analysis of uniformly distributed load and concentrated loads may be done separately, and with appropriate theories. The reinforcement quantities determined in this way should be superimposed.

Note 2 – If an end support is assumed to be a free support in the analysis, but if the character of the structure is such that restraint may nevertheless occur at the support, a restraint moment equal lo half the mid-span moment in the strip concerned may be adopted.

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The slabs are considered as divided in each direction into middle strips and edge strips as shown in Fig. 9.3, the middle strip being three-quarters of the width and each edge strip one- eighth of the width.

The tension reinforcement provided at mid-span in the middle strip shall extend in the lower part of the slab to within 0.25 x l of a continuous edge, or 0.15 x l of a discontinuous edge.

Over the continuous edges of a middle strip, the tension reinforcement shall extend in the upper part of the slab a distance of 0.15 x l from the support, and at least 50 percent shall extend a distance of 0.30 x l.

At a discontinuous edge, negative moments may arise. They depend on the fixity at the edge of the slab but, in general, tension reinforcement equal to 50 percent of that provided at mid-span extending 0.1 x l into the span will be sufficient.

Torsional Reinforcement

Torsional reinforcement shall be provided at any corner where the slab is simply supported on both edges meeting at that corner and is prevented from lifting unless the consequences of cracking are negligible.

It shall consist of top and bottom reinforcement, each with layer of bars placed parallel to the sides of the slab and extending from the edges a minimum distance of one-fifth of the shorter span. The area of reinforcement per unit width in each of these four layers shall be three-quarters of the area required for the maximum mid-span moment per unit width in the slab (see Fig. 9.4A).

Torsional reinforcement equal to half that described in 9.4.6 shall be provided at a corner contained by edges over only one of which the slab is continuous. (see Fig. 9.4B.)

Torsional reinforcement need not be provided at any corner contained by edges over both of which the slab is continuous.

A slab shall be treated as spanning one way (in the shorter direction) when ratio of effective span in the longer direction to the effective span in the shorter direction is greater than 2.

Figure 9.5 illustrates curtailment of bars in a restrained slab spanning in two directions based on the above rules using straight bars or bent-up bars.

Re-entrant Corners- Diagonal reinforcement shall be placed at all re-entrant corners to keep crack widths within limits (see Fig. 9.6).

Cantilever Slabs

The main reinforcement shall be placed in the top of cantilever slab extending to sufficient length over the support and back into the normal span. Tie method of curtailment shall conform to the requirements specified in Section 4.

Support to the top steel of cantilever slabs at spacings -(for stools and chairs) should preferably be specified in the detailing drawing. The bending of the main bars should be such that they contribute to the supporting of the steel, that is, bars that extend to the end should have vertical bends, with a fixing bar at the bend.

The secondary steel at right angles to the support may be designed and detailed to carry construction loading in the propped condition, if necessary.

The deflection in cantilever slabs can be reduced by the addition of compression steel at the bottom. This would also be helpful in counteracting possible reversal of bending moments.

The simplified curtailment rules illustrated in Fig. 9.7 may be used for cantilever slabs when they are designed for predominantly uniformly distributed loads.

Tie Backs and Counter Masses to Cantilevers

Cantilever at the bottom of beams

Ensure, when a cantilever is at the bottom of a beam, the design of the stirrups in the beam provides for moment, shear, hanging tension and, if necessary, torsion.

If possible, provide in the detailing of this steel for placing of the beam steel without the necessity of. the threading of the main beam steel through the cantilever anchorage loops. The details should conform to the basic principles applicable to opening corner in retaining walls and the beams. Figure 9.8 provides three alternative methods of anchoring bars in supporting beams.

NOTE- Note the special difficulty induced by bent-up bars in the beam steel:

a) Curtailed bars going to the back of a beam may drift out of position during casting of concrete.

b) Hairpin type bars should be related to the horizontal stirrup spacing, and this may cause difficulties.

c) Loops of 270° are difficult to bend and place in position.

Cantilever at the top of beams

Where the weathering course is 30 mm or less, crank the bars at a slope not exceeding 1 in 6 [see Fig. 9.9(A)]. Ensure that the combination of top bars and stirrups is such as to provide the required restraint. Note that if a bar is laced over and under the beam bars, it is fully restrained provided that the beam top bars are heavy enough and a stirrup is within 50 mm of such bar. If the bar is not so laced, detail the steel to ensure the anchorage against bursting (see Fig. 9.9).

 Cantilevers Around Corners

Ensure that, in a corner of a cantilever slab, the detailing is such that tie-back loading and the deflections that arise from this are accounted for. Avoid ‘fan’ type detailing. Take particular care with drainage inlets.

Openings in Slab

Special detailing for openings for lift shafts, large service ducts, etc, in the floors shall be given in the drawing. Such openings shall be strengthened by special beams or additional reinforcement around the openings. Due regard shall be paid to the possibility of diagonal cracks developing at the corners of the openings.

Note – The number, size and position of trimming bars is a function of the design, and should be determined by the designer.

Where openings are small and the slab is not subjected to any special type loading or vibration conditions, the following general detailing rules may be followed around openings (see Fig. 9.10 and 9.11):

a) At least one half the quantity of principal steel intersected by the opening is to be placed parallel to principal steel on each side of the opening extending Ld beyond the edges of the opening.

b) Diagonal stitching bars are put across the corners of rectangular holes or so placed as to frame circular openings. They should be placed both at top and bottom if the thickness slab exceeds 150 mm. The diameter of these bars should be the same as that of, the larger of the slab bars, and their length should be about 80 diameters.

Note – In general openings of diameter less than 250 mm or of size smaller than 200 x 200 mm may be treated as insignificant openings.

Slabs with Welded Wire Fabric

General

Welded wire fabric is either oblong mesh or square mesh arid is supplied in either rolls or flat sheets. The details regarding material, types and designation, dimensions, sizes of sheets or rolls, weight, tolerance, mechanical properties, etc, are all covered in IS : 1566-1982 ‘Specification for hard-drawn steel wire fabric for concrete reinforcement (second revision) ’ (see also Section 1).

Detailing

To ensure that correct size of fabric is laid in right direction, small sketches should be inserted on the plan to indicate the direction of span of the fabric. Details at A and B in Fig. 9.12 indicate square and oblong welded wire fabric, respectively, in plan view of slab.

The actual position of the welded wire fabric sheet in slab panels may be shown by a diagonal line together with the description of the mesh used. Bottom sheets should be shown with diagonal drawn from bottom left-hand corner to the top right-hand corner. Top sheets should be shown from top left-hand corner to the bottom right-hand corner. A schedule may also be included in the structural drawing indicating the mesh sizes, length and width, and cutting details for welded wire fabric sheets for different slabs panels. A typical plan is illustrated in Fig. 9.13 (see Section 5 for schedule).

Flat Slabs

General

The term flat slab means a reinforced concrete slab with or without drops, supported generally without beams, by columns with or without flared column heads (see Fig. 9.14). A flat slab may be solid slab or may have recesses formed on the soffit so that the soffit comprises a series of ribs (waffles) in two directions. The recesses may be formed by removable or permanent filler blocks.

(see Fig. 9.15)

a) Column strip -Column strip means a design strip having a width of 0.25 x l2, but not greater than 0.25 x l1 on each side of the column centre line, where l1 is the span in the direction moments are being determined, measured centre-to-centre of supports and l2 is the span transverse to l1, measured centre- to-centre of supports.

b) Middle strip – Middle strip means a design strip bounded on each of its opposite sides by the column strip.

c) Panel – Panel means that part of a slab bounded on each of its four sides by the Centre line of a column or centre line of adjacent spans.

Proportioning

The minimum thickness of slab shall be 125 mm.

Drops

The drops, when provided, shall be rectangular in plan and have a length in each direction not less than one-third of the panel length in that direction. For exterior panels, the width of drops at right angles to the non- continuous edge and measured from the centre line of the columns shall be equal to one-half the width of drop for interior panels.

Column heads

Where column heads are provided, that portion of a column head which lies within the largest right circular cone or pyramid that has a vertex angle of 90 degree and can be included entirely within the outlines of the column and the column head, shall be considered for design purposes (see 9.13).

 

Slab Reinforcement

Spacing

The spacing of bars in a flat slab shall not exceed twice the slab thickness, except where a slab is of cellular or ribbed construction.

Area of reinforcement

When drop panels are used, the thickness of drop panel for determination of area of reinforcement shall be the lesser of the following:

a) Thickness of drop, and

b) Thickness of slab plus one-quarter the distance between edge of drop and edge of capital.

Minimum length of reinforcement

a) Reinforcement in flat slabs shall have the minimum lengths specified in Fig. 9.16. Larger lengths of reinforcement shall be provided when required by analysis.

b) Where adjacent spans are unequal, the extension of negative reinforcement beyond each face of the common column shall be based on the longer span.

Anchoring reinforcement

a) All slab reinforcement perpendicular to a discontinuous edge shall have an anchorage (straight, bent or otherwise anchored) past the internal face of the spandrel beam, wall or column of an amount: 

1) For positive reinforcement – not less than 15 cm except that with fabric reinforcement having a fully welded transverse wire directly over the support, it shall be permissible to reduce this length to one-half of the width of the support or 5 cm, whichever is greater; 

2) for negative reinforcement – such that the design stress is developed at the internal face, in accordance with Section 4.

b) Where the slab is not supported by a spandrel beam or wall, or where the slab cantilevers beyond the support, the anchorage shall be obtained within the slab.

When the design is based on the direct design method specified in IS : 456-1978, simplified detailing rules as specified in Fig. 9.17 may be followed. A typical arrangement of bars in a flat slab with drop panels is shown in Fig. 9.17.

Openings in Flat Slabs

Openings of any size may be provided in the flat slab if it is shown by analysis that the requirements of strength and serviceability are met. However, for openings conforming to the following, no special analysis is required (see also 9.6):

a) Openings of any size may be placed within the middle half of the span in each direction, provided the total amount of reinforcement required for the pane1 without the opening is maintained.

b) In the area common to two column strips, not more than one-eighth of the width of strip in either span shall be interrupted by the openings. The equivalent of reinforcement interrupted shall be added on all sides of the openings.

c) In the area common to one column strip and one middle strip, not more than one-quarter of the reinforcement in either strip shall be interrupted by the openings. The equivalent of reinforcement interrupted shall be added on all sides of the openings.

Shear Reinforcement at Column Heads and Dropped Panels – The best method of providing shear reinforcement for slabs at column heads is to use beam cages in one direction and bars in the other direction laid under and on top of the steel in the cages (see Fig. 9.18).

Other methods such as the following may also be used depending upon their suitability:
a) Half or open stirrups suspended from the top steel;

b) Use of serpentine bars (see Fig. 9.19A).

c) Spiders made of bent bars (for deep slabs) (see Fig. 9.19B).

d) Structural steel frames made of plate. 

A few more methods of detailing shear reinforcement in flat slabs are given in Fig. 9.20 to 9.22.

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Waffle Slabs

Definition

A waffle flat slab is a two-way joist system. The two-way joist portion may be combined with a solid column head or with solid wide beam sections on the column centre lines for uniform depth construction.

Size of Waffles

Reusable forms of standard size shall be used for economy. These shall provide the width of rib at least 10 cm and spaced not more than 100 cm clear, and depth not more than 3.5 times the minimum width. Standard size may be adopted for these moulds as 50 x 50 cm, 60 x 60 cm, 80 x 80 cm, and 100 x 100 cm and depth as 15, 20, 25, 30, 35, 40, 45, and 50 cm

Detailing of Reinforcement in the Waffle Slab (With Solid Head and Square Interior Panel)

Ensure that at least 50 percent of the total main tension steel in the ribs is carried through at the bottom on to the support and anchored (see Fig. 9.23).

 

 

 

 

Customizing Views

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Resource Pooling and Consolidation

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Sharing Project Information

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Customizing Views

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Reporting and Troubleshooting

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Advanced Task Scheduling

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Tracking Project Progress

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Project Resources

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Project Tasks

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Creating a Project Plan

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Basics of Microsoft® Project 2013

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Overview of Microsoft® Project 2013

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Managing Projects Using MS Project 2013

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Other Agile Methodologies

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Introduction to Agile and Scrum

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Project Management Techniques—Overview

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Introduction to Project Management

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Beams

Arrangement of Bars

The main consideration when arranging bars in beam is to obtain the most economical layout to satisfy the design requirements. It shall also satisfy the relevant rules concerning horizontal and vertical spacing of bars and required bottom and side covers. While fixing the overall dimensions of beams, slenderness limits for beams to ensure lateral stability and span-to-depth ratios to control deflection, shall be kept in view.

The following .points shall also be noted in detailing (see Fig. 8.1).

a) The bars shall be symmetrically placed about the vertical centre line of the beams.

b) Where there are only two bars in a row, these shall be placed at the outer edges.

c) Where bars of different diameter are placed in a single bottom row, the larger diameter bars are placed on the outer side. 

d) Where bars in different horizontal rows have different diameter, the larger diameter bars shall be placed in the bottom row. 

Longitudinal Reinforcement 

Minimum Distance Between Individual Bars

The following rule shall apply:

a) the horizontal distance between two parallel bars shall be usually not less than the following:

1) diameter of the bar, if the diameters are equal;

2) diameter of the larger bar, if the diameters are unequal; and

3) 5 mm more than the nominal maximum size of coarse aggregate.

Note- This does not preclude the use of larger size aggregates beyond the congested reinforcement in the same mmkr, the size of aggregate may be reduced around congested reinforcement to comply with this provision. 

b) Greater horizontal distance than the minimum specified in (a) should be provided, wherever possible. However, when needle vibrators are employed, the horizontal distance between bars of a group may be reduced to two-thirds of the nominal maximum size of aggregate, provided vibrator can be used without difficulty.

c) Where there are two or more rows of bars, the bars shall be vertically in line and the minimum vertical distance between bars shall be 15 mm or two-thirds the nominal maximum size of aggregate or the maximum size of the bar, whichever is the greatest.

The minimum spacing requirements of reinfor-reinforcing bars in beams is illustrated in Fig. 8.1 and Fig. 8.2. 

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Tension Reinforcement

Minimum reinforcement – The minimum area of tension reinforcement shall not be less than that given by the following: 

Maximum reinforcement

The maximum area of tension reinforcement shall not exceed 0.04 bD, where b is the width of the beam rib or web and D is the total depth of the beam.

Maximum distance between bars in tension – Unless the calculation of crack widths shows that a greater spacing of bars in acceptable, the following requirements should be fulfilled for control of flexural cracking:

The horizontal distance between parallel reinforcement bars, or groups near tension face of a beam shall not be greater than the value given in Table 8.1 depending on the amount of redistribution carried out in analysis and the characteristic strength of the reinforcement (See Fig. 8.3)

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Compression Reinforcement

The maximum area of compression reinforcement shall not exceed 0.04 bD. Compression reinforcement shall be enclosed by stirrups for effective restraint. The anchorage length of straight bars in compression shall be equal to the development length of bars in compression.

Side Face Reinforcement

Where the depth of the web in a beam exceeds 750 mm side face reinforcement shall be provided along the two faces. The total area of such reinforcement shall be not less than 0.1 percent of the web area and shall be distributed equally on two faces at a spacing not exceeding 300 mm or web thickness, whichever is less (see Fig. 8.4). 

Detailing of Shear Reinforcement 

a) A stirrup in the reinforced concrete beam shall pass around or be otherwise adequately secured to the outermost tension and compression reinforcement, and such stirrups should have both its ends anchored properly in any one of the fashion detailed in Fig. 8.5. In T-beams and l-beams, such reinforcement shall pass around longitudinal bars located close to the outer face of the flange. While adopting stirrups, different shapes (see Fig. 8.6) may be considered depending on constructional requirements keeping in view the end anchorage requirements. However, while choosing a particular shape for a particular situation, its validity should be considered from structural point of view. 

b) Bent-up Bars

Tensile reinforcement which is inclined and carried through the depth of beam can also be considered to act as shear reinforcement provided it is anchored in accordance with 4.3.5 (see Fig. 8.7). Usually two bars are bent up at a time at an angle 45 degree to 60 degree to the longitudinal axis of the beam but other angles can also be adopted.
It is usual practice to combine bent up bars and vertical stirrups to resist the shear since some of the longitudinal bars are bent up when they are no longer required at the bottom (see Fig. 8.7). 

c) Maximum Spacing

The maximum spacing of shear reinforcement measured along the axis of the member shall not exceed 0.75 d for vertical stirrups and d for inclined stirrups at 45 degree, where d is the effective depth of the section under consideration. In no case shall it exceed 450 mm. 

d) Use of Multi-legged Stirrups

Multi-legged stirrups are required from the consideration of shear stresses in the beam, or where restraint against the buckling of bars in compression is needed. The rules for stirrups reinforcing steel in compression are the same as those for columns. The vertical stirrups may he provided as two-legged stirrups, four- legged stirrups or six-legged stirrups at the same section according to actual requirements (see Fig. 8.8). Open type stirrups as shown in Fig. 8.9 may be used for beam-slab construction where the width of rib is more than 450 mm. 

e)  Stirrups in Edge Beams

Where designer shows stirrups in any edge or spandrel beam, these stirrups shall be closed and at least one longitudinal bar shall be located in each corner of the beam section, the size of this bar is to be at least equal to the diameter of the stirrup but not less than 12 mm. These details P sha 1 be clearly indicated by the designer. Typical cross-sectional details are shown in Fig. 8.10 for normal and upturned edge or spandrel beams. For easier placing of the longitudinal bars in the beam, details for two-piece closed stirrups are also shown. For the same reason, 90 degree stirrup hook is preferred.

f) Minimum Reinforcement

The minimum shear reinforcement in the form of stirrups shall not be less than the following (see Fig. 8.11).

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However, in members of minor structural importance such a,s lintels, or where the maximum shear stress calculated is less than the permissible value, this provision need not be complied with. 

g) Beam of Varying Depth

Detail stirrup sizes individually where beams have varying depth. A range of stirrup sizes has to be detailed (see fig. 8.12 and also 6.10). 

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h) Force not Applied to Top of Beam

Where a load transfer is through the bottom or side of a beam (for example, where one beam frames into another), ensure that there is sufficient suspension or hang-up reinforcement at the junction in the main beam in the form of stirrups to transfer the force to the top of the beam. If the load is large, bent-up bars may also be used in addition to stirrups (see Fig. 8.13).

Torsion Reinforcement 

When a member is designed for torsion, reinforcement for the same shall be provided as follows (see Fig. 8.14A)

a) The transverse reinforcement for torsion shall be rectangular closed stirrups placed perpendicular to the axis of the member. The spacing of the stirrups shall not exceed the least of x1, (x1 + y1)/4 and 300 mm, where x1, and y1 are respectively the short and long dimensions of the stirrup. In a beam with multi-legged stirrup, only the stirrup going around the outer face shall be considered to resist torsional force. In members having a complex cross-section (such as I and T-sections), each part (flanges, ribs, webs, etc.) should contain closed stirrups of its own (see Fig. 8.14B and C). 

b) Longitudinal reinforcement shall be placed as close as is practicable to the corners of the cross-section and in all cases there shall be at least one longitudinal bar in each corner of the ties.

c) When the cross-sectional dimensions of the members exceeds 450 mm, additional longitudinal reinforcements shall be provided at the side faces and the total area of such reinforcement shall be not less than 0.1 percent of the web area and shall be distributed equally on two faces at a spacing not exceeding 300 mm or web thickness whichever is lower. 

Curtailment of Reinforcement 

The extent of curtailment of main reinforcement in beams should be related to the.bending moment diagram subject to the conditions specified in Section 4. However, simplified curtailment rules illustrated in Fig. 8.15, 8.16 and 8.17 may be used for continuous beams, simply supported beams and cantilever beams, respectively under the following circumstances:

a) the beams are designed for predominantly uniformly distributed loads; and

b) in the case of continuous beams, the spans are approximately equal (which do not differ by more than I5 percent of the longest).

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Edge and Spandrel Beam 

T-beams or L- beams are usually designed as internal and external beams supporting a floor slab; where part of the slab form the horizontal portions of the T- or I.-beam.
Where the reinforcement of a slab which is considered as the flange of T- or L.-beam, is parallel to the beam, transverse reinforcement extending to the lengths indicated in Fig. 8.18 shall be provided. If the quantity of such transverse reinforcement is not specially determined by calculations it shall not be less than 60 percent of main reinforcement in the centre of the span of slab constituting the flange.

Corners and Cranked Beams 

Recommendations for various methods of reinforcing corners are giving herein based on reference 6. It is to be noted that closing corners present no major problem, but opening corners require careful detailing (see Fig. 8.l9 and Fig. 8.20).

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90 degree Opening Corners With 1 Percent Reinforcement or Less

Where the amount of reinforcement in the beam is equal to or less than 1 percent, detail the reinforcement as shown in Fig. 8.21 or Fig. 8.22, the splay steel being equal to 50 percent of the main steel.

90 degree Opening Corners With More Than 1 Percent Reinforcement

If the area of reinforcement exceeds one percent. provide transverse steel as well as splay steel as in Fig. 8.23. (The use of a splay is also strongly recommended.) 

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Cranked Beams

The recommended methods of detailing are shown in Fig. 8.24, 8.25 and 8.26. 

Beam and Column Junction

Where a column extends above a beam, bend the beam top reinforcement down into the column but if it is necessary to bend the bars up, detail additional steel as in Fig. 8.27. 

 

Closing Corners

At closing corners provide adequate radii (equal to at least 7.5 bar diameters) and some additional reinforcement as in Fig. 8.28.

Beam of Different Depths

Typical arrangements of reinforcement over the support when the beam on either side of the support are of different depths is shown in Fig. 8.29

Tie Members

As a tie is under pure tension there is no tendency to burst like an axially loaded column and therefore binders are not required. But, in order to form the longitudinal bars into a cage, a minimum number of links is used. As there is theoretically no shear or bending moment acting on a tie, only main longitudinal reinforcement is required.

End Details

These shall provide adequate anchors and correct bond lengths. In consideration is the end conditions where a method should be devised to anchor the tie and/or spread its axial load into the connecting members. practice a small splay at the ends of the tie is made to allow for any slight moment that may be induced at the ends. Simple end details for light loading are shown in Fig. 8.30. The ties are shown by the arrows. 

 

For heavier axial loading, the ends shall be more splayed out to distribute * the load adequately. Typical details are shown in Fig. 8.3 I. In Fig. 8.31 (A and B) it will be seen that as the splay is increased in size, the embedded and hence bond length of the main tie bars is also increased. 

In Fig. 8.31 C extra links or hoops shall be provided as shown to resist the tendency of the large loop to burst under axial load. In Fig. 8.31 the main bars have been shown with double lines for clarity. When detailing they would be shown thick lines in t.he norma! way. 

Haunched Beam

In very heavily loaded beams, for example a warehouse structure, the shear stress and negative bending moment at the supports will be high. An economical method of overcoming this problems is to provide the beams with haunches as shown in Fig. 8.32. There are-no rules governing the size of haunches, but those shown in Fig. 8.32 are considered ideal.

Main Reinforcement in haunches

Figure 8.33 shows the typical main tensile reinforcement in an end external haunch. The main bars are carried through the haunch as if it did not exist, with pairs of bars a, b, c, etc, stopped off in accordance with a cut-off bending moment diagram. Bars h are placed parallel to the haunch to carry vertical links (omitted in the figure for clarity). A similar method of reinforcing to that shown in Fig. 8.33 can also be used for internal haunches. This is shown in Fig. 8.34. 

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Stirrups in Haunches

The stirrups in haunches can either be positioned normally to the haunch as shown in Fig. 8.35A, or placed vertically as in Fig. 8.358. Most designers prefer method shown in Fig. 8.35B.

If in Fig. 8.33 and 8.34, the h bars were placed near the outside edge of the beam they would foul the outside main horizontal bars. They should, therefore, be placed on the inside as shown in Fig. 8.36 so that two different sets of stirrups are required throughout the whole length of the haunch (see 8.10). 

Beam of Varying Depth

Stirrups need to be detailed individually wherever beams have varying depths and a range of stirrup sizes have to be adopted.  

The different stirrup sizes may be reduced in number by using concertina stirrups (see Fig. 8.12) with the legs lapped with tension lap length. The difference between the lengths of successive groups should be at least 50 mm. In order to maintain the correct size of the member, use closed stirrups at centre-to-centre distances of at least 1000 mm. Ensure that concertina stirrups are properly tied and maintained in position during concreting.

Intersection of Beams 

General

Ensure that, at beam-beam intersections, reinforcement is so arranged that layers in mutually perpendicular beams are at different levels.

Top Steel

It is good practice, for the following reasons, to pass the secondary beam steel over the main beam steel:

a) secondary beam steel is usually of smaller diameter and requires less cover, and

b) secondary beam top reinforcement is available to act as a support for the slab top reinforcement. Where the main beam is very heavily stressed, however, it may be more economical to pass the main beam steel over the secondary reinforcement.

Bottom Steel

To accommodate bottom bars, it is good practice to make secondary beams shallower than main beams, even if by only 50 mm (see Fig. 8.37). Where beam soffits are at the same level, the secondary beam steel should pass over the main beam steel. Unless the secondary beam span is short, bars of diameter less than 25 mm be draped (see Fig. 8.38). Cranking of bottom bars is usually not necessary. If it is required that the beam cages be pre- assembled. provide splice bars 7.6).

Openings in the Web

Adjacent openings for services in the web of flexural members shall be arranged so that no potential failure planes, passing through several openings, can develop. In considering this, the possible reversal of shear force, associated with the development of the flexural overstrength of the members, should be taken into account. 

Small square or circular openings may be placed in the mid-depth of the web provided that cover requirements to longitudinal and transverse reinforcement are satisfied, and the clear distance between such openings, measured along the member, is not less than 150 mm. The area of small openings shall not exceed  1000 sq.mm for members with an effective depth,d, less than or equal to 500 mm, or 0.004 d x d when the effective depth is more than 500 mm.

Note – Small openings with areas not exceeding those specified in 8.13.1.are considered not to interfere with the development of the strength of the member. However, such openings must not encroach into the flexural compression zone of the member. Therefore, the edge of a small opening would be no closer than 0.33 d, to the compression face of the member, as required by 8.12.3. When two or more small openings are placed transversely in the web, the distance between the outermost edges of the small openings should be considered as being equivalent to the height of one large opening and the member should be designed accordingly. 8.133 Webs with openings larger than that permitted by 18.12.1 shall be subject to rational design to ensure that the forces and moments are adequately transferred in the vicinity of the openings. This will require the design of orthogonal or diagonal reinforcement around such openings. 8.13.3, Whenever the largest dimension of an opening exceed one-quarter of the effective depth of the member, it is to be considered large. Such openings shall not be placed in the web where they could affect the flexural or shear capacity of the member, nor where the total shear stress exceed 0.36 sqrt. fck, or in potential plastic hinge zones. In no case shall the height of the opening exceed 0.4 d nor shall its edge be closer than 0.33 d to the compression face of the member to ensure that the moments and shear forces can be effectively transmitted by the compression zone of the member.

For openings defined by 8.13.3, longitudinal and transverse reinforcement shall be placed in the compression side of the web to resist one and one-half times the shear across the opening. Shear transfer in the tension side of the web shall be neglected.

Note – Only the part of the web above or below an opening which is in compression should be considered to transmit shear. The stiffness of the tension part is considered to be negligible because of extensive cracking. The amount, location and anchorage of the longitudinal reinforcement in the compression part of the web above the opening must be determined from first principles so as to resist one and one-half times the moment induced by the shear force across the opening. Similarly shear reinforcement in the compression chord adjacent to the opening must resist 150 percent of the design shear force. This is to ensure that no failure occurs as a result of the local weakening of the member due to the opening. Effective diagonal reinforcement above or below the opening, resisting one and one-half times the shear and moment, is also acceptable.

Transverse web reinforcement, extending over the full depth of the web, shall be placed adjacent to both sides of a large opening over a distance not exceeding one-half of the effective depth of the member to resist twice the entire design shear across the opening.

Note- At either side of an opening where the moments and shear forces are introduced to the full section of a beam, horizontal splitting or diagonal tension cracks are to be expected. To control these cracks, transverse reinforcement resisting at least twice the design shear force, must be provided on both sides of the opening. Such stirrups can be distributed over a length not exceeding 0.5 d at either side immediately adjacent to the opening.

A typical detail of reinforcement around a large opening in the web of a beam, complying with the above requirements, are Shown in Fig. 8.39.

 

Columns

General

Reinforced concrete columns are used to transfer the load of the structure to its foundations. These are reinforced by means of main longitudinal bars to resist compression and/or bending; and transverse steel (ties) to resist bursting force.

The column or strut is a vertical compression member, the effective length of which exceeds three times its least lateral dimension.

Longitudinal Reinforcement

• In a reinforced column, the area of longitudinal reinforcement shall not be less than 0.8 percent nor more than 6 percent of the gross cross-sectional area of the column. The area of longitudinal reinforcement should normally not exceed 4 percent of the gross cross- sectional area of the column. This percentage can. be considered as the maximum from practical considerations. However where bars from one column have to be lapped with those of another column above, the total maximum percentage of 6 percent may be allowed at the lapping. Proper placing and compacting of concrete should be ensured at the place of lapping.
• A minimum number of 4 bars shall .be provided in a column and six bars in a circular column with helical reinforcement.
• The bars shall be not less than 12 mm in diameter and spacing of the bars along the periphery of the column shall not exceed 300 mm.
• In the case of pedestals in which the longitudinal reinforcement is not taken -into account in strength calculations, nominal longitudinal reinforcement of not less than 0.15 percent of the gross cross-sectional area shall be provided.

Note – Pedestal is a compression member, the effective length of which does not exceed 3 times the least lateral dimension.

• Dowels and Bar supports

Dowels and bar supports, spacer bars, bar chairs, etc, should be specifically listed on the structural drawing and should be scheduled in that portion of the structure in which they are first required so that they can,be delivered with reinforcement and are available for placement in time. Footing dowels shall be scheduled with footings rather than in column. schedules.

Transverse Reinforcement

A reinforcement concrete compression member shall have transverse or helical reinforcement so disposed that every longitudinal bar nearest to the compression face has effective lateral support against buckling. The effective lateral support is given by transverse reinforcement either in the form of circular rings capable of taking up circumferential tension or by polygonal links (lateral ties) with internal angIe not exceeding 135 degrees. 

Arrangement of Transverse Reinforcement – Where the longitudinal bars are ‘pot spaced more than 75 mm on either side, transverse reinforcement need only to go round comer and alternate bars for the purpose of providing effective supports (see Fig; 7.1).

If the longitudinal bars spaced at a distance not exceeding 48 times the diameter of the tie are effectively tied in two directions, additional longitudinal bars in between these bars should be tied in one direction by open ties (see Fig 7.2)

Where the longitudinal reinforcing bars in a compression member are placed in more than one row, effective lateral support to the longitudinal bars in the inner rows may be assumed to have been provided if:
a) Transverse reinforcement is provided for the outermost row, and 
b) No bar of the inner row is closer to the nearest compression face than three times the diameter of the largest bar in the inner row (see Fig. 7.3).

Where the longitudinal reinforcing bars in compression member are grouped (not in contact) and each group adequately tied with transverse reinforcement, the transverse reinforcement for the compression member as a whole may be provided on the assumption that each group is a single longitudinal bar for purpose of determining the pitch and diameter of the transverse reinforcement. The diameter of such transverse reinforcement need not, however, exceed 20 mm (see Fig. 7.4).

A few examples of column ties are illustrated in Fig. 7.5. 

Pitch and Diameter of Lateral Ties 

Pitch-The pitch of the transverse reinforcement shall not be more than the least of the following distances (see Fig. 7.6A):

a) the least lateral dimension of the compression member,

b) sixteen times the smallest diameter of the longitudinal reinforcing bar to be tied, and

c) forty eight times the diameter of the transverse reinforcement.

Diameter -The diameter of the polygonal links or lateral ties shall not be less than one-fourth of diameter of the largest longitudinal bar, and in no case less than 5 mm. 

Helical Reinforcement (Spirally Reinforced) (see Fig. 7.6B)

Pitch – Helical reinforcement shall be of regular formation with the turns of the helix spaced evenly and its ends shall be anchored properly by providing one and a half extra turns of the spiral preferably with a 135 degrees hook. The pitch of the helical turns shall be not more than 75 mm or one-sixth of core diameter of the column, nor less than 25 mm or 3 times the diameter of steel bar forming helix. Tension lap length shall be provided at lap splices. 

Diameter -The diameter shall be not less than one-fourth of the diameter of the largest longitudinal bar, and in no case less than 5 mm.

Temporary Stirrups- At least two temporary fixing stirrups should be provided to splices in position (see Fig. 7.7) or to stiffen the helically bound columns during fabrication. It is better to detail and schedule such stirrups in the drawing. The stirrups coming above the floor shall not be removed until the next column is erected. 

Large Columns

Where reinforcement for very wide columns is to be fabricated in separate cages and erected in sections, they should be held together by at least 12 mm diameter bars spaced at double the stirrup spacing (see Fig. 7.8). Special requirements, if any, should be indicated by the designer.

Splicing of Column Reinforcement 

• General

Splicing is normally effected by the lapping of bars. The lengths of laps in the main bars shall conform to the values given in Section 4 (Tables 4.2 to 4.4). The bottom of the bars are normally at floor level. In exceptional cases, the bars may extend over more than one storey, provided that check is made to ensure that intersecting steel from beams, etc, can be placed through the column without difficulty, that the column reinforcement can be properly supported, and the concrete can be properly placed. Some of the bars terminating below floor level require separate splicing (see also Section 4). Typical splice details are shown in Fig. 7.9 (A to E) for both internal and external columns.

• Where a column at a particular floor is smaller (in cross-section) than the column immediately below it, the vertical bars from the lower column shall be offset to come within the upper column or dowel shall be used. The slope of the inclined portion shall not exceed 1 in 6. In detailing offset column bars, a bar diameter should be added to the desired offset; and in the corner of the square columns, the bars should be offset along the diagonal. 
• Longitudinal reinforcement bars in square or rectangular columns should be offset bent into the column above. Longitudinal bars in round columns where the column size is not changed should be offset bent if maximum number of bars are desired in the column above. The general practice is to sketch the offset for the corner bars which should be bent diagonally and make this the typical offset dimension for all the bars in the column. 
• For offset between column faces up to a maximum of 75 mm, the longitudinal bars should be offset bent. When the offset exceeds 75 mm, the longitudinal bars in the column below should be terminated at the floor slab and separate dowels used (see Fig 7.9 B and 7.9 D)
• Where adjoining beam is not provided, the height of the column equal to say 75 mm above the floor level should be cast along with the lower column so that a kicker can be formed to place the column shutters (see Fig. 7.9 C).

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• When the bar arrangement changes between floors, bars may extend through, stop off, or require separate dowels (Fig. 7.9B). Each situation requires its own solution. Steel equal to an area and bond capacity to that in the column above shall be extended. Column bars shall be spliced at the top of upstand beams, if available, rather than at floor level. 
• Where the column verticals are offset bent, additional ties/spirals shall be provided (see Fig. 7.10) and placed at a distance not more than 8 bar diameters from the point of the bend. For practical purpose, 3 closely spaced ties are usually used, one of which may be part of the regularly spaced ties plus two extra ties. The designer shall indicate on the drawing the general arrangement of vertical bars and all tie arrangements.
• The number of additional ties/spirals should be designed on the assumption that the horizontal thrust to be resisted shall be 1.5 times the horizontal components of the normal stress in the inclined portion of the bars. 
• Welded splice or other positive connections may be used as butt splices for vertical column bars instead of lapped splices. For bars of size 32 mm and above, such splices or connections may be used to avoid overcrowding of the bars due to extremely long laps which would otherwise be required. Special preparation of the ends of the vertical bars is usually required. Where bars are welded, the most common practice is to provide a square-cut end at the top and a double bevelled end on the bottom of the upper bar to rest on the square cut end (see Fig. 7.11). This permits filling the resulting space with weld metal to develop the splice. Where a welded sleeve or a mechanical device is used, both ends of the bar may be either square cut or standard shear cut, depending upon the type of connection used. Since the point of splice is to be staggered between alternate vertical bars and the splice location will depend upon the design requirements, the designer should indicate the types of splice permissible and their location on the drawing.

Bundled bars

Bundled bars shall be tied, wired or otherwise fastened to ensure that they remain in position. End-bearing compression splices should be held concentric, all bundles of column verticals should be held by additional ties at each end of end-bearing splices, and any short splice bars added for tension should be tied as part of the bundle within the limit of 4 bars in a bundle.: A corner of a tie should be provided at each bundle. 

Column in Flat Slabs

Mushroom heads are normally cast with the columns, and the details of reinforcement should be such that the steel can be formed into a separate cage. Therefore, it should be ensured that the column stirrups end below the mushroom head to enable a properly bonded cage to be positioned (see Fig. 7.12).

Note – The designer shall determine the amount of steel required in the mushroom to control cracks arising from the out-of-balance moments. 

Column-Beam Junction 

Typical details of a . column-beam junction are illustrated in Fig. 7.13. At column-beam intersections, it is better to avoid main beam bars clashing with main column bars. If splice bars are used (see Fig. 7.13), the beam cages may be prefabricated and splice bars placed in position after the beam reinforcement has been positioned in place. This also provides considerable scope for positioning support bars without resorting to cranking and avoiding intersecting beam and column reinforcement. However, this detail requires extra steel due to the additional laps. Where the beam does not frame into the column on all four sides to approximately the full width of the column, ensure that the stirrups are provided in the column for the full depth of the beam, or alternately, that special U-bars are detailed with the beam to restrain the column bars from buckling and to strengthen the concrete in compression. This is especially important where the floor concrete is of a weaker grade than the column concrete (see Fig. 7.14 and 7.15). In general, it is advisable to use U-bars at the non-continuous ends of beams of depth greater than 600 mm.

NOTE – It is important lo note that a joint by itself shall have a dependable strength sufficient to resist the most adverse load combinations sustained by the adjoining members as specified by the appropriate loading code. A higher factor of safety is sometimes necessary for joints. Design and detailing of the joint should be done 1o satisfy this condition. 

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Fig. 7.9 SPLICING OF COLUMN BARS AT INTERMEDIATE FLOORS

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Column with Corbel Joints 

Corbels

A corbel is a short cantilever beam (see Fig. 7.16) in which the principal load is applied in such a way that the distance between the line of action of the load and the face of the supporting member is less than 0.6d and the depth at the outer face of the bearing is greater than one-half of the effective depth at the face of the supporting member.

Main Reinforcement

The main tension reinforcement in a corbel should be not less than 0.4 percent and not more than 1.3 percent of the section at the face of the supporting member, and should be adequately anchored. 

Anchor the reinforcement at the front face of the corbel either by welding it to a transverse bar of equal strength or by bending back the bars to form loops; in either case, the-bearing area of the load should not project beyond the straight portion of the bars forming the main tension reinforcement (see Fig. 7.17 and 7.18). 

NOTE – The limitation on reinforcement percentages is based on the limited number of tests available. 

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Horizontal Force

When the corbel is required to resist a horizontal force in direction H applied to the bearing plate (see Fig. 7.19) because of shrinkage or temperature changes, provide additional reinforcement to transmit this force in its entirety. This reinforcement should be welded to the bearing plate and adequately anchored within the supporting member.

Shear Reinforcement

Provide shear reinforcement in the form of horizontal stirrups distributed in the upper two-thirds of the effective depth of the corbel at the column face. This  reinforcement should have an area of at least one- half of the area of the main tension reinforcement and should be adequately anchored (see Fig. 7.19). 

Detailing of Reinforcement

Columns should be detailed by means of enlarged views. Indicate the levels of the bottom (top of bars at floor level) and top of the column (at top of slab or beam or upstand beam) and the floor height, if necessary. Indicate on the schedule the positions of all intermediate beams. Show each bar mark once, and provide adequate sections showing all main bars and the arrangement of stirrups. Keep in view the effect of providing kickers on levels.

 

Foundations

Types of Foundations

The following are types of reinforced concrete foundations, the particular type being chosen depending on the magnitude and disposition of the structural loads, and the bearing capacity of the ground. 

a) Individual Column Footing – Generally square in plan but sometimes rectangular or circular.

b) Combined Footing – Combined footing is a common footing to two or more columns in a line. The placing of reinforcement depends on the shape of the bending moment and shear force diagrams considering the soil pressure and the column loads on the footing.

c) Strip Footings – Under columns or walls.

d) Raft Foundation – Covering the whole plan area of structure, detailing being similar to 2-way reinforced solid floor slabs or flat slabs.

e) Pile Foundations – This includes detailing of pile cap and pile portion.

Cover

The minimum thickness of cover to main reinforcement shall not be less than 50 m.m for surfaces in contact with earth face and not less than 40 mm for external exposed face. However, where the concrete is in direct contact with the soil, for example, when a levelling course of lean concrete is not used at the bottom of footing, it is usual to specify a cover of 75 mm. This allows for the uneven surface of the excavation. In case of raft foundation, whether resting directly on soil or on lean concrete, the cover for the reinforcement shall not be less than 75 mm. 

Minimum Reinforcement and Bar Diameter 

The minimum reinforcement according to slab and beam elements as appropriate should be followed, unless otherwise speci P led. The diameter of main reinforcing bars should be not less than 10 mm. 

Detailing Methods 

Foundations should normally be detailed diagrammatically in plan and elevation. 

In case of plan, show diagrammatically the location of foundation reinforcement (similar to slabs) as well as starter bars and stirrups (as for columns). It is preferable for column and wall dowels (starter bars) and the foundation reinforcement to be shown on the same drawing.

In case of elevation, show diagrammatically the location of reinforcement as for beams. In case of pile foundation. detailing of pile is similar to that of columns and detailing of the pile cap supported on piles is similar to that of footing. An indication of the type of soil and its assumed bearing capacity may be specified in the drawing.

Individual Footings 

Individual footings (see Fig. 6.1) are generally square and support a central column. Rectangular footings can be used when the space is restricted in one direction. Individual footings of circular and other shapes can also be used. Figure 6.1 gives typical details of 2 column footing.

Reinforcement Requirements:

Total tensile reinforcement shall be distributed across the corresponding resisting section as given below: 

1. In one-way reinforced footing, the reinforcement shall be distributed uniformly across the full width of the footing.
2. In two-way reinforced square footing, the reinforcement extending in each direction shall be distributed uniformly across the full width of the footing.
3. In two-way reinforced rectangular footing. the reinforcement in the long direction shall be distributed uniformly across the full width of the footing. For reinforcement in the short direction, a central band equal to the width of the footing shall be marked along the length of the footing and portion of the reinforcement determined in accordance with the equation given below shall be uniformly distributed across the central band: 

The remainder of the reinforcement shall be uniformly distributed in the outer portions of the footing. 

Figure 6.2 illustrates placing of transverse reinforcement for rectangular footing. 

Vertical reinforcement or dowels

Extended vertical reinforcement or dowels of at least 0.5 percent of the cross-sectional area of the supported column or pedestal with a minimum of 4 bars of 12 mm diameter shall be provided. Where dowels are used, their diameter shall not exceed the diameter of column bars by more than 3 mm.

Column bars of diameter larger than 36 mm in compression can be dowelled at the footings with bars of smaller size oi the necessary area. The dowel shall extend into the column a distance equal to the development length of the column bar, and into the footing a distance equal to the development length of the dowel. The development length shall be calculated in accordance with 4.4.2.

For method of detailing see Fig. 6.1.
Note- Where the depth of the footing or footing and pedestal combined is less than the minimum development length in compression required fol dowels (starter bars) of a certain size, the size of dowels (starter bars) may be suitably decreased and the number of dowels increased to satisfy the required area and development length.

To achieve economy, the footings are sloped or stepped towards the edge satisfying the requirements for bending and punching shear. In sloped footing, the slope is generally restricted such that top formwork is not called for in construction. The thickness at the edges shall not be less than 15 cm for footings on soils, nor less than 30 cm above tops of piles in case of footing on piles. 

Combined Footings

• Combined footings become necessary where the external columns of the structure are close to the boundary of an existing structure and also where the footings of individual columns overlap one another. Such foundations (supporting more than one column/pedestal or a continuous wall) shall be proportioned to resist the design loads and individual reactions, in accordance with appropriate design requirements. The detailing requirements as specified in Section 4 for slabs and beams shall be followed as appropriate. 
• Detailing
  • For combined footing, detailing of longitudinal and transverse bars is similar to that of beams.
• Column on edges of footing
  • To prevent shear failure along the inclined plane (corbel type of failure) in footing, where a column is located on the edge, it is advisable to provide horizontal U-type bars around the vertical starter bars. These bars shall be designed for every such column (see Fig. 6.3).

Figure 6.4 (A, B and C) shows typical arrangement of bars in combined footings.

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Continuous Footing Under Walls

In continuous wall foundations, transverse reinforcement should be provided when the projection of the footing beyond the wall exceeds the thickness of the footing (see Fig. 6.5). It is also recommended that longitudinal reinforcement be provided wherever an abrupt change in the magnitude of the load or variation in ground support or local loose pockets may occur along the footing.

 

Raft Foundations

A raft is a foundation unit continuous in two directions, covering an area equal to or greater than the base area of the building. If the raft consists of several parts with varying loads and heights, it is advisable to design the raft with expansion joints between these parts. Joints shall also be provided wherever there is a change in the direction of the raft and should be detailed on the drawing. The detailing requirements as specified in Section 4 for beams and columns may be followed as appropriate. 

Minimum reinforcement in either direction shall not be less than 0.15 percent of the gross sectional area for mild steel reinforcement and 0.12 percent in case of high strength deformed bars.

Detailing

For raft foundation, detail both the longitudinal and transverse bars generally in accordance with the rules for slabs and beams except cover and bar supports. While detailing reinforcement in raft foundation. construction method and sequence of construction are to be specified which should include the following:

1. Position of construction joints,
2. Position of movement joints, and
3. Position of water bar joints.

The location of lap splices in raft should be detailed with care as the direction of bending will differ from suspended members.

Placing of Bar Supports

Where top reinforcement is required, consideration should be given to the method of supporting this with chairs and edge U-bars. This must be carried out in accordance with the specification for the job and should take into account construction sequence. weight of top steel and depth of foundation. The suggested spacing of supports i.e 30 times the diameter of supporting bars using chairs having diameter of at least 12 mm. I the diameter of chairs should be such that the), do not bend or buckle under the weight of reinforcement and other incidental loads during construction.

Ducts and Trenches

Where ducts and trenches occur in rafts, special attention should be given to detailing continuity of top reinforcement. specially where moment transfer is required (see Fig. 6.6).

Pile Foundation

• Driven Precast Concrete Pile

a) The longitudinal reinforcement shall be provided in precast reinforced concrete piles for the entire length. All the main longitudinal bars shall be of the same length with lap welded at joints and should fit tightly into the pile shoe if there is one. Shorter rods to resist local bending moments may be added but the same should be carefully detailed to avoid any sudden discontinuity of the steel which may lead to cracks during heavy driving.

The area of main longitudinal reinforcement shall not be less than the following percentages of the cross-sectional area of the piles:

1) For piles with length less than 30 times the least width- 1.25 percent.

2) For piles with length 30 to 40 times the least width- 1.5 percent.

3) For piles with length greater than 40 times the least width- 2 percent.

b) The lateral reinforcement is of particular importance in resisting the driving stresses induced in the piks and should be in the form of hoops or links and of diameter not less than 6 mm. The volume of lateral reinforcement shall not be less than the following (see Fig. 6.7):

1) At each end of the pile for a distance of about 3 times the least width-not less than 0.6 percent of the gross volume of that part of the pile; and

2) In the body of the pile-not less than 0.2 percent of the gross volume of pile.

The spacing shall be such as to permit free flow of concrete around it. The transition between the close spacing of lateral reinforcement near the ends and the maximum spacing shall be gradually over a length of 3 times the least width of the pile. 

The cover of concrete over all the reinforcement including ties should not be less than 40 mm. But where the piles are exposed to seawater or water having other corrosive content, the cover should be nowhere less than 50 mm.

Piles should be provided with flat or pointed coaxial shoes if they are driven into or through ground, such as rock, coarse gravel, clay with cobbles and other soils liable to damage the concrete at the tip of the pile. The shoe may be of steel or cast iron. Shapes and details of shoca depend on the nature of ground in which the pile is driven. In uniform clay or sand the shoe may be omitted.

Where jetting is necessary for concrete pilu, a jet tube may be cast into the pile, the tube being connected to the pik shoe which is provided with jet holes. Generally, a central jet is inadvisable, as it is liable to become choked. At least two jet holes will be necessary on opposite sides of the shoe, four holes give best results. Alternatively, two or more jet pipes may be attached to the sides of the pile.

Reinforcement requirement

A pile shall be reinforced in the same way as the column, with the main bars on the periphery and secondary bars (binders or links) around main bars. In addition the main bars shall be bent inwards at the lower end and welded to the shoe made of chilled cast iron or steel.

Spacer bars

To ensure the rigidity, pile spacer bars shall be used as shown in Fig. 6.8. The spacer bars or forks can be of cast iron, pressed steel or a length of steel pipe with slotted ends to fit the main reinforcing bars. They can be detailed on the drawing, at 1.5 m centres along the full length of the pile. The fork may be placed diagonally at each position across the section as shown in Fig. 6.8.

• Cast-in-situ Piles or Bored Piles

Reinforcement requirement

The design of the reinforcing cage vary depending upon the driving and installation conditions, the nature of the subsoil and the nature of load to be transmitted by the shaft. that is. axial or otherwise. The minimum area of longitudinal reinforcement (mild steel or deformed bars) within the pile shaft shall be 0.4 percent of the sectional area calculated on the basis of outside area of casing of the shaft.

The curtailment of reinforcement along the depth of the pile. in general, depends on the type of loading and subsoil strata. In case of piles subject to compressive load only, the designed quantity of reinforcement may be curtailed at appropriate level according to the design requirements. For piles subjected to uplift load, lateral load and moments, separately or with compressive loads. it may be necessary to provide reinforcement for the full depth of pile. In soft clays or loose sands, or where there is likelihood of danger to green concrete due to driving of adjacent piles. the reinforcement should be provided up to the full pile depth with lap welds at joints regardless of whether or not it is required from uplift and lateral load considerations. However, in all cases. the minimum reinforcement should be provided in the full length of the pile.

Piles shall always be reinforced with a minimum amount of reinforcement as dowels, keeping the minimum bond length into the pile shaft and with adequate projection into the pile cap.

Clear cover to all main reinforcement in pile shaft shall be not less than 50 mm. The laterals df a reinforcing cage may be in the form of links or spirals. The diameter and spacing of the same is chosen to impart adequate rigidity to the reinforcing cage during its handling and installations. The minimum diameter of the links or spirals shall be 6 mm and the spacing of the links or spirals shall be not less than 150 mm.

Under-reamed Piles

The minimum area of longitudinal reinforcement in stem should be 0.4 percent. Reinforcement is to be provided in full length. Transverse reinforcement shall not be less than 6 mm diameter at a spacing of not more than the stem diameter or 300 mm whichever is less. In under-reamed compaction piles, a minimum number of four 12-mm diameter bars shall be provided. For piles of lengths exceeding 5 m and of 375 mm diameter, a minimum number of six 12-mm bars shall be provided. For piles exceeding 400 mm diameter, a minimum number of six 12-mm bars shall be provided. The circular stirrups for piles of lengths exceeding 5 m and diameter exceeding 375 mm shall be minimum 8-mm diameter bars.
The minimum clear cover over the longitudinal reinforcement shall be 40 mm. In aggressive environment of sulphates, etc. it may be increased to 75 mm. 

Figure 6.9 gives typical details of a bored cast-in-situ under-reamed pile foundation.

• Pile Caps

The pile cap usually supports column and this is positioned at the centre of gravity of the pile group, so the pile cap incorporates column dowel bars in exactly the same way as provided in column bases. Allowance shall be made in length and width of the cap to allow for piles being slightly out of true position after being driven.

General consideration

• The pile cap along with the column pedestal shall be deep enough to allow for the necessary anchorage of the column and pile reinforcement. Although they are assumed to act as a simply supported beam and are designed for the usual conditions of bending moment and shear force, there is a tendency to fail in bursting due to high principal tension. This should be resisted by reinforcement going around outer piles in the group (usually # 12 @ 150).
• Generally adopted configuration for pile caps along with plan arrangement of reinforcement details are shown in Fig. 6.10.
• The clear overhang of the pile cap beyond the outermost pile in the group shall normally be 100 to I50 mm, depending upon the pile size.

• A levelling course of plain concrete of about 80 mm thickness may be provided under the pile caps, as required.
• The clear cover for the main reinforcement for the bottom of cap shall not be less than 60 mm. 
• The reinforcement from the pile should be properly tied to the pile cap.
• A typical arrangement of bars in a pile cap supporting a column between two piles is illustrated in Fig. 6.1 I and typical details of a pile cap resting on 3 piles is illustrated in Fig. 6.12.

Grade Beams

• The grade beams supporting the walls shall be designed taking due account of arching effect due to masonry above the beam. The beam with masonry behaves as a deep beam due to composite action.
• The minimum overall depth of grade beams shall be 150 mm. The reinforcement at the bottom should be kept continuous and an equal amount may be provided at top to a distance of quarter span both ways from pile or footing centres as the case may be. The longitudinal reinforcement both at top and bottom should not be less than three bars of 10 mm diameter (mild steel) and stirrups of 6 mm diameter bars spaced at a maximum spacing of 300 mm (see Fig. 6.13).
• In expansive soils, the grade beams shall be kept a minimum of 80 mm clear off the ground. In other soils.‘beams may rest on ground over a levelling concrete coarse of about 80 mm (see Fig. 6.14).
• In case of exterior beams over piles in expansive soils, a ledge projection of 75 mm thickness and extending 80 mm into ground (see Fig. 6.14), shall be provided on outer side of beams.

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General Detailing Requirements

Cover

Reinforcement shall have concrete cover (nominal) and the thickness of such cover (exclusive of plaster or other decorative finish) shall be as follows:

1. At each end of reinforcing bar not less than 25 mm, or twice the diameter of such bar whichever is greater;
2. For a longitudinal reinforcing bar in a column not less than 40 mm or the diameter of such bar whichever is greater. In the case of columns with a minimum dimension of 20 mm or tinder, whose reinforcing bars do not exceed 12 mm, the cover may be reduced to 25 mm;
3. For longitudinal reinforcing bar in a beam not less than 25 mm or the diameter of such bar, whichever is greater;
4. For tensile, compressive, shear or other reinforcement in a slab not less than I5 mm or the diameter of such reinforcement, whichever is greater; and
5. For any other reinforcement not less than 15 mm or the diameter of such reinforcement, whichever is greater.

Note – The values of cover suggested are nominal cover as specified in the drawings. The cover shall in no case be reduced by more than one-third of the specified cover or 5 mm whichever is less. During construction it is essential to ensure that these tolerances are met.

• Increased cover thickness may be provided when the surfaces of concrete members are exposed to the action of harmful chemicals (as in the case of concrete in contact with earth contaminated with such chemicals), acid, vapour, saline atmosphere, sulphurous smoke (as in the case of steam-operated railways), etc, and such increase of cover may be between I5 and 50 mm over the values given in 4.1 above as may be specified by the Engineer-in-Charge. However, in no case cover should exceed 75 mm. 
• For reinforced concrete members of marine structures totally immersed in seawater, the cover shall be 40 mm more than that specified in 4.1, but total cover should not exceed 75 mm. 
• For reinforced concrete structures/ structural members, periodically immersed in seawater or subject to sea spray, the cover of concrete shall be 50 mm more than that specified in 4.1, but total cover should not exceed 75 mm. 
• For concrete of grade M25 and above, the additional thickness of cover specified in 4.1.1 to 4.1.3 may be reduced by half. 

Development of Stress in Reinforcement

• Development Length of Bars in Tension or Compression – The calculated tension or compression in any bar at any section shall be developed on each side of the section by an appropriate development length or end anchorage or by a combination thereof.

Note – Development length is the embedded length of reinforcement required to develop the design strength of the reinforcement at a critical section. Critical section for development of reinforcement in flexural members are at points of maximum stress and at points within the span where adjacent reinforcement terminates, or is bent. Provisions of 4.6.3 (c) should be satisfied at simple supports and at points of inflection.

• Design bond stress in limit state design method for plain bars in tension shall be as follows: 

For deformed bars, these values shall be increased by 60 percent. For bars in compression, the values of bond stresses for bars in tension shall be increased by 25 percent. 

Anchoring Reinforcing Bars 

It is important to note that when a bar is subjected to both tension and compression, the anchorage value should correspond to the one which gives the maximum value, and at the same time individual requirements (with respect to tension and compression) are also satisfied as specified in 4.3.1 to 4.3.3.

• Anchoring Bars in Tension 

Deformed bars may be anchored in straight lengths (without end anchorages), provided the development length requirements are satisfied. Plain bars should not be normally anchored through straight lengths alone and should be provided with hooks.

Bends and hooks 

a) Bends – The anchorage value of a standard bend shall be taken as 4 times the diameter of the bar for each 45 degree bend subject to a maximum of 16 times the diameter of the bar.

b) Hooks – The anchorage value of a standard U-type hook shall be equal to 16 times the diameter of the bar. 

The anchorage values of standard hooks and bends for different bar diameters are given in Table 4.1. 

• Anchoring Bars in Compression

The anchorage length of straight bar m compression shall be equal to the development length of bars in compression as specified in 4.2.2. The projected length of hooks, bends and straight lengths beyond bends, if provided for a bar in compression, should be considered for development length (see Fig. 4.1).

• The development length values for fully stressed bars in tension as well as compression based on 4.2.2 are given in Tables 4.2, 4.3 and 4.4.

NOTE- If the amount of steel provided at a design section is more than that required from design consideration, the development length given in Tables 4.2, 4.3 and 4.4 may be modified as: 

Unless otherwise specified, Ldm modified development length should be used in detailing reinforcement.

• Mechanical Devices for Anchorage – Any mechanical or other device capable of developing the strength of the bar without damage to concrete may be used as anchorage with the approval of the Engineer-in-Charge. 
• Anchoring Shear Reinforcement 

a) Inclined bars – The development length shall be as far bars in tension; this length shall be measured as under:

1. In tension zone, from the end of the sloping or inclined portion of the bar (See Fig. 4.2A), and
2. In the compression zone, from the mid depth of the beam (see Fig. 4.2B). 

b) Stirrups and ties-Not withstanding, any of the provisions of this Handbook, in case of secondary reinforcement, such as stirrups and transverse ties, complete development length and anchorage shall be deemed to have been provided when the bar is bent through an angle of at least 90 degree round a bar of at least its own diameter and is continued beyond the end of the curve for a length of at least eight diameters, or when the bar is bent through an angle of 135 degree and is continued beyond the end of the curve for a length of at least six bar diameters or when the bar is bent through an angle of 180° and is continued beyond the end of the curve for a length of at least four bar diameters. 

• Special Members

Adequate end anchorage shall be provided for tension reinforcement in flexural members where reinforcement stress is not directly proportional to moment, such as sloped, stepped or tapered footings, brackets, deep beams and members in which the tension reinforcement is not parallel to the compression face. 

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Reinforcement Splicing

• Splicing is required to transfer force from one bar – t,o another. Methods of splicing include lapping (see 4.4.2), welding and mechanical means (see – 4.4.3)
• Where splices are provided for continuity in the reinforcing bars (tension bars in beams), they shall be as far as possible away from the sections of maximum stress and be staggered. It is recommended that splice in flexural members should not be at sections where the bending moment is more than 50 percent of the moment of resistance of the section. Not more than half the bars shall & spliced at a section.
• Where more than one half of the bars are spliced at a section or where splices are made at points of maximum stress, special precautions shall be taken, such as increasing the length of lap and/or using spirals or closely spaced stirrups around the length of the splice.

Note 1 – The stirrups provided should be able to resist a tension equal to the full tensile force in the lapped bars and should be provided in the outer one-third of the lap length at both ends with at least three stirrups on either side (see Fig. 4.3). In case of thick bars (say diameter > 28 mm), lap splices should be completely enclosed by transverse reinforcement, for example, in the form of small compact stirrups or spirals [see Fig. 4.4 (A and B)].

Note 2 – Careful detailing is necessary when reinforcements are to be spliced. Therefore location and details of splices should be determined at the design stage itself and indicated in the drawing. Preferably splicing details should not be left to be decided at the site of construction. 

Lap Splices 

1. Diameter of bars for lap splicing – Lap splices shall not be used for bars larger than 36 mm. For larger diameters, bars may be welded (see Appendix A). In cases where welding is not practicable, lapping of bars larger than 36 mm may be permitted, in which case additional spirals should be provided around the lapped bars (see Fig. 4.4A).
2. Staggering of lap splices – Lap splices shall bc considered as staggered if the centre-to centre distance of the splices is not less than 1.3 times the lap length (see Fig. 4.5) calculated as given in (c) below. Bars could be lapped vertically one above the other or horizontally, depending upon the space requirement.
3. Lap length in tension – Lap length including anchorage value of hooks in flexural tension shall be Ld or (30 x diameter) whichever is greater and for direct tension 2 Ld or (30 x diameter) whichever is greater. The straight length of the lap shall not be less than (15 x diameter) or 200 mm, whichever is greater (see Fig. 4.6).

where Ld= development length

Note- Splices in direct tension members shall be enclosed in spirals made of bars not less than 6 mm in diameter with pitch not more than IO cm. Hooks/bends shall be provided at the end of bars in tension members (see Fig. 4.4C). 

4. Lap length in compression – The lap length in compression shall be equal to the development length in compression calculated as in 4.2.2 (see Tables 4.2, 4.3 and 4.4), but not less than 24 x diameter.

5. Requirement of splice in a column – In columns where longitudinal bars are offset at a splice, the slope of the inclined portion of the bar with the axis of the column shall not exceed 1 in 6, and the portions of the bars above and below the offset shall be parallel to the axis of the column. Adequate horizontal support at the offset bends shall be treated as a matter of design, and shall be provided by metal ties, spirals, or parts of the floor construction. Metal ties or spirals so designed shall be placed near (not more than 8 x diameter) from the point of bend. The horizontal thrust to be resisted shall be assumed as 1.5 times the horizontal component of the nominal force in the inclined portion of the bar (see Fig. 4.7). Offset bars shall be bent before they are placed in the forms. Where column faces are offset 75 mm or more, splices of vertical bars adjacent to the offset face shall be made by separate dowels overlapped at specified about.

Note – It is to be noted that in Fig. 4.7. additional stirrups will be required only near the bottom crank.

6. Bars of different diameters – When bar of two different diameters are to be spliced, the lap length shall be calculated on the basis of diameter of the smaller bar.

Lap splices in welded wire fabric: 

1. The fabric is supplied in long mats/rolls and it is rarely necessary to have a joint of the main wires. The rigidly connected cross-members provide mechanical anchorage. Adequate lapping where necessary may be provided with a comparatively short lap when cross wires occur within the lap.
2. In structural slabs, laps in regions of maximum stress shall be avoided. Such splices, where used for either end or edge laps. shall be made so that the distance between outermost cross wires is not less than the spacing of the wire parallel to the lap plus 100 mm (see Fig. 4.6).
3. In other cases for end laps, welded wire fabric shall be lapped not less than one mesh plus 50 mm, that is, the length of the lap shall be 50 mm greater than the spacing of wires parallel to the lap. For edge laps, a lap of 50 mm is sufficient (see Fig. 4.6).
4. These requirements for lapping should be covered by suitable notes in the general specifications. But whether specified by wordings or shown on plans, certain dis- tinction should be made between ‘edge laps’ and ‘end laps’.
5. The width of an edge lap shall be indicated as the centre-to-centre distance between the outside of longitudinal salvage wires of the overlapping sheets as illustrated in Fig. 4.6.
6. The length of an end lap shall be indicated as the top-to-top distance between the ends of the longitudinal wires of the overlapping sheets.

Welded Splices and Mechanical Connections:

Where the strength of a welded splice or mechanical connection has been proved by tests to be at least as great as that of the parent bar, the design strength of such connections shall be taken as equal to 80 percent of the design strength of the bar for tension splice and 100 percent of the design strength for the compression splice. However, 100 percent of the design strength may be assumed in tension when the spliced area forms not more than 20 percent of the total area of steel at the section and the splices are staggered at least 600 mm centre-to-centre.

The choice of splicing method depends mainly on the cost, the grade of steel, the type of reinforcement, generally high bonding, the possibility of transferring compressive and/ or tensile stresses and the available space in the section concerned. The designer shall specify the splicing method and the conditions under which it is to be carried out.

Mechanical coupling devices shall be arranged so that as small a number as possible affect a single section.They should, in addition, be placed outside the most highly stressed sections.

Sleeve splicing – If correctly used, sleeve connections may transmit the total compressive or tensile stress. In general, the use of these sleeves is governed by various conditions laid down in the agreement for the method or, in the absence of recommendations, by preliminary testing.

During assembly, particular care shall be taken to ensure that the lengths introduced into the sleeve are sufficient. 

These lengths should be marked before hand on the ends of the bars to be spliced except when a visual check on penetration is possible (for example, sleeve with a central sight hole):

a) Threaded couplers (see Fig. 4.8)

In order to prevent any decrease in the end sections of the bar as a result of threading (with V- form or round threads), they can be: 

1) upset;

2) for long units, fitted with larger section threaded ends by flash welding; or

3) fitted with a threaded sleeve by crimping.

Another solution consists of threading the ends but only taking into consideration the nominal section of the threaded end, that is, reducing the permissible stress in the reinforcement.

The ends of the sleeve shall be slightly reduced in section, in order to prevent overstressing of the first few threads.

There are, at present, reinforcing bars with oblique, discontinuous., spiral ribs, allowing splicing with a special sleeve with internal threads.

This same process is used to splice prestressing bars, and in order to prevent confusion between reinforcing bars and prestressing steels, the direction of threading is reversed (see Fig. 4.9). 

Two lock nuts. tightened on each side of the sleeve into which the reinforcing bars are introduced to the same depth, prevent -any accidental unscrewing due to slack in the threads (splices not under tension). The nuts are tightened with a torque wrench. This device is also used for splicing prefabricated elements. These joints are generally 100 percent efficient under both tension and compression. To decrease the itt-siru operations. one of the ends is generally fitted with its sleeve in advance and the other bar to be joined with the sleeve should remain manoeuvrable until the splice has been made (see Fig. 4. 10)

b) Coupling with a crimped sleeve

Crimped sleeves constitute a method of splicing limited to relatively large diameter deformed reinforcing bars. It consists of the introduction of the bars to be spliced into a sleeve which is crimped by means of a hydraulic crimping tool onto the ribbed bars in order to fill the voids between them and the inner surface of the sleeve. The ribs on the bar penetrate into the relatively softer steel of the sleeve and the ribs work in shear.

During crimping the sleeve lengthens, and the other reinforcing bar to be spliced should be displaceable at this moment. The size of the crimping device requires a bar interspacing of at least 10 cm (see Fig. 4.11). Splicing by crimping is also possible with reinforcing bars of differing diameter. The same method also enables threaded steel rods to be spliced to reinforcing bars using high strength threaded bolts (see Fig. 4.12).

c) Coupling with injected sleeves

These couplings are a special case of sleeve splicing; the stresses are distributed by the shear strength of the product injected between the ends of the bars to be sleeve spliced:

1)With the ‘Thermit’ sleeve the space between the deformed bars and the sleeve, whose internal surface is also ribbed, is tilled with a special molten metal. This molten metal is prepared in a crucible, which is in communication with the sleeve, by igniting a mixture consisting mainly of iron oxide and aluminium powder. The strength of the sleeve may be increased by using a larger sleeve diameter (see Fig. 4.13).

The sleeve is shorter ‘but wider than that used in the crimping method. The bars are not in contact.

The splice may be made in any direction as long as space allows the crucible to be put into place.

2) Similar method is the injection of grout or an epoxy resin between the sleeve and the bars. The length of the sleeve is necessarily greater (see Fig. 4.14). 

d) Butt splices – For this purpose open flanged sleeves made from steel strip can be used. They are tightened onto the bars by the introduction of a flat tapered wedge (see Fig. 4.15).

The end sections, in contact within the device, shall be perfectly at right angles to the axis of the spliced bars.

Another method involves the use of 4 small diameter ribbed bars which are tightened, using pliers, with 3 ring-clamps. The advantage of this method, in comparison to the previous one, is the fact that it allows a portion of the tensile stress to be taken up.

For bars with ribs in the form of a thread, a butt splice may be made with a sleeve, but with greater facility.

There are also sleeves consisting of a metallic cylinder, the internal diameter of which fits the bars to be spliced. This sleeve is fixed to one of the reinforcing bars by a few welding points: a hole at the centre of the sleeve enables one to check that there is contact between the bars. This economical method of splicing, which is easy to apply, can only transmit compressive stresses. 

Main advantages and disadvantages of mechanical coupling:

1. The use of mechanical couplers is frequently justified when space does-not allow lapping, although crimping and tightening tools require accessibility which may reduce this advantage.
2. This splicing method often requires more careful cutting of the reinforcing bar, a check which is more difficult than in the case of lapping;it also requires the use of reinforcing bars of the same diameter, and mobility of one of the two bars to be spliced.
3. Good performance of the splice is not endangered special atmospheric conditions as in welding.
4. The cost of equipment and its use limit this method to exceptional cases only. 

NOTE- Some mechanical methods of splicing of reinforcement which are in vogue in this country make use of the following principles:

a) A special grade steel sleeve is swaged on to reinforcing bars to be joined with the help of a portable hydraulically operated bar grip press either at site or at stocking yard.

b) Two sleeves with threaded ends are drawn together by an interconnecting stud. These sleeves are then swayed on to the reinforcing bars either at site or at the stocking yard.

Hooks and Bends

• Hooks and bends, and other anchorage of reinforcement in reinforced concrete shall be of such form, dimensions and arrangement as will ensure their adequacy without over-stressing the concrete or steel.
• Where normal hooks are used. they should be of U-type or L-type; but usually U-type is preferred for mild steel bars and L-type for deformed bars. If the radius of the bend or hooks conforms to that of the standard hooks or bends in longitudinal bars, the bearing stresses inside the bend in concrete need not be checked.

a) Bearing stresses at bends – The bearing stress in concrete for bends/ hooks in stirrups and ties conforming to 4.3.5(b) need not be checked as there is a transverse bar at each bend. The bearing stress inside a bend in all other cases should preferably be calculated as given in the following formula (see Fig. 4.16). The most dangerous situation is that of a bar, the layout of which is parallel to a surface or wall. Safety can be substantially increased by inclining the curve zone towards the mass of concrete wherever possible, a condition which frequently occurs in anchoring. However, it may be noted that IS: 456-1978 also exempts check for bearing stress in concrete for standard hooks and bends described in Table 4.1.

Characteristic strength of concrete and for a particular bar or group of bars in contact shall be taken as a centre-to-centre distance between bars or groups of bars perpendicular to the plane of the bend (mm); for a bar or group of bars  adjacent to the face of the member, a shall be taken as the cover plus size of bar.

In other words, the minimum radius of the bend, r, should be such that

When the large steel stresses need to be developed il. ‘he bend, radial bearing stresses in the concrete may become excessive. The above equation controls the diameter of bend when there is a combination of high tensile stress in the bend. large bar diameter and low concrete strength. To simplify the application of the above formula minimum radius of bend is given in Table 4.5 for different grades of concrete and steel.

b) If a change in direction of tension or compression reinforcement induces a resultant force acting outward tending to split the concrete, such force should be taken up by additional links or stirrups. Accordingly in structural components with curved or angled soffits, or those formed with bends or corners, it should be ensured that the radial tensile forces due to changes in the direction of reinforcement are resisted by additional links (see Fig. 4.17). Bent tension bar at a re-entrant angle should be avoided.

c) The minimum straight length of hook is four times the bar diameter. For small diameter bars this should be a minimum of 5O’mm in order to facilitate holding the bar in place while forming the hook. The hooks when formed are quite large and while detailing it is important to ensure that they do not foul with other reinforcement, particularly where beams have more than one row of bars.

d) Reinforcing bars shall be so detailed that the hooks are not positioned in tensile zones of concrete as this may cause cracking. It is better to bend the bars so that the hooks and bars terminate in compression zones or so lengthen the bars to eliminate the need for hooks.

Curtailment of Tension Reinforcement in Flexural Members 

• For curtailment, reinforcement shall extend beyond the point at which it is no longer required to resist flexure for,a distance equal to the effective depth of the member or 12 times the bar diameter, whichever is greater, except at simple support or end of cantilever. Figures 4.18 to 4.21 illustrate the requirement at cut-off point and at supports in flexural members.

Note 1 – A point at which reinforcement is no longer required to resist flexure is where the resistance moment of the section, considering only the continuing bars, is equal to the design moment.

Note 2 -The points at which reinforcement can be curtailed is to be based\ on the bending moment envelope developed by the designer. It should be noted that the use of envelope helps in achieving better design. A typical bending moment envelope considering various loading conditions is given in Fig. 4.22.

Figure 4.23 gives a standard bending moment diagram (based on uniformly distributed load) to enable designers to choose locations for curtailment of reinforcement. 

Flexural reinforcement shall not, preferably, be terminated in a tension zone unless any one of the following conditions is satisfied:

1. The shear at the cut-off point does not exceed two-thirds that permitted, including the shear strength of web reinforcement provided.
2. Stirrup area in excess of that required for shear and torsion is provided along each terminated bar over a distance from the cut- off point equal to three-fourths the effective depth of the member. The excess stirrup area (sq.mm) shall be not less than 0.4 bs/fy, where b is the breadth of beam (mm), s is the spacing (mm) and fy is the characteristic strength of reinforcement (N/sq.mm). The resulting spacing shall not exceed (d/8)Bb , where Bb is the ratio of the area of bars cut-off to the total area of bars at the section and d is the effective depth.
3. For 36 mm and smaller bars, the continuing bars provide double the area required for flexure at the cut-off point and the shear does not exceed three-fourths that permitted. 

Positive Moment Reinforcement

a) At least one-third the maximum positive moment reinforcement in simple members and one-fourth the maximum positive moment reinforcement in continuous members shall extend along the same face of the member into the support, to a length equal to Ld/3 (see Fig. 4.18). where Ld is the development length based on fully stressed bars. This is required to provide for some shifting of the moment due to changes in the loading, settlement of supports, lateral loads and other causes.

b) When a flexural member is part of a primary lateral load resisting system, the positive reinforcement required to be extended into the support according to (a) shall be anchored to develop its design stress (fully developed stress) in tension at the face of the support (see Fig. 4.19). This anchorage is to assure ductility of response in the event of unexpected over- stress such as from an earthquake. It is not sufficient to use more reinforcement at lower stresses. The full anchorage requirement does not apply to any excess reinforcement over and above that provided at the support.

At simple supports and at points of inflection, positive moment tension reinforcement shall be limited to a diameter such that Ld does not exceed (see Fig. 4.18)  

is not satisfied, the designer should either reduce the diameter of bars, whereby Ld is reduced, or increase the area of positive reinforcement at the section considered, whereby M1 is increased, or resort to botli the steps. 

Negative Moment Reinforcement

At least one-third of the total tension reinforcement provided for negative moment at the support shall extend beyond the point of inflection (PI) not less than the effective depth of the member or 12 x diameter or one-sixteenth of the clear span, whichever is greater (see Fig. 4.20 and 4.21). 

Spacing of Reinforcement

For the purpose of this clause, the diameter of a round bar shall be its nominal diameter, and in the case of bars which are not round or in the case of deformed bars or crimped bars, the diameter shall be taken as the diameter of a circle giving an equivalent effective area. Where spacing limitations and minimum concrete cover are based on bar diameter, a group of bars bundled in contact shall be treated as a single bar of diameter derived from the total equivalent area. 

Bars Bundled in Contact 

General – Bars in pairs, or in groups of 3 or 4 tied together and in contact side by side (bundled bars) may be used in beams and columns. This has been the practice in USA for many years, and is now permitted in most countries including India.

As bundled bars provide more reinforcement in less space than do single bars, it is possible to reinforce a member more heavily and still get better compaction of concrete. Beam and column sizes can thus often be reduced with saving in cost.

Bundled bars shall not be used in members without stirrups. Bundled bars shall be tied together to ensure the bars remain together as a bundle. Bars larger than 36 mm diameter shall not be bundled except in columns.

Whenever bar spacing limitations, minimum cover, tie size and spacing are based on bar diameter, a group of bars bundled in contact shall be treated as a single bar of diameter derived from the total equivalent area (see Table 4.6). However, the cover provided should be measured from the actual outside contour of the bundle.

Note 1- Unless patented splices are used, the bundling of bars in columns is not recommended, as all joints have to be staggered. However, even when patented splices are used the necessary staggering of splices makes assembly difficult and prefabrication cumbersome. 

Note 2- It is recommended to limit the bundle only to two bars or three bars as four bars many times do not tie into a stable bundle. 

Development Length

Ld of each bar of bundled bars shall be that for the individual bar, increased by IO percent for two bars in contact, 20 percent for three bars in contact and 33 percent for four bars in contact. The anchorages of the bars of a bundle can only be straight anchorages. 

Curtailment

Bars in a bundle shall terminate at different points spaced apart by not less than 40 times the bar diameter except for bundles stopping at a support (see Fig. 4.24) 

Splicing

In case of bundled bars, lapped splices of bundled bars shall be made by splicing one bar at a time, such individual splices within a bundle shall be staggered. For bundles of 2, 3 or 4 bars, the staggering distance should be 1.2, 1.3 and 1.4 times the anchorage length of the individual bars respectively.

 

 

Structural Drawing for Detailing

Size of Drawing

• The structural drawing a large project should generally be of one size, convenience both in the drawing office and on the site. The preferred sizes of drawing sheets are given in Table 3.1.
  
• The dimensions recommended for all margins and the divisions of drawing sheets into zones are given in Fig. 3.1 (A to F). 
• The title block is an important feature in a drawing and should be placed at the bottom right-hand corner of the sheet, where it is readily seen when the prints are folded in the prescribed manner. The size of the title block recommended is 185 X 65 mm. 
• Separate sheets should be used for each type of structural member or unit so that a floor slab would be detailed on one sheet, beams on another, and columns on a further sheet, etc. Alternatively, for small jobs each standard size sheet could be used to detail one floor of the structure so that the ground floor slab, beams and columns could be detailed on one sheet and the first floor members on another. 
• Layout -There cannot be a single standard layout for the detailing of reinforced concrete drawings. However, practice to draw th hand corner of the I it is the usual (key) plan in the upper left eet, with the elevations and details below and on to the right side of the plan. Schedules and bending details are placed in the upper right corner of the drawing. Figure 3.2 gives a broad outline of layout recommended. In large projects, the bending schedule can be omitted from individual drawings and a separate bending schedule drawing may be prepared. 

Scale of Drawing 

• Scales shall be so chosen as to bring out the details clearly and to keep the drawings within workable size. The choice of scale will depend at the discretion of the detailer/ designer and no general recommendations can be given in this respect. Some commonly used scales are given below as examples: 

Information to be Shown on Structural Drawings 

• The overall sizes of the concrete members shall include the sizes of any necessary chamfers and fillets at corners. Also, the exact position, shape, size and spacing of the reinforcement within concrete members, as well as the required dimensions oi the concrete cover to the reinforcement shall be given. 
• The position of any holes required in the members for service pipes and details of any pipes or other fixings to be cast-in with the concrete, and also, the position and details of construction joints and special recesses, etc. shall be indicated. 
• When foundations or ground floor slabs are detailed, information regarding the underside conditions shall be shown, such as the use of waterproof paper, the thickness of blinding (the lean layer of concrete), if required. 
• Notes should be used freely on detailed drawings. The most important being the ‘bar marks’ which give information about each, or a series of similar reinforcing bars. The notes should be concise and precise, and shall not be ambiguous. The notes which apply to the whole drawings, such as the specifications of the concrete to be used, size of chamfers and fillets, and concrete cover, etc, can be placed under a general heading at the bottom or side of the drawing. 
• The beams, wall slabs, floor slabs and columns, etc, the main dimensions of the structure, such as the distances between columns, heights between floors, beam and column sizes, and floor and wall thicknesses, etc, as calculated by the design engineer shall also be shown on the drawings. 
• Sections shall be drawn to at least twice the scale of plans or elevations to which they refer, while complicated joints such as may occur at the intersections of columns and beams may be detailed to larger scale, say I : 4. 
• Structural drawings prepared by the designer shall show details of reinforcement and P all other information needed for detailing the reinforcement. The drawings shall also indicate, by separate notes, live loads, concrete strength, quality and grade of steel, number of bars to be lapped and lengths of the laps, and if necessary special instructions regarding erection of formwork, fabrication and placing of steel. 
• It is convenient to detail the reinforcement by units which generally consist of footings, walls, columns, each floor and roof. A separate structural drawing supplemented by bar bending schedule should preferably be made for each unit. For small structures. the entire requirements may be handled as one unit. For a large project a particular unit such as floor may be divided to correspond with the construction schedule. 
• To ensure that all the reinforcement is . properly placed or positioned in a unit, longitudinal section or cross-section should be shown in addition to plan and elevation of the unit on which the bars are shown. 
• The drawing should be complete and clear so as to leave no doubt on any point of construction. Complete and accurate dimensions shall be shown. Clear and adequate details for special and unusual condition shall be given to ensure proper placing of reinforcement. Details of covers and intersections of walls. construction joints, window and door openings, and similar special features should be shown in the relevant drawings along with sketches, if necessary. 
• For clear demarcation of reinforcement bars, those in the near face shall be shown in full lines and those that are placed in the far face shall be shown in dotted lines. 
• All bars, straight or bent requiring hooks bends, shall be properly designated by the designer or a note to this effect included in the drawing. 
• Lengths of laps, points of bend, cut-off points and extension of bars should be specified by the designer. The dimensions L/ 7, L/ 5 and L/4. etc. shown on typical drawings shall not be used unless justified by structural analysis. 
• Wherever possible. all control and construction joints should he indicated on structural drawings and constructional details provided for such joints. 
• Notes and instructions: Any ambiguity and scope for misinterpretation of instructions shall be avoided. All instructions shall be in imperative form, specific, brief and clear. 
• Schedules -The reinforcement details of slabs, beams, columns and many other parts of structures may be effectively shown on working drawings in a tabular form, known as a schedule (see Section 5). 

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Symbols and Abbreviations 

Symbols and abbreviations to be adopted in the drawings for reinforced concrete construction are given in 3.4.1 to 3.5.6. All reinforcement bars used in the structures shall be suitably designated and numbered both on drawing and schedule.

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The symbols, abbreviations and notes shall be used in a manner that will not create any ambiguity. A few examples for representing diameter, spacing, number of bars,etc., are illustrated below: 

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The use of the same type of line for the same purpose considerably enhances the clarity and usefulness of the drawing. The following graphical symbols are suggested:

Additional drawing conventions for use on drawings for reinforcement as suggested in IS0 : 3766-1977 ‘Building and civil engineering drawings-Symbols for concrete reinforcement’ is reproduced in Table 3.2. 

Marks for Parts of Buildings

• Marks are used to designate the different structural members of a structure. Different structural members of a structure shall be marked using symbols, abbreviations and notations indicated in succeeding clauses and in the manner indicated in other clauses. 
• A key framing plan shall be prepared to ai convenient scale and the two axes marked one side with alphabets A, B, C, etc. and the other with numbers (see Fig. 3.3). Normally with rectangular pattern, the same key framing plan may be used for all floors. However, if arrangement of beams vary for different floors a separate key framing plan with grid arrangement and areas may be used for each of the floor. The floors shall be .specified in accordance with the requirements of IS : 2332-1973 ‘Specifications for nomenclature of floors and storeys’ and abbreviations BT and MZ shall be used for basement and mezzanine, respectively, for example: 

• Columns – Columns and foundations shall be specified by grid arrangement giving reference to the floor, for example (ie. 3.3A)

• Beams, slabs and lintels, and tie beams shall be consecutively numbered from left-hand top corner (see Fig. 3.3A). 
• If longitudinal section of the beam is shown, the grid of the column or number of the column supporting the beam is being detailed shall be as indicated as in fig. 3.3B and, if possible, inset on the drawing showing the key framing plan. On the other hand if a beam schedule is included, a table [see Fig. 3.3C] may be prepared and inset on the drawing showing the key framing plan [see Fig. 3.3A]. 
• Beams or slabs that are similar may be given in the same number. 
• Walls – Marking of walls shall be made in the serial order starting from top left corner of plan and proceeding towards the right, followed by subsequent rows in order. Longitudinal walls and cross-walls shall be marked separately (see Fig. 3.4) and identified in the drawing with reference to the serial number of the floor. 

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Bar Bending Schedule (Including Do’S and Dont’s in Detailing)

Bar bending schedules are very important out of detailing and should give the following information:

1. Identification of the structural member(s), 
2. Position of the bars in the structure,
3. The bar mark,
4. The diameter or size of bar,
5. The number of bars of dne type in each structural member,
6. The total number of bars of each type,
7. The total straight length of the bar,
8. The shape and bending dimensions of the bar,
9. The details of bar chairs can also be included, and
10. Remarks, if any. 

Schedules 

The reinforcement of slabs, beams and other parts of structures may be effectively shown on working drawings in a tabular form, known as a schedule. The schedule is a compact summary of the dimensions of the concerned structural part, all the bars complete with the number of pieces, shape and size, lengths and bending details from which fabrication details may be easily worked out. The dimensioning procedure for different bar shapes as shown in Tables 5.1 to 5.7 may be followed.
NOTE – The value of length is the length of straight bar from which the actual shape will be bent or for a straight bar, the length of that bar. This length will be equal-to the sum of individual overall lengths of the straight portions of each shape.

A schedule shall be supplemented with diagrams and sketches wherever necessary. Where bars of different dimensions are used, the exact arrangement of the reinforcement shall be shown by means of clear diagrams. No abbreviation or symbol shall be used in a schedule without proper explanation. 

For small structures detailed on a single sheet, the schedule may be placed in the upper left corner of the drawing. For larger structures requiring more than one drawing, the complete schedule may appear on the last sheet of the details, or if the size of the structure warrants,separate schedules may be prepared for each unit (foundation, abutments, piers, etc) on the drawing covering that specific unit of the structure. 

 Beams, Girders and Joists 

Details of reinforcement for beams, girders and joists are usually shown in schedules. The schedules should show the number, mark and location of member; number, size, position and length of straight bars; number, size, position, bending details and total length of bent bars and stirrups; size, shape and spacing of bar supports; and any other special information necessary for proper fabrication and placement of the reinforcement (see Table 5.8). Care shall be taken not to omit any controlling dimension such as overall length of the bar, height of the bent bar and location of bar with respect to supporting members where the bar is not placed symmetrically. The schedule should also include special notes on bending and any special information, such as the requirements of laps, two layers of steel, etc.

Slabs

The reinforcement for slabs is generally indicated on the plan, with details for the various types of bent bars shown in a schedule (see Table 5.8). The schedule shall be similar to that for bars in beams, except that the number of bars may also be obtained from the plan. Panels exactly alike shall be given an identifying mark or so specified in the schedule. 

In skewed panels, bars shall be fanned to maintain given spacing in the mid span. Additional bars for reinforcing the openings shall be as shown on plan.

In case of welded wire fabric sheet in slab panels, a schedule may also be included in the structural drawing indicating the mesh sizes (length and width) and fitting details for welded wire fabric sheets for different slab panels. A typical schedule is given in Table 5.9. 

Walls 

The reinforcement for walls shall be indicated on the plan, elevation and section with the details for various types of bent bars shown in schedule in a manner similar to that for beams and slabs.

Columns

The reinforcement for columns may be shown in a column schedule. Piles and pile caps should be treated as separate units and separate details or schedule or both may be provided. The main schedule may be supplemented with a smaller schedule for ties and by a small detailed sketch of each bar or type of bar with a table of dimensions. 

Schedule Layout

A typical form of schedule for beams, slabs and columns is shown in Table 5.8 and Table 5.9 shows another typical form schedule for slab using welded wire fabric as reinforcement. Also an example of typical bar bending schedule is given in Table 5.10.

International Standard IS0 : 4066- 1977 ‘Building and civil engineering drawings-Bar scheduling’ establishes a system of scheduling of reinforcing bars comprising the following aspects:

a) the method of Indicating dimensions;

b) a code system of bar shapes;

c) a list of preferred shapes; and

d) the bar schedule form.

This standard is reproduced in Appendix B as a supplement to the information contained in this section.

Do’s and Dont’s for Detailing

• Do’s – General

1. Prepare drawings properly and accurately. lf possible label each bar and show its shape for clarity.
2. Prepare bar-bending schedule. if necessary.
3. Indicate proper cover to reinforcement.
4. Decide location of openings hole and supply adequate details for reinforcement around openings.
5. Commonly available size of bars and spirals shall be used for reinforcement. For a single structural member the number of different sizes of reinforcement bar should be minimum.
6. The grade of reinforcement bars shall be clearly mentioned in the structural drawing.
7. For mild steel plain bars U-type, hooks and for deformed bars L-type hooks may be adopted. Deformed bars need not have hook at their ends.
8. Bars shall have smooth curved edges at the point of bend.
9. In case of bundled bars. lapped splice of bundled bars shall be made by splicing one bar at a time; such individual splices within a bundle shall be staggered.
10. When reinforcement is left exposed for future construction, it should be adequately protected from corrosion and weathering action.
11. Congestion of steel should be avoided at points where members intersect and make certain that all reinforcement shown can be properly placed.
12. Make sure that hooked and bent bars can be placed and have adequate concrete protection.
13. Make sure that bent bars are not so large and unwieldly that they cannot be transported.
14. Indicate all expansion, contraction and construction joints on framing plans and provide details for such joints.
15. Where a section is not on the same sheet as the plan from which it is taken, use a clearly defined system of cross-reference for locations of sections and details.
16. Show enlarged details at corners, intersections of walls. beam and column joint, and at similar special situations. 

• Do’s – Beams and Slabs 

1. Where splices are provided in reinforcing bars, they shall be, as far as possible, away from the sections of maximum stress and shall be staggered.
2. Where the depth of a beam exceeds 750 mm in case of beams without torsion and 450 mm with torsion, side face reinforcement shall be provided.
3. In two-way slab, reinforcement parallel to the short span of the slab shall be placed in the bottom layer at mid-span and ih the top layer at support.
4. All spacing shall be centre-to-centre spacing of bars.
5. Deflection in slabs beams may be reduced by providing compression reinforcement.
6. Only closed stirrups shall be used for transverse reinforcement for members subject to torsion and for members likely to be subjected to reversal of stress.
7. At beam-column intersections ensure that the main beam bars avoid the main column bars.
8. At beam-beam intersections, main reinforcement may be so arranged that layers in mutually perpendicular beams are at different levels.
9. To accommodate bottom bars, it is good practice to make secondary beams shallower than main beams, at least by 50 mm.
10. If it is required the beam cages may be pre- assembled with splice bars.

• Do’s – Columns 

1.  A reinforced column shall have at least six bars of longitudinal reinforcement for using in transverse helical reinforcement. 
2. Spacing of longitudinal bars in column shall be along the periphery of the column. as far as practicable.
3. Column bars of diameters larger than 36 mm in compression can be spliced with dowels at the footing with bars of smaller sizes and of necessary area.
4. A dowel shall extend into a column, a distance equal to the development length of the column bar and into footing a distance equal to development length of the dowel.
5. Keep outer dimensions of column constant, as far as possible, for re-use of forms.
6. Preferably avoid use of two grades of vertical bars in the same element.

• Dont’s-General

1. Reinforcement shall not extend across an expansion joint and the break between the sections shall be complete. 
2. Flexural reinforcement, preferably, shall not be terminated in a tension zone. If such case is essential, the condition as given in Section 4 shall be satisfied.
3. Lap splices shall not be used for bars larger than 36 mm diameter except where welded.
4. Bars larger than 36 mm diameter shall not be bundled.
5. Where dowels are provided their diameter shall not exceed the diameter of the column bars by more than 3 mm.
6. Where bent bars are provided, their contribution towards shear resistance shall not be more than half that of the total shear reinforcement.
7. Different types of reinforcing bars such as deformed bars and plain bars and various grades like 415 N/sq.mm and 215 N/sq.mm should not be used side by side as this practice would lead to confusion at site. However, secondary reinforcement such as links ties and stirrups may be of mild steel throughout, even though the main steel may be of high strength deformed bars.
8. Under no circumstances should the bending of bars at welds be permitted.

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Detailing Functions

General

In preparing drawings and bending schedules, the following factors shall be kept in view:

a) The engineer’s design and the design requirements;

b) The cutting and bending of the reinforcement;

c) The placing and wiring in position of reinforcement; 

d) The maintaining of the position of reinforcement;

e) The pre-assembly of cages;

f) Concreting; 

g) The accommodation of other trades and services;

h) The measurement of quantities; and 

j) Economy in the use of steel. 

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a) Design

The following requirements of the designer shall be borne in mind: 

1) The quantity, location and cover of steel reinforcement should be simply, correctly and clearly shown.

2) The placing drawings and bending schedules should be adequately cross-referenced, easily read and capable of easy checking in the drawing office and on site.

3) It should be possible to locate a detail readily, should a doubt arise. 

4) One detailer should be able to take over from another with a minimum of delay and direction. 

5) Detailing should be done in such a way that secondary stresses caused by support conditions, shrinkage, temperature variations, bursting effects of laps and splices, and stress concentrations arising from hooks and bends are counteracted.

b) Cutting and Bending

Prepare bending schedules on standard size sheets small enough to facilitate handling by clerical, fabrication and placing personnel.

Standardize cutting lengths and ensure that bending details are simple and easy to read. So compile the schedules that delivery of the required reinforcement for each component can be effected without the need for abstracting from schedules. The system of bar-referencing should be coherent and systematic, and should lend itself to easy identification and to use in computer systems, if necessary. 

c) Placing and Wiring in Position 

Ensure that drawings arc simple, pictorially clear, and adequately detailed to enable the fixer to place bars exactly where required. Avoid crowding drawings with information by detailing by components and also if necessary by preparing separate details for bottom and top steel in slabs. Ensure that reinforcing steel that connects elements to be cast at different times is so detailed that it is included with the portion to be cast first, for example, splice bars for columns, continuity reinforcing for beams and slabs to be cast in portions. If the order of casting is not clear, detail splices in one of the sections with suitable cross-references. Where the complexity of the detail is such that an, out of the ordinary sequence is required to place the reinforcement, ensure that such sequence is shown on the detail.

d) Maintaining Position of Reinforcement 

Reinforcement that has been placed and wired in position should not be displaced before or during the concreting operation. Ensure that bar supports and cover blocks are so scheduled or specified as to maintain correct bottom and side cover and that high chairs and stools are detailed to support upper reinforcement mats at the correct level.

e) Pre-assembly of Cages and Mats

Where required, so detail the reinforcement to components such as columns, foundations, beams, and walls that it can be conveniently pre-assembled before being placed in position. Ensure that assembled units are sturdy enough to stand up to handling and erection, and that they are not so heavy that they cannot be lifted by the men or equipment available for the work. 

f) Concreting

Ensure that the reinforcement can be spread as to follow placing and efficient consolidation of the concrete.

g) Other Trades and Services

Take note of the positions of down pipes (especially inlets and outlets), sleeves, pipes, and electrical conduits, whether shown on the structural layout or not. To avoid site difficulties, show them on the reinforcement details where necessary.

h) Measurement of Quantities

It is important that the quantity surveyor and the contractor should be able to compute the mass of steel used at any stage in a contract. Bending schedules prepared as recommended in 2.3 will assist in meeting this requirement. Ensure that placing drawings and bending schedules are adequately cross-referenced and that all revisions are suitably recorded. If. in the case of a revision, there is any possibility of doubt, prepare separate schedules showing only the revision, with adequate cross-referencing. 

i) Economy in Use of Steel 

The type of steel used is generally specified by the designer but
bear in mind that up to one-third of the mass of steel can be saved by using high tensile steel instead of mild steel. The saving can be considerable as the difference of cost between the rates for mild steel and high tensile steel placed in position is relatively small. Furthermore, as the rates for small diameters are higher than those for large diameters, it is desirable to use the largest available size of bar within the design requirements. Larger bars also. produce Stiffer cages and are not easily displaced.

 

Steel for Reinforcement

Reinforcing bars/ wires for concrete reinforcement shall be any of the following conforming to accepted standards: 

a) Mild steel and medium tensile steel bars

[IS : 432 (Part I)-1982 Specification for mild steel and medium tensile steel bars and hard-drawn steel wire for concrete reinforcement : Part I Mild steel and medium tensile steel bars (third revision)]. 

b) High strength deformed steel bars/ wires

[IS : 1786-1985 Specification for high strength deformed steel bars and wires for concrete reinforcement (third revision)]. 

c) Hard-drawn steel wire fabric

[IS : 1566-1982 Specification for hard-drawn steel wire fabric for concrete reinforcement (second revision)]. 

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Mild steel and medium tensile steel bars

Grades of Steel

Mild steel bars shall be supplied in the following two grades:

a) mild steel bars, Grade I; and

b) mild steel bars, Grade II.

 

Tolerance

1) Bars in straight lengths 

a) The tolerance on diameter shall be as follows: 

 

b) The permissible ovality measured as the difference between the maximum and minimum diameter shall be 75 percent of the tolerance (k) specified on diameter. 

c) The tolerance on weight per m length shall be as follows: 

2) Coiled bars

a) The tolerance on diameter shall be +/- O.5 mm for diameters up to and including 12 mm.

b) The difference between the maximum and minimum diameter at any cross-section shall not exceed 0.65 mm. 

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High strength deformed steel bars/ wires

Grades of Steel

Deformed steel bars/ wires for use as reinforcement in concrete shall be in the following three grades:

a) Fe415,

b) Fe500, and

c) Fe550. 

Tolerance (High Strength Deformed Steel Bars)

Cutting tolerance on length

The cutting tolerances on length shall be as specified below:

a) When the specified length is not stated to be either a maximum or a minimum +75 mm or -25 mm

b) When the minimum length is specified+50 mm or – 0 mm 

Mass

For the purpose of checking the nominal mass, the density of steel shall be taken as 0.785 kg/sq.cm of the cross-sectional area per metre run.

Tolerances on nominal mass shall be as follows: 

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Hard-drawn Steel Wire Fabric 

General

Hard-drawn steel wire fabric consists of longitudinal and transverse wires (at right angles to one another) joined by resistance spot welding. Fabrication of wire fabric by welding has the quality of factory fabrication and reduces cost of labor and fabrication in the field. 

Types

Hard-drawn steel wire fabric shall be made in the following two types:

a) square mesh, and

b) oblong mesh.

1. The diameter of wires in the square mesh varies from 3 to 10 mm; the diameter being same in both longitudinal and transverse directions.
2. In this case both longitudinal and transverse bars may serve as main reinforcement.
3. The diameter of wire in the oblong mesh varies from 5 to 8 mm in the longitudinal direction and 4.2 to 6 mm in the transverse direction.
4. The wires in the direction of larger diameter can serve as main reinforcement and the wires in the cross direction can serve as distribution steel. 
5. The maximum width of wire fabric in rolls is 3.5 m; the length of this type of fabric is limited by the weight of rolls which may range from 100 to 500 kg.
6. The maximum width of fabric in the form of sheets is 2.5 m and the maximum length is 9.0 m. The dimension of width is to be taken as centre-to-centre distance between outside longitudinal wires.
7. The width of wires fabric in rolls or sheets shall be such as to fit in with the modular size of IO cm module and length in suitable intervals.

Tolerances

Tolerance on size of mesh

a) The number of spaces between the external wires in a sheet or roll shall be determined by the nominal pitch.

b) The centre-to-centre distance between two adjacent wires shall not vary by more than 7.5 percent from the nominal pitch.

c) The maximum variation in the size of any mesh shall be not more than 5 percent over or under the specified size, and the average mesh size shall be such that the total number of meshes contained in a sheet or roll is not less than that determined by the nominal pitch.

Tolerance on size of sheet

a) When fabric is required to be cut to specified dimensions, the tolerance shall be as follows: 

b) Tolerance on weight of fabric – The tolerance on the weight of fabric shall be as follows: 

 

Windows and Doors Framing

• Firstly, all the stone material is cut according to the sizes required

• A layer of Cement Paste is placed on the surface where Stone is to be placed.
• Then a layer of White Cement is applied on the stone.
•  The stone is fixed on the desired place and leveled as required with the help of Spirit Level as shown in the image above.

Note: The thickness of the cement layer should not be more than half inch.

Araldite HV 953 IN and Araldite AW 106

Epoxy resin in very small quantity is applied on the surface of the stone where both the stones are placed one above the other.

• Then another strip of stone which has smaller width is placed above the stone having larger width.

Note: There are two methods of fixing Stone frames:

1. The stone having larger width will come inside and the stone having smaller width will come outside as shown in the figure.
2. The stone having smaller width will come inside and the stone having larger width will come  outside.

99% times option 2 is used as this method does not allow the water to come inside.

Here option 1 is selected as the window will be fully packed with glass, so there will be no chances of water to enter inside.

Gap between the stone joints is left to fill it with glass strip.

Note: If a stone of more than 2 m span is used on the top, screws should be used to provide anchorage.

Test on Blanket Material

Tests on Bitumen

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Tests on Soil

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Tests on Hardened Concrete

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Tests on Fresh Concrete

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Tests on Aggregates

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Tests on Cement

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Quantities of Steel & R.C.C. Elements

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Unit Rates

Preparation of Unit rates for finished items of works

Lead Statement & Data Sheet

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Quantity of Materials

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Basement Steps

Estimation of basement steps (one way)

Pictured Roof

Estimate the Quantities of the pictured roof shown in figure

Compound Wall

From the given figure below calculate the details estimate for the Compound Wall

R.C.C. Stair Case

Calculate the quantities of items of the stair case of the figure shown in below.

 

Problems on Unit Base Method

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Problem on Cubical content Method

Problems on Plinth Area Method

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Introduction to Estimation

NEED FOR ESTIMATION AND COSTING

1. Estimate give an idea of the cost of the work and hence its feasibility can be determined i..e whether the project could be taken up with in the funds available or not.

2. Estimate gives an idea of time required for the completion of the work.

3. Estimate is required to invite the tenders and Quotations and to arrange contract.

4. Estimate is also required to control the expenditure during the execution of work.

5. Estimate decides whether the proposed plan matches the funds available or not. 

PROCEDURE OF ESTIMATING OR METHODS OF ESTIMATING

Estimating involves the following operations:

1. Preparing detailed Estimate.

2. Calculating the rate of each unit of work

3. Preparing abstract of estimate

DATA REQUIRED TO PREPARE AN ESTIMATE

1. Drawings i.e.plans, elevations, sections etc.

If the drawings are not clear and without complete dimensions the preparation of estimation become very difficult. So, It is very essential before preparing an estimate.

2. Specifications.

a) General Specifications: This gives the nature, quality, class and work and materials in general terms to be used in various parts of wok. It helps no form a general idea of building.

b) Detailed Specifications: These gives the detailed description of the various items of work laying down the Quantities and qualities of materials, their proportions, the method of preparation workmanship and execution of work.

3. Rates

For preparing the estimate the unit rates of each item of work are required.

a) For arriving at the unit rates of each item.

b) The rates of various materials to be used in the construction.

c) The cost of transport materials.

d) The wages of labour, skilled or unskilled of masons, carpenters, Mazdoor, etc.

COMPLETE ESTIMATE

Most of people think that the estimate of a structure includes cost of land, cost of materials and labour, But many other direct and indirect costs included and is shown below:

LUMP SUM

While preparing an estimate, it is not possible to workout in detail in case of petty items. Items other than civil engineering such items are called lump sum items or simply L.S.Items. The following are some of L.S. Items in the estimate.

1. Water supply and sanitary arrangements.

2. Electrical installations like meter, motor, etc.,

3. Architectural features.

4. Contingencies and unforeseen items. In General, certain percentage on the cost of estimation is allotted for the above L.S.Items Even if sub estimates prepared or at the end of execution of work, the actual cost should not exceed the L.S.amounts provided in the main estimate.

WORK CHARGED ESTABLISHMENT

During the construction of a project considerable number of skilled supervisors, work assistance, watchmen etc., are employed on temporary basis. The salaries of these persons are drawn from the L.S. amount allotted towards the work charged establishment. that is, establishment which is charged directly to work. an L.S.amount of 1½ to 2% of the estimated cost is provided towards the work charged establishment.

TYPES OF ESTIMATES

DETAILED ESTIMATE:

The preparation of detailed estimate consists of working out quantities of various items of work and then determine the cost of each item.

This is prepared in two stages.

i) Details of measurements and calculation of quantities: The complete work is divided into various items of work such as earth work concreting, brick work, R.C.C. Plastering etc., The details of measurements are taken from drawings and entered in respective columns of prescribed proforma. the quantities are calculated by multiplying the values that are in numbers column to Depth column as shown below:

Details of measurements form

ii) Abstract of Estimated Cost : The cost of each item of work is worked out from the quantities that already computed in the details measurement form at workable rate. But the total cost is worked out in the prescribed form is known as abstract of estimated form. 4% of estimated Cost is allowed for Petty Supervision, contingencies and Unforeseen items.

Abstract of estimate form

The detailed estimate should accompanied with

i) Report

ii) Specification

iii) Drawings (plans, elevation, sections)

iv) Design charts and calculations v) Standard schedule of rates.

Factors to be considered While Preparing Detailed Estimate

i) Quantity and transportation of materials: For bigger project, the requirement of materials is more. such bulk volume of materials will be purchased and transported definitely at cheaper rate.

ii) Location of site: The site of work is selected, such that it should reduce damage or in transit during loading, unloading, stocking of materials.

iii) Local labour charges: The skill, suitability and wages of local labourers are considered while preparing the detailed estimate

Data

The process of working out the cost or rate per unit of each item is called as Data. In preparation of Data, the rates of materials and labour are obtained from current standard scheduled of rates and while the quantities of materials and labour required for one unit of item are taken from Standard Data Book (S.D.B)

Fixing of Rate per Unit of an Item

The rate per unit of an item includes the following:

i) Quantity of materials & cost: The requirement of mateials are taken strictly in accordance with standard data book(S.D.B). The cost of these includes first cost, freight, insurance and transportation charges.

ii) Cost of labour: The exact number of labourers required for unit of work and the multiplied by the wages/ day to get of labour for unit item work.

iii) Cost of equipment (T&P): Some works need special type of equipment, tools and plant. In such case, an amount of 1 to 2% of estimated cost is provided.

iv) Overhead charges: To meet expenses of office rent, depreciation of equipment salaries of staff postage, lighting an amount of 4% of estimate cost is allocated.

METHODS OF PREPARATION OF APPROXIMATE ESTIMATE:

Preliminary or approximate estimate is required for studies of various aspects of work of project and for its administrative approval. It can decide, in case of commercial projects, whether the net income earned justifies the amount invested or not. The approximate estimate is prepared from the practical knowledge and cost of similar works. The estimate is accompanied by a report duly explaining necessity and utility of the project and with a site or layout plan. A percentage 5 to 10% is allowed for contingencies.

The following are the methods used for preparation of approximate estimates.

a) Plinth area method

The cost of construction is determined by multiplying plinth area with plinth area rate. The area is obtained by multiplying length and breadth (outer dimensions of building). In fixing the plinth area rate, careful observation and necessary enquiries are made in respect of quality and quantity aspect of materials and labor, type of foundation, height of building, roof, wood work, fixtures, number of storeys etc.

As per IS 3861-1966, the following areas include while calculating the plinth area of building:

a) Area of walls at floor level.

b) Internal shafts of sanitary installations not exceeding 2.0 sq.m, lifts, air conditioning ducts etc.

c) Area of barsati at terrace level: Barsati means any covered space open on one side constructed on one side constructed on terraced roof which is used as shelter during rainy season.

d) Porches of non cantilever type.

Areas which are not to include

a) Area of lofts.

b) Unenclosed balconies.

c) Architectural bands, cornices etc.

d) Domes, towers projecting above terrace level.

e) Box louvers and vertical sun breakers.

b) Cubical contents methods

This method is generally used for multi-storeyed buildings. It is more accurate than the other two methods viz., plinth area method and unit base method. The cost of a structure is calculated approximately as the total cubical contents (Volume of buildings) multiplied by Local Cubic Rate. The volume of building is obtained by Length x breadth x depth or height. The length and breadth are measured out to out of walls excluding the plinth off set. The cost of string course, cornice, carbelling etc., is neglected. The cost of building= volume of buildings x rate/ unit volume.

c) Unit base method 

According to this method the cost of structure is determined by multiplying the total number of units with unit rate of each item. In case schools and colleges, the unit considered to be as ‘one student’ and in case of hospital, the unit is ‘one bed’. the unit rate is calculated by dividing the actual expenditure incurred or cost of similar building in the nearby locality by the number of units.

 

 

Units of Materials Measurement

Painting

Painting two coats over a coat of priming for 10 sq.m area.

Water Bound Distemper

Providing water bound distemper of approved brand and shade in two coats [inclusive of priming coat of whitewash], scaffolding, etc. complete

Mangalore Tiled Roofing

Providing and fixing mangalore tiled roofing with class A-A tiles with horizontal teak wood battens, iron work and oiling the battens, etc. complete.

Flush Grooved Pointing

Providing flush grooved pointing with cement mortar (1:3) for brickwork including scaffolding and curing, etc. complete.

Internal Plastering with Neeru Finish

Providing 12 mm thick plastering in cement mortar (1:4) with neeru finish to internal  surfaces including scaffolding, curing, etc. complete.

 

Internal Plastering without Neeru Finish

Providing 12 mm thick internal plastering in cement mortar (1:4) without neeru finish to concrete or brick surfaces including scaffolding and curing, etc. complete.

Vitrified Tiles

Providing and laying vitrified tiles, over 20 mm thick cement mortar (1:6) for 10 cum. area.

Cement Concrete Flooring

Providing and laying 2.50 cm thick cement concrete flooring using M15 (1:2:4) concrete for 10 sq.m area.

Mild Steel Reinforcement

Providing and fixing in position mild steel reinforcement including bending, binding, hooking, wastage, laps, etc, complete.

R.C.C. work including Steel

Providing cast in situ R.C.C. work in beams, slabs, etc. using M15 concrete (1:2:4) excluding steel but including centering, shuttering, bending and binding.

R.C.C. work excluding Steel

Providing cast in situ R.C.C. work in beams, slabs, etc. using M15 concrete (1:2:4) excluding steel but including centering, shuttering, bending and binding.

1st Class Brickwork

Providing 1st class brickwork in superstructure in cement mortar (1:6) with I.S. size bricks 19 cm x 9 cm x 9 cm including raking of joints, watering, scaffolding, etc. complete.

Coursed Rubble Masonry

Providing and laying coursed rubble masonry in superstructure in cement mortar (1:6) including watering, scaffolding, etc. complete.

P.C.C in Foundation

Providing and laying P.C.C. (1:4:8) in foundations including balling out of water manually, formwork, compaction, curing, etc. complete.

Uncoursed Rubble Masonry

Providing and laying uncoursed (random) rubble masonry in cement mortar (1:6) including watering, scaffolding, etc. complete.

Excavation for Foundation

Excavation for foundation in earthen soil including removal of excavated material to normal lead of 50 m and lift of 1.5 m, shoring, strutting, preparing the bed for foundation, dewatering and back filling, etc. complete.

Unit 1 cum.

Load of 1 tonne

Estimation of R.C.C. Beam

Estimation of R.C.C. Beam

Estimate of R.C.C. Column

Measurement Sheet

Abstract Sheet

Mangalore Tiled Roof

To calculate the number of Mangalore tiles and battens required to cover an area of 10 sq.m

Size of Mangalore tiles = 41 cm x 24 cm

and it can cover an area of 32 cm x 21 cm

Therefore, Area covered by one tile with overlap = 32 cm x 21 cm = 0.32 sq.m x 0.21 sq.m

= 0.672 sq.m

Therefore, Total number of tiles required = (Area to be covered / Area of one tile with overlap)

= 10 / 0.0672 = 148.81 = 149 Nos.

Length of the ridge tile = 40 cm

The size of teak wood battens is equal to 5 cm x 2.5 cm and are usually fixed at 30 cm c/c

Therefore, the length of the battens required = 36 m

Floor Finishes

Item: Plain cement tiles 20 mm thick over cement mortar (1:6) screeding, including cement float, etc.

The quantities of plain cement tiles, cement and sand required for flooring 10 sq.m area will be determined as follows:

• Plain cement tiles including 5% wastage = 10.5 sq.m
• Quantity of mortar for screeding, assuming 20 mm thickness

= 10 (sq.m) x 2 / 1000 (m) = 0.2 cum.

Quantity of Cement required for (1:6) proportion = 0.26 / (1+6) = 0.037 cum.

= 0.037 x 30 = 1.11 bags of cement

and Quantity of cement required for float, assuming 1.5 mm thickness = 10 x 0.0015

=0.015 cum.

=0.015 x 30 = 0.45 bags of cement

Therefore, Total quantity of cement required = 1.11 + 0.45 = 1.56 bags

and, Quantity of sand required = [0.26/(1+6)] x 6 = 0.222 cum. = 0.25 cum.

Pointing

The volume of dry mortar required for pointing depends upon the type of surface i.e. either brick work or masonry work.

For pointing ( which may be flush, struck or keyed) to the brick work, the dry volume of mortar , including wastage, required for 10 sq.m area is about 0.036 cum. and for random rubble masonry it is 0.076 cum.

Thus knowing the proportion of the mix of the mortar as 1:3, the quantity of cement and sand can be found out as follows:

• For pointing to brick work

Volume of cement required = 0.036 / (1+4) = 0.009 cum.

= 0.009 x 30 = 0.270 bags

and, Volume of sand required = [0.036 / (1+3)] x 3 = 0.027 cum.

• For pointing to random or coursed rubble masonry, the volume of dry mortar required = 0.076 cum.

Therefore, For pointing in cement mortar (1:3) proportion,

Quantity of cement required = 0.076 / (1+3) = 0.019 cum.

= 0.019 x 30 = 0.57 bags = 0.60 bags of cement

and, Quantity of mortar required = [0.076 / (1+3)] x 3 = 0.057 cum.

Plastering

To determine the quantity of cement (or lime) and sand, required for plastering unit square metre of the area of various thickness is to work out the volume of mortar required per sq.m of plaster by multiplying the area to be plastered by its thickness.

In order to allow extra mortar for raked out joints, cavities, uneven surfaces, etc. the above worked out quantity is to be increased approximately by 30%.

Further to convert the wet volume of mortar into its corresponding dry volume, it should be increased by about 30%.

Then the quantities of cement and sand required can be determined by dividing the total dry volume of mortar by the sum of the numerical figures of proportion or mix of the mortar and multiplying it by the individual numerical figures.

e.g. To determine the quantities of cement and sand for 12 mm thick plaster in cement mortar (1:4), the procedure would be as follows:

Considering the area to be plastered as 10 sq.m, with a thickness of 12 mm, the quantity of wet mortar required = 10 (sq.m) x 1.2 / 100 (m) = 0.12 cum.

Therefore, Adding 30% extra for filling joints, and uneven surface, etc., quantity of wet mortar required = 0.12 + (0.3 x 0.12) = 0.156 cum.

Therefore,  Quantity of dry mortar required = 0.156 + (0.3 x 0.156) = 0.156 + 0.0468

= 0.2028 cum.

Further, allowing for wastage, etc.

The total quantity of dry mortar required = 0.203 cum.

Therefore, Quantity of cement required = 0.203 / (1+4) = 0.041 cum.

= 0.042 x 30 = 1.23 bags

and Quantity of sand required = [0.203 / (1+4)] x 4 = 0.162 cum.

Approximate method

The approximate method of determining the volume of dry mortar required is to multiply the quantity of wet mortar required by a factor 1.8

i.e. Volume of wet mortar required = 0.12 cum.

Therefore, Volume of dry mortar required = 0.12 x 1.8 = 0.216 cum.

Therefore, Quantity of cement required = 0.216 / (1+4) = 0.043 cum.

= 0.043 x 30 = 1.29 = 1.30 bags

and, Quantity of sand required = [0.216 / (1+4)] x 4 = 0.0173  cum. which is same as determined above.

Neeru finish coat of 1.5 mm thickness.

If the inside face is to be plastered further with a Neeru finish of 1.5 mm thickness then the quantity of Neeru required for 10 sq.m surface

= 10 (sq.m) x 1.5 / 1000 (m)

= 0.015 cum.

i.e. 0.015 x 30 = 0.45 bags = 0.5 bags of Neeru which is available as ‘Sagol’ or ‘Sunala’ as brand name in the market.

 

10 cm Thick Brick Work in partition Walls in Cement Mortar (1:4)

In order to calculate  the quantities of cement and sand required for 10 cm thick brick partition wall, with I.S. size (i.e. modular) bricks, the procedure would be as follows.

Considering 10 sq.m area of the brick work to be constructed with 10 cm thick wall.

The quantity of brick work in partition = 10 x (10/100) = 1 cum.

Therefore, Number of bricks required (considering the thickness of joints on 10 cm)

= 100/(0.20 x 0.1 x 0.1)

=500

Adding 5% extra for wastage = 25

Therefore, Total number of bricks = 525

Therefore, Quantity of mortar required = (10 x 0.1) – 500(0.19 x 0.9 x 0.9) = 1 – 0.77 = 0.23

Adding 10% extra for frog, bonding, wastage, etc. = 0.023

Therefore, Wet volume of mortar required = 0.253 cum.

Therefore, Dry volume required = 1.25 x 0.253 = 0.316 cum. = 0.30 cum.

i.e. for 10 sq.m area of brick work thickness 10 cm, the quantity of dry mortar required = 0.3 cum.

Further, knowing the proportion of mix, the quantities of cement and sand can be found out by dividing the total quantity of dry volume of mortar by the sum of the numerical figures of the proportion or mix of the mortar and then multiplying it by the individual numerals.

Reinforcement for Reinforced Cement Concrete

• It is usual practice to express the steel required for reinforced cement concrete as percentage of volume of concrete e.g. 1% steel in R.C.C. slab indicates that the quantity of steel required will be equal to 1% of the volume of concrete i.e. for every one square metre sectional area of the slab cut, there will be 0.01 sq.m of steel bar utilized.
• As the steel weighs 7850 kg per cubic metre, the 1% steel reinforcement means there will be 78 kg of steel per  cubic metre of volume of concrete.
• The values of usual percentage of steel assumed for various items will be as shown below:
• The quintal of binding wire for reinforced steel is usually assumed as 1 to 1.3 kg per quintal of steel reinforcement.
• Due allowance is to be made for wastage of steel which is 5 to 10%

Main Brick Work in Superstructure

• In order to calculate the quantities of materials required for brick work in cement mortar, it is necessary to decide the size of the bricks to be used in the masonry.
• The size of the conventional or traditional bricks vary from 8 3/4″ x 3 3/16″ x 2 5/8″ (i.e. 22.23 cm x 10.64 cm x 6.67 cm) to 9″ x 4 1/2″ x 3″ (i.e. 22.86 cm x 11.43 cm x 7.62 cm)
• The new I.S. size brick i.e. modular brick is actual 19 cm x 9 cm x 9 cm with a frog of 10 cm x 4 cm x 1 cm size.
• Normally, the mortar joint is taken as 1 cm throughout, therefore, the normal size of brick will be 20 cm x 10 cm x 10 cm.

Therefore, Volume of one I.S. size brick, with thickness of joint as 1 cm = 0.20 x 0.1 x 0.1 = 0.002 cum.

Therefore, For 1 cum. of brick work, the total number of I.S. size (i.e. modular) bricks required = 1 cum. /0.002 = 500 Nos.

Therefore, Adding 5% towards wastage = 25

Therefore, Total number of I.S. bricks required = 525 Nos.

Now,

Quantity or volume of wet mortar required = (Total volume of brick work) – (Volume occupied by 500 bricks of 19 cm x 9 cm x 9 cm size)

= (1 – 500 x 0.19 x 0.09 x 0.09) cum

= 1 – 0.7695

=0.2305 cum.

In order to allow for mortar for filling the frog, bonding and wastage during its use, 10% is to be added.

Therefore, Volume of wet mortar required = 0.2305 + 0.10 x 0.2305

= 0.235 cum.

Therefore, Dry volume of mortar required = 1.25 x 0.235

= 0.316 = 0.30

i.e. Approximately for 1 cum. of brick work, 30% of the dry mortar will be required.

Calculations of materials for 1 cum. of brick work in C.M. (1:6) with traditional size bricks 9″ x 4.375″ x 2.75″ (i.e. 22.86 cm x 11.11 cm x 6.985 cm)

Assuming thickness of joint as 1 cm throughout, the nominal size of traditional bricks = 23.86 cm x 12.11 cm x 7.985 cm

Therefore, Volume of one traditional size brick with 1 cm as thickness of joint = (0.2386 x 0.1211 x 0.07985) cum. = 0.002307 cum.

Number of traditional bricks required for 1 cum. of brickwork = 1/0.002307

= 433 Nos.

Add 5% towards wastage = 22

Therefore, Total number of traditional bricks required = 455 Nos.

Now, Value of wet mortar required = 1 – 433 x (0.2286 x 0.1111 x 0.06985)

= 1 – 0.77

= 0.23 cum. which is practically same as derived above

Therefore, Adding 10% extra for wastage = 0.023 cum.

Therefore, Wet volume of mortar required = 0.253 cum.

Therefore, Dry volume required = 1.25 (wet volume)

= 1.25 x 0.253

=0.316 cum. = 0.30 cum.

i.e. approximately 30% of dry volume of mortar is required for constructing 1 cum. of brick work. Further, knowing the proportion of cement mortar the quantities of cement (in bags) and sand can be worked out as usual.

e.g. knowing the proportion of the cement mortar, the quantities of cement and sand required can be  determined as follows.

For cement mortar (1:6) proportion,

Quantity of cement required = (Dry volume of mortar)/(1+6) = (0.316/7)

= 0.045 cum. = 0.045 x 30 = 1.35 bags of cement

and, Quantity of sand required = (0.316/7) x 6 = 0.2708 cum. = 0.27 cum.

Approximate method:

The above quantities can be determined by an approximate method as follows:

For 1 cum. of brick work divide 0.3 by the sum of the proportion of the material to obtain the quantity of cement in cubic metre

i.e. Quantity of cement required = (0.3)/(1+6) = 0.3/7 = 0.043 cum.

But as certain amount of cement will be required to fill the voids in the sand, add 0.002 cubic metre extra.

Therefore, Quantity of cement required = 0.043 + 0.002 = 0.045 cum. which is same as above

Therefore, Number of cement bags required = 0.045 x 30 = 11.35 bag

and, Quantity of sand required = 0.045 x 6 = 0.27 cum.

Plain Cement Concrete (P.C.C)

1. The materials required for preparation of cement concrete are cement, sand (i.e. fine aggregates) and ballast (i.e. coarse aggregates) which are to be mixed in the predetermined proportion.
2. The voids in the coarse aggregates are filled by fine aggregates and that in the fine aggregates are filled with by cement paste (i.e. cement and water).
3. Thus the wet volume of the cement concrete (i.e. when water is added to the dry cement concrete mix) will always be less than its corresponding dry volume (i.e. sum of total volume of each ingredient added together).
4. It has been observed that in order to prepare 1 cum. of wet cement concrete, the corresponding dry volume required is about 1.52 cum.
5. Knowing the mix of the cement concrete (i.e. 1:4:8 or 1:3:6 or 1:2:4 etc.) the ingredient materials required can be determined as follows:

To determine the materials required for 1 cum. of (wet) concrete of 1:4:8 proportion, the dry volume of concrete required will be 1.52 cum. (which shrinks to 1 cum. after adding of water to it)

As 1 cum. of cement is equivalent to 30 bags of cement (each bag weighing 50 kg)

The quantity of cement required = 0.117 x 30 = 3.51 bags = 3.50 bags.

The following table gives the quantities of materials required for cement concrete of various proportion (i.e. mix) by volume.

Requirement of Cement in Bags for Various Common Items of Construction

Item of Work

• Plain Cement Concrete

• Reinforced Cement Concrete

• Stone Masonry

• Brick Masonry

• Damp Proof Course

• Plastering 

• Pointing Work

• Flooring

 

Increase in Rates for Additional Floors

Note: For items of construction of superstructure of a building, the prices (i.e. rates) are to be increased for subsequent floor as more effort is required for transporting material to subsequent floors:The above increase in price shall be over the ground floor rates only.

Labor Requirements for Different Items of Works

The Report of Productivity project of National Building Organization (N.B.O.) New Delhi specifies the labor requirements of various categories for different items of work as follows:

• Excavation and Earth Work

• Concreting

• Placing the concrete in position

• Form work for concrete

• Brick work

• Stone masonry

• Wood work and joinery

• Flooring

• Plastering and pointing

• White washing, Color washing, Distempering

 

 

Detailing of Beam & Slab

PROBLEM No. 1

Draw the Longitudinal section and two cross sections one near the support and other near the mid span  of a R.C.C.  continuous beam with the following data:

Clear span of beams = 3 m each

Width of beam = 200 mm

Overall depth of beam = 300 mm

Width in intermediate supports = 200 mm

Main reinforcement = 4 Nos -12 mm diameter bars with 2 bars bent up

Anchor/hanger bars= 2-10 mm diameter

Stirrups = 6 mm diameter @ 300 mm c/c.

Materials : HYSD bars  and  M20 grade concrete

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PROBLEM No. 2

A rectangular beam of cross section 300 x 450 mm is supported on 4 columns which are equally spaced at 3 m c/c. The columns are of 300 mm x 300 mm in section. The reinforcement consists of 4 bars of a 6 mm diameter (+ve reinforcement) at mid span and 4 bars of 16 mm diameter at all supports (-ve reinforcement). Anchor bars consists of a 2-16 mm diameter. Stirrups are of 8 mm diameter 2 legged vertical at 200 c/c throughout. Grade of concrete is M20 and type of steel is Fe 415.

Draw longitudinal section and important cross sections.

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PROBLEM No. 3

Draw to scale of 1:20 the Longitudinal section and two cross-section of a cantilever beam projecting 3.2 from a support using following data

Clear span  =3.2m

Overall depth at free end  = 150 mm

Overall depth at fixed end  = 450 mm

Width of cantilever beam  = 300 mm

Main steel = 4-28 mm dia with two bars curtailed at 1.5 m from support

Anchor bars  = 2 Nos. 16 mm dia

Nominal stirrups   = 6mm dia at 40 mm c/c

Bearing at fixed end   = 300 mm

Use M20 concrete and Fe 415 steel

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PROBLEM No. 4

A cantilever beam with 3.2 m length is resting over a masonry wall and supporting a slab over it. Draw to a suitable scale Longitudinal section, two cross-sections and sectional plan with the following data:

Size of beam = 300 mm x 350 mm at free end and 300 mm x 450 mm at fixed end and in the wall up to a length of 4.8 m

Main steel: 4 nos. of 25 mm dia bars, two bars curtailed at 1.2 m from free end

Hanger bars: 2 nos. 16 mm.

Stirrups: 6 mm dia 2 legged stirrups @ 200 mm c/c the support length and @100 mm c/c from fixed end up to length of 1 m @ 150 mm c/c up to curtailed bars and remaining @ 200 c/c.

Use M20 concrete and Fe 415 steel

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PROBLEM No. 5

A beam has following data

Clear span = 4m

Support width = 300mm

Size of web = 350 x 400

Size of flange = 1200 x 120mm

Main reinforcement  in two layers :  3-20 tor + 3-16 tor and to be curtailed at a distance 400 mm from inner face of support

Hanger bars: 3- 20 tor

Stirrups: 2L-8 tor @ 200 c/c

Use M20 concrete and Fe 415 steel

Draw longitudinal and cross section if the beam is

1.T-beam

2.Inverted T-beam

3.L-Beam

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PROBLEM No. 6

Main positive reinforcement @ end span = 8 mm diameter @100 c/c

Main reinforcement in other interior panels = 8 mm diameter @ 200 c/c

Negative reinforcement @ all supports = 8mm diameter @ 200 c/c

Distribution steel= 8 mm diameter @ 200 c/c

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Slab spanning in one direction (One-way slab)

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Slab spanning in two-directions (two-way slab)

 

 

Typical BBS Calculation

Example: Prepare bar bending schedule for the given beam. Clear cover = 40 mm

Frequency of Tests

Preparing Daily Construction Reports

Why do we need Daily Construction Reports?

It is part of the business and daily routine.

• To review important notations in weekly meetings to set up action lists/agendas and improve performance through discussion.
• To compliment good reports that briefly convey important items.
• Daily Reports are working documents of the business.

It is needed for legal aspects and purposes.

• Daily Reports are documents that can testify the activities that did happen, or did not happen but should have happened on site.
• It can be introduced in court as evidence of the activities on site.

Things/Factors that a Daily Report Supports:

• Time and Material Costs under the “Change” clause
• Constructive Changes
• Acceleration of Work
• Suspension of Work
• Impacts and Delays
• Changes in the Sequence of Activities
• Disruptions
• Force Stoppage of Work
• Termination of Work

Things to Avoid in Daily Reports:

• Inaccuracies
• Self-serving Statements
• Inconsistencies
• Loss of Records

What do you need:

• A hard-backed pad or clipboard and a pen
• A small durable tape or digital voice recorder
• A digital camera with date and time stamp
• A flashlight and tape measure
  

Be sure to have an answer to the following:

• Actual start of an activity. If it’s delayed, why?
• Were all items needed to start on hand/ready?
• Were any activities stopped /postponed for any reason?
• When is the completion of an activity?

Important Aspects on a Daily Report:

• Get and list names.
• Note time of day.
• Be specific about location.
• Separate fact from opinion.
• Think cause-and-effect.
• Include lots of photos.
• Think safety!

Other noteworthy items:

• Tests and their results
• Inspections with pass/fail information
• Major material deliveries (complete, damage, correct, etc.)
• Job site visitations and reasons (arrive/leave info)
• Shared crane usage
• People issues

 

Categories of Labors in Building Industry

Life of Various Items of Works in Building

Materials Required for Different Items of Construction

The table below shows the quantities of materials required  for different items in construction: 

Task Work

The  task work stated below is to be used as a guidance only and should not be quoted as a rule.

Checks Over the Accuracy of Detailed Estimates

In order to ensure that the quantities of the various items worked out in a detailed estimate are fairly correct, it is necessary to apply cross-checks as specified:

 

Damp Proof Course (D.P.C)

• Damp proof course about 25 mm thickness in cement concrete (1:1.5:3 or 1:2:4) combined with standard water proofing agent is applied evenly to the entire width of plinth level and is measured by multiplying the length of the D.P. course by its width in square metres. D.P.C. is not to be applied at the verandah openings, sills of the  doors, etc. for which necessary deductions are to be made from the measured quantity.
• The D.P.C. in horizontal and vertical directions are to be measured separately.
• Guniting: Full description of the item shall be specified mentioning the thickness. The item shall be measured in square metres.

Construction Activities and Process

Schedule of Work

• Site preparation

1. Survey work: 1 week
2. Setting out: 1 week
3. Earthwork: 1-2 weeks

• Foundation

1. Pile: 3 weeks
2. Pile cap: 2 weeks
3. Stump: 2 weeks
4. Ground Beam: 2 weeks

• Ground Floor

1. Slab: 2 weeks
2. Column: 2 weeks
3. Beam: 2 weeks
4. Staircase: 2 weeks
5. Wall: 2 weeks
6. Plastering: 2 weeks

• First Floor

1. Slab: 2 weeks
2. Column: 2 weeks
3. Beam: 2 weeks
4. Staircase: 2 weeks
5. Wall: 2 weeks
6. Plastering: 2 weeks

• Second Floor

1. Slab: 2 weeks
2. Column: 2 weeks
3. Beam: 2 weeks
4. Staircase: 2 weeks
5. Wall: 2 weeks
6. Plastering: 2 weeks

• Roof Slab

Utility

1. Electrical Supply: 1 week
2. Water Supply: 1 week
3. Door and Windows Total: 2 week

Finishes

1. 1st floor Kitchen Plumbing: 1 week
2. Plastering interiors 1st floor: 2 week
3. Plastering Interiors 2nd floor: 1 week
4. Skidding floors Painting – first coat: 2 week
5. Painting – second coat: 2 week
6. Sanitary fitting of bathroom and kitchen: 1 week
7. Electrical fitting: 1 week .

Total: 57 week

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WEEK 1
Activity 1: Site survey

Duration: 7 days

Materials: –

Equipment:-

Skilled Workers: Backhoe Loader Operator(1), General workers(4), Lorry driver(1)

Technical Information: Analysis is done to the construction site by surveyor and further planning and advices to the site for construction preparation and development.

Activity 2: Mobilization

Duration: 2-3 days

Materials: Machineries

Equipment: Lorries(2), mobile crane(1), backhoe loaders(1), Hydraulic Piling Hammer(1), excavator(1), compactor (1), boring machine(1)

Skilled Workers: lorry drivers(2), excavator operator(1), backhoe loader operator(1), Hydraulic Piling Hammer operator(1), compactor operators (1), boring machine operator(1)

Technical Information: Machineries required is delivered to the site and wait for job to be executed.

Activity 3: Site Clearing

Duration: 7 days

Materials: –

Equipment: Backhoe Loader, chainsaw, lorry truck (carry earth & plants away)

Skilled Workers: Backhoe Loader Operator(1), General workers(4), Lorry driver(1)

Technical Information: Excavation of unfavorable soil and substances such as stones and tree barks. Initial leveling is done for the preparation of earthwork.

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WEEK 2
Activity 1: Hoarding (setting out), staking (plan boundary)

                    

Duration: 5 days

Materials: blue metal decks, nails, wooden pegs, planks, stakes, Builder’s line

Equipment: hammer, measuring tape, theodolite, Dummy level, construction sign board

Skilled Workers: quantity surveyor (2), general workers (4)

Technical Information: Boundary of the construction site is precisely measured and borders the site where the construction takes place. The site is marked with gridlines with a setback of 20 feet from the road and 10 feet for the porch according to UBBL and the location of the pile is marked.

Activity 2: Earthwork

Duration: 7 days

Materials: –

Equipment: excavator, compactor

Skilled Workers: Excavator Operator (1), Compactor Operator (1)

Technical Information: Removal of top soil and land leveling. The land is excavated to around 300mm of the top soil. Keep away or stored well for reuse due to its high water retentive characteristic.

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WEEK 3
Activity 1: Earthwork (continued)

Duration: 7 days (continued from last week)

Materials: –

Equipment: excavator, compactor

Skilled Workers: Excavator Operator (1), Compactor Operator (1)

Technical information: Removal of top soil and land leveling. The land is excavated to around 300mm of the top soil. Keep away or stored well for reuse due to its high water retentive characteristic.

Activity 2: Piling (Grid 13- Grid 15)

 

Duration: 10-14 days

Materials: Reinforced concrete piles, Concrete Grade 30, Reinforcement, wooden formworks

Equipment: Hydraulic Piling Hammer(1), Rebar Bending machine(1), Boring Machine(1), cement concrete mixer (1), hacker (1)

Skilled Workers: Hydraulic Piling Hammer Operator (1), Boring Machine Operator (1), Rebar Bender (1), General construction workers (6)

Technical Information: The depth/length of the piles is depending on the soil condition based on the soil test, after that the engineers will decide the pile length to fit the soil condition of the site, based on the result of the test. Difference in height of the piles will be cut below cap using hacker. The rebar connected to the piles are then removed and left for the joining of capping reinforcement. Soil specimen is taken for soil test experiment to determine the length of the pile. The pile integrity test (Load test) is done to determine the strength to support the load.

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Week 4

Activity 1: Piling (Grid 8 – Grid 12)

    

Duration: 10-14 days

Materials: Reinforced concrete piles, Concrete Grade 30, Reinforcement, wooden formworks

Equipment: Hydraulic Piling Hammer(1), Rebar Bending machine(1), Boring Machine(1), cement concrete mixer (1)

Skilled Workers: Hydraulic Piling Hammer Operator (1), Boring Machine Operator (1), Rebar Bender (1), General construction workers (6)

Technical Information: The depth/length of the piles is depending on the soil condition based on the soil test, after that the engineers will decide the pile length to fit the soil condition of the site, based on the result of the test. Difference in height of the piles will be cut below cap using hacker. The rebar connected to the piles are then removed and left for the joining of capping reinforcement. Soil specimen is taken for soil test experiment to determine the length of the pile. The pile integrity test (Load test) is done to determine the strength to support the load.

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Week 5
Activity 1: Leveling of Piles before capping

Duration: 3 days

Materials: Reinforced concrete piles, Concrete Grade 30, Reinforcement, wooden formworks

Equipment: Hydraulic Piling Hammer(1), Rebar Bending machine(1), Boring Machine(1), cement concrete mixer (1)

Skilled Workers: Hydraulic Piling Hammer Operator (1), Boring Machine Operator (1), Rebar Bender (1), General construction workers (6)

Technical Information: When the piling is penetrated into the soil, the piles are in different height. The piles need to be cut before cap by using hacker. The rebar are removed and then the capping reinforcement are applied.

Activity 2: Pile capping

      

Duration: 7 -14 days

Materials: Reinforced concrete piles, Concrete Grade 30, Reinforcement, wooden formworks

Equipment: Hydraulic Piling Hammer(1), Rebar Bending machine(1), Boring Machine(1), cement concrete mixer (1)

Skilled Workers: Hydraulic Piling Hammer Operator (1), Boring Machine Operator (1), Rebar Bender (1), General construction workers (6)

Technical Information: pile caps takes around 2 weeks to reach its maximum strength, but usually it can be done after it is left curing for about a week. Stumping can be constructed around that time.

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Week 6
Activity 1: Stump from Pile caps

   

Duration:7 days-14 days

Materials: Concrete Grade 30, reinforcements, timber formworks.

Equipment: Concrete Vibrator(1), Rebar bending machine(1), tablesaw(1)

Skilled Workers: Land Surveyor (1), Carpenter(2), Bar Bender (1), General worker (2)

Technical Information: After pilings , the land surveyor will identity of the height required of the stumps and thereafter construct the stumps based on the data. Steel rebar are bent into cage form, with starter bar protruding upward to connect for latter construction of columns. Constructed the same way as the pile capping, the stumps are left for curing in order to achieve its required structural strength before the construction of the beams. It is left to cure for a week.

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WEEK 7
Activity 1: Ground Beam (Grid 13-Grid 17)

 

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks,

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical information: Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting form and left for curing around a week time.

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WEEK 8
Activity 1: Ground Beam (Grid 8-Grid 13)

 

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks,

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical information: Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting form and left for curing around a week time.

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Week 9
Activity 1: Ground floor slab (grid 12- grid 17)

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beam, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting form and left for curing around a week time. DPM is laid on the concrete and screeded with long even plank.

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Week 10
Activity 1: Ground floor slab (grid 8 – 12 ,continued from the first )

 

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beam, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting form and left for curing around a week time. DPM is laid on the concrete and screeded with long even plank.

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Week 11
Activity 1: Ground Floor Columns (Grid 12 – Grid 15)

 

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: Same as the construction of beams, the formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

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Week 12
Activity 1: Ground Floor Columns (Grid 8-Grid 11)

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: Same as the construction of beams, the formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

 

Activity 2: First Floor Beam (Grid 12- Grid 17) , first half

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: The formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

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Week 13
Activity 2: First Floor Beam (Grid 8 – Grid 12) , second half

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: The formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

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Week 14
Activity 1: First Floor Slab (Grid 13-grid 17)

 

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beams, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting, screeded with plank and then left for curing around a week time. A layer of protection is laid on top of the concrete during curing.

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Week 15
Activity 1: First Floor Slab ( second half floor)

 

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beams, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting, screeded with plank and then left for curing around a week time. A layer of protection is laid on top of the concrete during curing.

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Week 16
Activity 1: first floor column (grid 12-grid 17), first half

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: Same as the construction of beams, the formwork is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

 

Activity 2: Ground Floor Staircase (to level 1)

Duration: 8-14 days

Materials: Concrete Grade 30, reinforcements, timber formworks,

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1), spirit level.

Skilled Workers: Carpenter (2), Rebar Bender (1), General worker (3)

Technical Information: The formworks of the stairs is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time. A concrete test is taken to check the strength of the casting after it was left to cure for a week.

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Week 17
Activity 1: first floor column (grid 8-grid 12), second half

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: Same as the construction of beams, the formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.
Activity 2: Second Floor Beam (Grid 12- Grid 17) , first half

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: The formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

 
Activity 3: Ground Floor Staircase (to level 1, continued)

Duration: 8-14 days

Materials: Concrete Grade 30, reinforcements, timber formworks,

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1), spirit level.

Skilled Workers: Carpenter (2), Rebar Bender (1), General worker (3)

Technical Information: The formworks of the stairs is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time. A concrete test is taken to check the strength of the casting after it was left to cure for a week.

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Week 18
Activity 1: Second Floor Beam (Grid 8- Grid 12) , second half

  

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: The formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

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Week 19
Activity 1: Second Floor Slab (first half)

 

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beams, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting, screeded with plank and then left for curing around a week time. A layer of protection is laid on top of the concrete during curing.

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Week 20
Activity 1: Second Floor Slab (second half)

 

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beams, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting, screeded with plank and then left for curing around a week time. A layer of protection is laid on top of the concrete during curing.

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Week 21
Activity 1: Second floor column (grid 8-grid 13)

Duration: 14 Days

Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: Same as the construction of beams, the formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

 

Activity 2: First Floor Staircase (to level 2)

Duration: 8-14 days

Materials: Concrete Grade 30, reinforcements, timber formworks,

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1), spirit level.

Skilled Workers: Carpenter (2), Rebar Bender (1), General worker (3)

Technical Information: The formworks of the stairs is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time. A concrete test is taken to check the strength of the casting after it was left to cure for a week.

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Week 22
Activity 1: Roof floor Beams (Grid 8- Grid 13) , All floor

 

Duration: 14 Days Materials: Concrete Grade 30, reinforcement, timber formwork

Equipment: Concrete Mixer(1), Concrete vibrator (1) , bar bending machine (1), table saw

Skilled worker: Carpenter (2) , bar bender (2), general worker (4)

Technical information: The formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pouring into the casting form and left for curing around a week time.

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Week 23
Activity 1: third floor Slab (all floor)

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beams, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting, screeded with plank and then left for curing around a week time. A layer of protection is laid on top of the concrete during curing.

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WEEK 24
Activity 1: Brickwalls Ground Level (Grid 3- 4)

  

Duration: 15-20 days

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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WEEK 25
Activity 1: Brickwalls Ground Level (Grid 4-5)

 

Duration: 15-20 days

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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Week 26

Activity 1: Brickwalls Ground Level (Grid 5-6)

  

Duration: 15-20 days

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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Week 27
Activity 1: Brickwall First Level (Grid 3-4)

 

Duration: 15-20 days

Materials: 100 mmx 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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Week 28
Activity 1: Brickwall First Level (Grid 4-5)

 

Duration: 15-20 days

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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Week 29
Activity 1: Brickwall First Level (Grid 4-5)

Duration: 15-20 days

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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Week 30
Activity 1: Brickwall Second Level (Grid 3-4a)

 

Duration: 15-20 days

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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Week 31 

Activity 1: Brickwall Second Level (Grid 4a-5)

 

Duration: 15-20 days  

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

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Week 32
Activity 1: Brickwall Second Level (Grid 13 -17)

Duration: 15-20 days

Materials: 100 mm x 215 mm x 75 mm Clay Bricks, Cement mortar, Builder’s line, Wire mesh reinforcement

Equipment: Wheel barrow (2), Shovel (2), Groovers (5), Edges (5)

Skilled Workers: General Workers (6)

Technical Information: Builder’s line is used to alight the walls during stacking of bricks and construction of the wall. The clay bricks are bonded with mortar and stack together with specific bonding pattern. Wire mesh is laid on the bricks in certain layer interval as reinforcement and stiffer will be constructed between walls to strengthen the walls.

Activity 2: Façade roof slab

Duration: 14 days

Materials: Concrete Grade 30, reinforcements, timber formworks, Damp Proof Membrane (DPM), Rigid Floor Insulation, screed plank

Equipment: Concrete Vibrator(1), Rebar bending machine(1), table saw(1), concrete mixer(1),

Skilled Workers: Carpenter(2), Rebar Bender (1), General worker (3)

Technical Information: The Ground slab is cast after beam, the workers can proceed to next construction during curing time. Formworks is constructed with steel rebar reinforcement and starter bar. Thereafter a mixture of concrete with aggregates and cement is then pour into the casting form and left for curing around a week time. DPM is laid on the concrete and screeded with long even plank.

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Week 33
Activity 1: Framing (ground floor)

Duration: 7 days

Materials: Openings wooden frame (for door and windows)

Equipment: Spirit level, Measuring tape

Skilled Workers: General Workers (4)

Technical Information: The opening frames are constructed in position and align after the brick wall is done. Architrave is added after the door/window frame is added.
Activity 2: Incoming Electrical Circuit Supply Installation

Duration: 10-14 days

Materials: Copper Cables (different sizes), Kilowatt hour meter

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts,

Skilled Workers: Electric Technician (2), Plumbers (2)

Technical Information: Incoming electricity cables are brought into the house and connected to a circuit box in the house to facilitate the plumbing works later on.

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Week 34
Activity 1: Framing (First floor)

Duration: 7 days

Materials: Openings wooden frame (for door and windows)

Equipment: Spirit level, Measuring tape

Skilled Workers: General Workers (4)

Technical Information: The opening frames are constructed in position and align after the brick wall is done. Architrave is added after the door/window frame is added.

Activity 2: Incoming Electrical Circuit Supply Installation

Duration: 10-14 days (continued)

Materials: Copper Cables (different sizes), Kilowatt hour meter

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts,

Skilled Workers: Electric Technician (2), Plumbers (2)

Technical Information: Incoming electricity cables are brought into the house and connected to a circuit box in the house to facilitate the plumbing works later on.

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Week 35
Activity 1: Framing (Second floor)

Duration: 7 days

Materials: Openings wooden frame (for door and windows)

Equipment: Spirit level, Measuring tape

Skilled Workers: General Workers (4)

Technical Information: The opening frames are constructed in position and align after the brick wall is done. Architrave is added after the door/window frame is added.

Activity 2: Ground Floor Plumbing (First Fix)

Duration: 14 days

Materials: Copper Cables (different sizes), PVC pipes, socket box

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts, Hacking machine

Skilled Workers: Electricians(2), Plumbers (2)

Technical Information: Technicians will determine the location of the sockets according to the engineering blue print. The brick wall is hacked to accommodate the wiring pipe from the top to the ground according UBBL requirements. The wall sockets will be installed after the wiring is done.

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Week 36
Activity 1: First Floor Plumbing (First Fix)

Duration: 14 days

Materials: Copper Cables (different sizes), PVC pipes, socket box

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts, Hacking machine

Skilled Workers: Electricians(2), Plumbers (2)

Technical Information: Technicians will determine the location of the sockets according to the engineering blue print. The brick wall is hacked to accommodate the wiring pipe from the top to the ground according UBBL requirements. The wall sockets will be installed after the wiring is done.

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Week 37
Activity 1: First Floor Plumbing (First Fix)

Duration: 14 days

Materials: Copper Cables (different sizes), PVC pipes, socket box

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts, Hacking machine

Skilled Workers: Electricians(2), Plumbers (2)

Technical Information: Technicians will determine the location of the sockets according to the engineering blue print. The brick wall is hacked to accommodate the wiring pipe from the top to the ground according UBBL requirements. The wall sockets will be installed after the wiring is done.

Activity 2: Second Floor Plumbing (First Fix)

Duration: 14 days

Materials: Copper Cables (different sizes), PVC pipes, socket box

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts, Hacking machine

Skilled Workers: Electricians(2), Plumbers (2)

Technical Information: Technicians will determine the location of the sockets according to the engineering blue print. The brick wall is hacked to accommodate the wiring pipe from the top to the ground according UBBL requirements. The wall sockets will be installed after the wiring is done.

Activity 3: Plumbing (Sanitary and Kitchen)

Duration: 14 days

Materials: Copper Cables (different sizes), PVC pipes, socket box

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts, Hacking machine

Skilled Workers: Electricians(2), Plumbers (2)

Technical Information: Technicians will determine the location of the sockets according to the engineering blue print. The brick wall is hacked to accommodate the wiring pipe from the top to the ground according UBBL requirements. The wall sockets will be installed after the wiring is done.

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Week 38
Activity 1: Plumbing (Sanitary and Kitchen)

Duration: 14 days

Materials: Copper Cables (different sizes), PVC pipes, socket box

Equipment: Voltmeter, Ammeter, Plyers, Screws and nuts, Hacking machine

Skilled Workers: Electricians(2), Plumbers (2)

Technical Information: Technicians will determine the location of the sockets according to the engineering blue print. The brick wall is hacked to accommodate the wiring pipe from the top to the ground according UBBL requirements. The wall sockets will be installed after the wiring is done.

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Week 39
Activity 1: Ground floor Wall Plastering (Grid 1-Grid 3)

 

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The first coating thickness is around 1/2 to 3/4 inches while the finishing coat will be around 3/16 inches thick. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

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Week 40
Activity 1: Ground floor wall plastering (Grid 4-4a)

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The first coating thickness is around 1/2 to 3/4 inches while the finishing coat will be around 3/16 inches thick. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

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Week 41
Activity 1: Ground floor plastering (Grid 4a-6)

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The first coating thickness is around 1/2 to 3/4 inches while the finishing coat will be around 3/16 inches thick. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

Activity 2: First floor plastering (Grid 1- Grid 4)

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

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Week 42
Activity 1: First floor plastering (Grid 4- Grid 4a)

 

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The first coating thickness is around 1/2 to 3/4 inches while the finishing coat will be around 3/16 inches thick. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

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Week 43
Activity 1: First floor plastering (Grid 4a-6)

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

Activity 2: Second floor plastering (Grid 1-Grid 4)

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

Activity 3: Ground Floor Tiling (Grid 13- Grid 17)

 

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

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Week 44
Activity 1: second floor plastering (Grid 4-4b)

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The first coating thickness is around 1/2 to 3/4 inches while the finishing coat will be around 3/16 inches thick. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

Activity 2: Ground Floor Tiling (Grid 10-13)

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

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Week 45
Activity 1: Second floor plastering (Grid 4b-6)

Duration: 14-21 days (interior and exterior)

Materials: cement plaster, skim coat

Equipment: buckets, cement spatula trowels, groovers, edgers, planks, sponges, scaffolding, plaster spray

Skilled Workers: general workers (2), plasterers(3)

Technical information: The plaster layer is not more than half inches, and left for drying about 7 days before the finishing is applied. The first coating thickness is around 1/2 to 3/4 inches while the finishing coat will be around 3/16 inches thick. The surface of the rendering preferably wetted before application of plastering. Rough surface plastering is usually used outdoor to resist harsh weathering. Smooth surface plastering with pores and easily defected characteristic is preferably used indoor.

Activity 2: Ground Floor Tiling (Grid 8- Grid 10)

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

 

Activity 3: First Floor Tiling (Grid 14-17)

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

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Week 46
Activity 1: First Floor Tiling (Grid 10-14)

 

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

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Week 47
Activity 1: First Floor Tiling (Grid 8-10)

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

Activity 2 : Second Floor Tiling (Grid 10 – Grid 13)

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

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Week 48
Activity 1: Second Floor Tiling (Grid 8- Grid 10)

Duration: 14-21 days

Materials: Ceramic tiles, Cement mortar, Silicone sealant

Equipment: Spirit level (1), Groovers (3), Tile cutter (1), Carpenter’s square (1)

Skilled Worker: General worker (2)

Technical Information: Tiles are precisely measured according to the application area of the building. This can help to save number of tiles and as well able to maximize the applying area. The tile will be cut into varies sizes and shapes to fit those with smaller surface area.

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Week 49
Activity 1: Finishing – undercoat (Ground floor)

 

Duration: 21 days

Materials: Wall Sealer

Equipment: Edgers, groovers, screed plank, Paint brushes, Point rollers

Skilled Worker: Painter (5)

Technical Information: Sealer is required to seal the holes, hairline cracks of the walls. The walls are needed to seal to prevent the drywall from absorbing the moisture and the paint. By applying a layer of sealer, it gives the wall an adhesive base for the paint to stick on firmly without having bubbling and waterborne stain.

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Week 50:
Activity 1: Finishing – Undercoat (First floor)

Duration: 21 days

Materials: Wall Sealer

Equipment: Edgers, groovers,plank, Paint brushes, Point rollers

Skilled Worker: Painter (5)

Technical Information: Sealer is required to seal the holes, hairline cracks of the walls. The walls are needed to seal to prevent the drywall from absorbing the moisture and the paint. By applying a layer of sealer, it gives the wall an adhesive base for the paint to stick on firmly without having bubbling and waterborne stain.

Activity 2: Painting – Uppercoat (Ground floor)

Duration: 14 days

Materials: Paint

Equipment: Paint brush (3), Point roller (3)

Skilled Worker: Painter (5)

Technical Information: Painting for finishing should be done after the plastering and undercoating are completely dried up to prevent bubbling of the wall due to the moisture. Painting requires few layers for better surface finishes.

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Week 51
Activity 1: Finishing – Undercoat (Second floor)

 

Duration: 21 days

Materials: Wall Sealer

Equipment: Edgers, groovers,plank, Paint brushes, Point rollers

Skilled Worker: Painter (5)

Technical Information: Sealer is required to seal the holes, hairline cracks of the walls. The walls are needed to seal to prevent the drywall from absorbing the moisture and the paint. By applying a layer of sealer, it gives the wall an adhesive base for the paint to stick on firmly without having bubbling and waterborne stain.

Activity 2: Painting – First coat (First Floor)

 

Duration: 14 days

Materials: Paint

Equipment: Paint brush (3), Point roller (3)

Skilled Worker: Painter (5)

Technical Information: Painting for finishing should be done after the plastering and undercoating are completely dried up to prevent bubbling of the wall due to the moisture. Painting requires few layers for better surface finishes.

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Week 52
Activity 1: Painting – First coat (Second Floor)

 

Duration: 14 days

Materials: Paint

Equipment: Paint brush (3), Point roller (3)

Skilled Worker: Painter (5)

Technical Information: Painting for finishing should be done after the plastering and undercoating are completely dried up to prevent bubbling of the wall due to the moisture. Painting requires few layers for better surface finishes.

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Week 53
Activity 1: Doors, Windows and Screens installation

Duration: 10-14 days

Materials: precast aluminum window frames, doors, glass windows panels, door frames, pre-manufactured wooden,wooden crossed screen , screws, sealer

Equipment: Bolts and Nuts, Screwdriver and related toolkit.

Skilled worker: General worker (4)

Technical information: The doors and windows are then installed to the walls, replacing the temporary frames and secured with screws and sealer.

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Week 54
Activity 1: Doors, Windows and Screens installation

  

Duration: 10-14 days (continued)

Materials: precast aluminum window frames, doors, glass windows panels, door frames, pre-manufactured wooden,wooden crossed screen , screws, sealer

Equipment: Bolts and Nuts, Screwdriver and related toolkit.

Skilled worker: General worker (4)

Technical information: The doors and windows are then installed to the walls, replacing the temporary frames and secured with screws and sealer. Prefabricated screen is secured with fixtures and nut onto the walls.

Activity 2: Electrical & Sanitary fittings

Duration: 14 days

Materials: Wall sockets, Wall plugs and bathroom porcelain appliances

Equipment: Bolts and Nuts, Screwdriver and related toolkit.

Skilled worker: General worker (4)

Technical information: Standard electrical appliances are then fixed during the last phase.

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Week 55
Activity 1: Pavings

Duration: 10-15 days

Materials: paving stones, bricks, Concrete Grade 30, reinforcements, timber formworks,plank

Equipment: wheel barrow, Concrete Mixer(1), (1), table saw

Skilled Workers: general workers (4)

Technical information: Paving stones to be laid on the soil as pavement of walkway, parking, and garden.

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Week 56
Activity 1: Pavings

Duration: 10-15 days (continued)

Materials: paving stones, bricks, Concrete Grade 30, reinforcements, timber formworks,plank

Equipment: wheel barrow, Concrete Mixer(1), (1), table saw

Skilled Workers: general workers (4)

Technical information: Paving stones to be laid on the soil as pavement of walkway, parking, and garden.

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Week 57
Activity 1: Grass turfing – External work

Duration: 7 days

Materials: lawn turf rolls (depends on the size of garden), bricks

Equipment: wheel barrow, gardening tool kits, water pipes

Skilled Workers: lawn turf layers(2), general workers (2)

Technical information: Soil preparation is done before laying the rolls of grass turf on the soil surfaces. Excavated soil can be reused as the base of the courtyard. Loose stones and building rubble will prevent the turves roots from making contact with the soil and could make the turf die in patches. The top soil should then be thoroughly rotivated down to about the first 6 inches to aerate it properly. It is then raked level and gently treaded down.