beam hand book

Hand book RCC Beam

Snehal Hiranandani Group Of Companies. Pg- 1

Hand Book on

RCC Beam

Hiranandani Group Of Companies.

Hand book RCC Beam


This hand book describes some of the important aspects and specifications of RCC beams with respect to shuttering, reinforcement, concreting and curing. This hand book shall be referred along with constructions syllabus, slab hand book and relevant general drawings ,provided by the RCC Consultant.

Shuttering.

1. Beam bottom topi fixing is done with nut bolts and yokes as shown in picture. No nailing shall be done for fixing topi with column.

2. Typical cross section of beam shuttering is shown in sketch. Please note the corner detail of beam bottom with beam side. No wadhara ( Beam side should not project below beam

bottom ) is permitted. Also no Acrow spans should be used for beam bottom shuttering. First prop of beam bottom shall be 225mm from the Column face .

Hand book RCC Beam


H

W

Detail A

Beam Side (12mm Ply)

Wailing

Stud

Beam Bottom (12mm Ply)

Typical Beam Shuttering Corner Joint Detail

Leak Proof System

AX

Y

Z

Z

12mm

12mm

Beam Bottom Wailing X

Beam Side Plywood

Beam Side Wailing Y

3. Normally all beams are having uniform depths and widths. For eg. Beam depth is kept 500 mm for floor height of 2900mm, and 600mm for floor height of 3000mm. This helps engineer to cast all columns to standard height of 2400mm. Details of beam depth and floor height may vary building to building. As far as beam widths are concerned, it is generally 225 mm, 300mm or 125mm. Normally 125mm width is provided for exterior beams , in special cases only . Picture shows uniform depths of beams.

Hand book RCC Beam


4. In case of Elevator entrance beam, depth shall be 350mm , so that if required we can provide a door height of 2300mm & thereby provide a tall car of 2500mm or 2600mm height , if required .

5. Shuttering of beams shall be done as per approved designs and sketches. Design of shuttering includes materials to be used, section of wooden members, spacing etc.

6. In beam bottom props door system is kept to allow carpenters to walk and to transport shuttering materials etc. Proper planning shall be done so that carpenters , do not disturb beam bottom props , while removing shuttering materials.

Hand book RCC Beam


7. Gap between external and exterior beams shall be min 375mm so that carpenters can easily erect and remove beam sides between the beams.

Picture showing external and exterior beams with nib in between. The one resting directly on column is external beam ( left side ) and one which is out side building line is exterior beam ( right side)

8. Working platform is provided for exterior beams so that carpenters can stand safely on working platform to erect and remove exterior beams shuttering, and to get proper alignment of shuttering. Below picture shows platform provided. Min. three , 9 inches width planks shall be placed for person to stand.

Hand book RCC Beam


9. In case of Double height slab with tie beams (especially at Entrances of buildings ) , one can cast column in one shot leaving dowels for tie beams and carry out shuttering for first slab as seen in picture.

Hand book RCC Beam


10.Column beam junction shuttering requires extra attention ,so that we get good finish after casting which is free from slurry leakage, offsets and bulging. Back to back angles with bolts are provided as shown in picture. Also put ply wood extension packing on beam sides at column beam junction to prevent slurry leakage as shown in sketch.

Hand book RCC Beam


PIECE OF PLYWOOD GENRALLY INSERTED AFTERWORDS

12 MM PLYWOOD

4"x1 12"WAILLING PATTI

STUD

COLUM

10. In case of toilet beams, care shall be taken to see that any sunk is required in the beams. Sunk can be 65mm or 250mm depending on location of beams and location of walls.

Hand book RCC Beam


Picture showing toilet slab ceiling

11. Beam bottom can also be erected using ISLB 100x50mm as shown in picture , but it should be noted that ISLB 100 X 50 mm , should not be mixed preferably & used with the conventional system of providing beam bottom props ( especially , do not provide ISLB

100 X 50 mm , upto approximately center of beam & rest with conventional beam bottem props ) .

Hand book RCC Beam


12. All beam bottom props shall be braced so that they do no get displaced after casting of slab. Bracing can be wooden patti or bamboo .

13. Use beam width gauges ( kanda ) of appropriate sizes to ensure correct beam widths. These wooden gauges shall be placed in position at the time of shuttering.

14. Usually external beam face is kept 75mm out from the column face as shown in sketch , for beams , having large windows to have a larger width of window sill. For beams having , small windows like kitchen window, beam width is kept 300mm only for window width , instead of taking beam out by 75mm.

Hand book RCC Beam


9"12"

WALLBEAM

WINDOWY

YSmall Windows

9"

WINDOW X

X BEAM 9" WIDTH IS OUT BY 3"

Large Windows.

3"

6"

15. Normally no beams shall be provided between living room and dining room. RCC consultant shall be informed to design slab accordingly.

16. All shuttering which is not giving required line, level and finish shall be replaced, especially at upper floors.

17. No camber shall be provided in beam bottom unless otherwise specified by the RCC consultant.

Hand book RCC Beam


18. Maximum care shall be taken to ensure perfect level of beam bottom. It is normally observed that due to improper (hogging / sagging / wavy) beam bottom level, gaps are coming between aluminum window frames and beam bottoms , which effects the smooth operation of Aluminium Window shutters .

19. Wedges are provided in case of wooden beam bottom props for leveling purpose.

20. All relevant checklists shall be signed for beam bottom.

21. Beam side corner shuttering shall be done in such a way that only plywood surface comes in contact with concrete as shown in picture. This gives good finish to rcc surface.

22. Use appropriate systems like turn buckle etc for preventing sway of large spans beams. This is important especially in case of commercial buildings. Hooks can be left in slab for fixing turn buckle as shown in picture.

Hand book RCC Beam


23. In case of very heavy brackets, deep beams, one must plan shuttering and staging well in advance and necessary arrangements in terms of hooks, shuttering materials, and necessary designs must be done and got approved.

Hand book RCC Beam


24. If required, one can provide M.S brackets for beam side shuttering, especially in case when it is not possible to take out platform with raker support, for eg. behind Elevator shear wall , long shear wall etc.

Hand book RCC Beam


25. All electrical conduits are touched to beam bottom and not punctured. All these electrical conduits shall be tied with reinforcement to prevent displacement during concreting.

26. Extra care shall be taken especially for staircase beam side top sway, by fixing at the Top edge of the beam , a horizontal timber along the length of the beam is fixed , which will not allow the beam side top , to sway .

Hand book RCC Beam


27. All exterior beams shall be suitably connected to external beams using wooden members to prevent sway of exterior beams.

28. Especially in case of sunk with adjacent columns, one must take care to see that sides are erected properly otherwise it results in reduction of column section as shown in fig.

Picture shows reduction of columns section at beam top level due to faulty beam side shuttering.

29. Provide Beam stopper as shown in picture. This ensures that no concrete flows near construction joints and full compaction is ensured near stopper.

Hand book RCC Beam


Picture showing poor beam stopper resulting in flow of concrete.

Picture showing correct beam end stopper.

Reinforcement

Hand book RCC Beam


30. Normally column is cast up to beam bottom level and at column beam junction also concrete can flow below beam reinforcement. Some times it is observed that due to column cast is more than required, beam reinforcement rest on column top and thus no fresh concrete can flow below beam reinforcement affecting bonding of beam bottom reinforcement. Hence such situation shall be avoided by casting columns to correct height.

31. Make sure that there are sufficient gaps between reinforcement to pass 60mm dia needle vibrator. Reinforcement shall be re arranged / bundled in consultation with RCC consultant to ensure this. For eg. One can not have 3 nos of 32 dia bars on top for 225mm width beam bottom. Either beam width shall be increased or bars shall be placed in layers with pin in between.

Incorrect

vibrator to go inside.Insufficient space for Sufficient space

for vibrator to go inside

Correct 20 mm

32. Clear cover to beam reinforcement shall be as shown in sketch below.

Hand book RCC Beam


40mm

Slab

40mm

External beam.

40mm.

150mm thick.Nib.40mm.40mm.

Exterior beam.

40mm

40mm

40mm

40mmInternal beams

40mm

40mm

40mm

25mmslab

20mm20mm

33. Follow all ductility requirements for reinforcement as shown in Gen. drg. of RCC consultant. Few important details are as shown in pictures.

Hand book RCC Beam


Picture showing stirrups in column beam junction.

Picture showing 45 degree bend in beam stirrups.

34. For exterior beams are 125mm in width, S hook reinforcement is provided as shown in picture.

Hand book RCC Beam


35. Care shall be taken to ensure that binding wire knots and tails are not projecting in the cover zone.

36. At the intersection of two beams, care shall be taken to joggle reinforcement of one of the beams so that top cover is maintained.

37. Beam joggling shall be done gradually (1:6) near columns. Provide first stirrups at 40mm from the face of column.

Hand book RCC Beam


38. Necessary arrangement shall be done to ensure sufficient space for 60mm needle vibrator to penetrate in column beam junction. In case of heavy congestion, inform RCC consultant to revise junction details. Similarly at the intersections of beams with heavy congestions, one must create pockets for vibrator to go inside

39. Provide cover gauge for beam side cover as shown in picture. Gauges shall be placed opposite to each other to ensure correct cover to beam reinforcement.

Hand book RCC Beam


40. Provide inverted chipya in column beam junction if sufficient space is not available for 60mm needle vibrator to penetrate vertically.

41. Special tool is used to turn stirrups in column- beam junction as shown in picture

Hand book RCC Beam


42. Top cover of beams in case of flat slab shall be kept such that we get required top cover for the flat slab reinforcement. This is because flat slab reinforcement is resting on external beams.

43. Any cut outs to be provided in beams shall not interfere with beam reinforcement. RCC consultant shall be informed about the provision of cut outs and beams shall be suitably designed for these cut outs.

44. For large cantilevers, deep beams, large spans etc location of lapping shall be confirmed by the RCC consultant.

45. Normally columns are cast upto beam bottom level and no topi concrete is permitted. But if topi concrete is unavoidable, make sure that needle vibrator can penetrate below lowest beam bottom reinforcement. Engineer must make sure that concrete in topi zone is vibrated. This is required to avoid any honey combing in topi zone as shown in sketch.

COLUMN TOPI

BEAM BOTTOM LEVEL.

POORLY VIBRATED CONCRETECAN RESULT IN HONEY COMBING

COLUMN

BEAM BOTTOM STEEL

NEEDLE VIBRATOR

COLUMN CONCRETE

Hand book RCC Beam


Picture showing honeycombing in column topi portion. Column was not cast up to beam bottom level and vibrator could not pass through beam bottom reinforcement.

46. Beam sides can be deshuttered on next day of casting. As far as beam bottom is concerned, same can be deshuttered only after testing the cubes in 15 days and required strength is achieved. For beam span more than 6m, deshuttering can be done after 21 days only.

47. Picture showing wrong placement of beams dowels from the column, which shall be avoided on sites. Reinforcement has shifted towards one side of column.

Curing.

Curing shall be continued for beams sides also ( if beam sides are deshuttered) till 7 days after casting. Normally date of slab casting is written on beam sides for keeping track of curing period.

beam hand book

Documents