Some useful tips to work out the cutting Length of Bent Up Bar In Slab

For a site engineer, it is essential to work out the cutting length of bars based on the slab dimensions and provided instructions to the bar benders.

If the construction work is intended for the small area, the reinforcement detailing can be transferred to the bar benders. They will deal with the cutting length. But be careful that it may not be perfect as they do not consider the bends and cranks. They may provide some additional inches to the bars for the bends which are fully imperfect. Therefore, to get rid of this issue, a site engineer should try to compute calculate the cutting length independently.

In this article, detailed explanation is given for working out the length for reinforcement bars of slab.

The calculation is made on the following dimensions :-

Diameter of the bar = 12 mm
Clear Cover = 25 mm
Clear Span (L) = 8000
Slab Thickness = 200 mm
Development Length(Ld) = 40d

Process for computation

Cutting Length = Clear Span of Slab + (2 x Development Length) + (2 x inclined length) – (45° bend x 4) – (90° bend x 2)
Inclined length = D/(sin 45°) – dD/ (tan 45°) = (D/0.7071) – (D/1)= (1D – 0.7071D)/0.7071= 0.42 D
There exist four 45°bends at the inner side (1,2,3 & 4) and two 90° bends ( a,b ).
45 ° = 1d; 90 ° = 2d
Cutting Length = Clear Span of Slab + (2 X Ld) +(2 x 0.42D) – (1d x 4) – (2d x 2) [BBS Shape Codes]

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Published By
Rajib Dey
www.constructioncost.co
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Method Statement For Column

To retain perfect line & location of columns/walls, the starter/kicker should be provided for each column & the location of shear walls, column wall hould be marked on raft/slab top to place starter/kicker.

The following points should be remembered :-

1. Starters should be made of 100 mm x 50 mm channel section.
2. Concreting of starter should start once verification of layout with required clearance from clients.
3. Column wall shutters/boxes should be 12mm thick film coated ply containing backing angles at the edges and flat at the center about 300C/C both ways. The lift for columns should normally have 2.4 m height but it may change as per requirement.

4. Vertical reinforcement bars and Stirrups should be arranged according to drawings & BBS verified by clients and duly secured with binding wire.
5. The reinforcement bars should be retained in exact location firmly from sway with proper scaffolding arrangement.
6. There should be exact cover to the reinforcement with sufficient numbers of concrete cover blocks.
7. Column shutters should be constructed perfectly to line and plumb and there should be sufficient supports to retain the same in exact location during & after concreting.
8. There should be exact staged platform for concreting.

9. Concrete pour card should be formed depending on the sanctioned format and maintained for each pour duly signed by the client.
10. Columns have to be poured in layers of 300 mm thick and each layer is to be vibrated properly.
11. There should be sufficient numbers of skilled and unskilled manpower to take delivery of the concrete.
12. In night work, there should be perfect arrangements for lighting.
13. Construction and expansion joints should be arranged and treated as per instructions/specifications.

14. Any loose deposited concrete should be eliminated & discharged.
15. Hessian cloth should be provided and covered around the column/wall for retaining the component soaked for at least of 14 days.

De-shuttering should be executed after 12 hours/24 hours upon completion of casting of individual pours according to technical requirements and codal provisions.

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Published By
Rajib Dey
www.constructioncost.co
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Details of slab reinforcement on the basis of bar bending schedule

This construction video provides detailed information on slab reinforcement that is created with bar bending schedule (BBS).

Slab reinforcement stands for the method that is undertaken to bend reinforcing steel and transform into shapes necessary for building up reinforced concrete structure.

Bar bending schedule (aka schedule of bars) belongs to a list of reinforcement bars, a specified RCC work item. It is demonstrated in a tabular form for smooth graphical reference.

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Published By

Rajib Dey

www.constructioncost.co

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