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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How to determine the cutting length of chair bar in slab & footings

The chairs in reinforcement are provided for the following reasons.

1. It retains the gap among the two bars as well as upper and lower cage reinforcement.
2. It provides strong supports to the bars.
3. It improves the strength of the structure and retains the tension in RCC.
4. It raises the tension property of concrete.
5. It reduces the scope for collapsing of the building because of the failure of compression and tension zone.

6. While vibrating, it holds the upper cage bar from collapsing.
7. The diameter of the bar should not be lower than 12 mm.

The chair bars should be made of the scraps in the jobsite.

In this civil engineering article, detail information is given for finding out the cutting length of chair bar in slab and footings.

The height is treated as the most crucial part of any chair as when the height is known, it becomes easier to determine the leg and the length of head.

The height of the chair bar will be determined with the following formula :-
Height = Height of footing – (2 x clear cover) – (dia of bottom main bar) – (dia of top main bar + dia of top distribution bar)

The head of the chair bar will be determined with the following formula :-
Head = (2 x spacing of top distribution bar) + 100

The leg of the chair bar will be determined with the following formula :-
Leg = (2 x spacing of bottom main bar) + 50

To learn the detail calculation process, go through the following video tutorial.

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Published By
Rajib Dey
www.constructioncost.co
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How to work out cutting length for column circular stirrups

This construction video is recorded to provide you some useful tips for estimating the cutting length of the circular column stirrups.

Here the radius of the column is taken as 400 mm.

Dia of stirrup is taken as 8 mm

Concrete Cover is taken as 40 mm

Stirrups are also known as Links or Rings or Transverse Reinforcement. Stirrups are applied in Beams and Columns. The stirrups remain vertical in a beam and horizontal in a column.

Benefits of column stirrups :
To settle and withstand the longitudinal (main) steel bars in columns to bulging below the vertical forces (compression force) particularly in the middle of the column prior to get to the concrete.

Increase the quantities (diameter or by spacing) of stirrups at both ends of the column with the intension of combating the horizontal forces which produce horizontal shear forces on both ends of the column.

Go through the following video, to get the detailed process.

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Published By
Rajib Dey
www.constructioncost.co
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