# How to calculate cutting length of bent up Bar(crank bar)

How to calculate cutting length of bent up Bar or crank bar,Cutting length of bent up Bar ( crank bar ),in this topic we know about how to calculate cutting length of crank bar and what is cutting length of bent Up Bar.

We know that bent up bar is also known as Crank that is used as main reinforcement in casting of roof slab, it is provided at bottom of slab in shorter span of slab.

Its main function to transfer the dead and live load of slab to the Beem and from Beam to column and beam transfer its load to foundation and footing and footing transfer into the bed of soil.

## what is cutting length?

length of Steel which is provided in slab and cut into desire length according to requirement of design of slab is known as cutting length.

### how to calculate cutting length of bent up Bar (crank bar)

Suppose we have given following measurement

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Note:- in this figure bent Up Bar or Main reinforcement and crank bar bend in both direction but some BBS of slab it is bend in one direction.

Diameter of bent Up Bar d=10mm

Thickness of slab= 150 mm

Clear span =4000 mm

Clear cover top and bottom=25 mm

Development length Ld=40d

Bend angle 45° = 1d

Bend angle 90°=2d

Cutting length= clear span+development length+inclined length_ bend elongation

1) clear span = 4000mm

2) development length

We have to development length in two sides of column which will be provided in beam

Development length=2Ld

Where Ld =40d is given

Developmental length= 2×40×10=800mm

3) inclined length =0.42H

We have to inclind length of bent Up Bar in both sides so total incline length is equal to

Inclined length= 2×0.42×H

Height= slab thickness_2C(cover at top and bottom)_diameter of bar

H=150_2×25_10= 90mm

Inclined length=2×0.42×90=75.6mm

4) bend elongation

In given diagram we have 4 band of 45 degree angle and two bend of 90 degree angle for 45 degree we have 1d and for 90 degree we have 2d where d is diameter of main reinforcement.

Bend=4 bend of 45°+2 bend of 90°

Bend= 4×1d +2×2d

Bend elongation=8d=8×10=80mm

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5) cutting length calculation

Cutting length= clear span+development length+inclined length_ bend elongation

CL=(4000mm+800+75.6)_80 mm

CL= 4875.6 _80mm

Hence cutting length=4795.6 mm

Cutting length of bent Up Bar=4.7956 meter