How to calculate Cutting length of rectangular stirrup in beams

Q:- Calculate the cutting length of the stirrups given in fig 1. Clear cover of beam is 25 mm & Diameter of stirrup is 8 mm

STIRRUPS
fig 1 : Cross section of beam

Ans:-

Given data:

Clear cover = 25 mm

Depth of beam = 450 mm

Width of beam = 300 mm

Diameter of stirrup =8 mm

Cutting length of stirrup = 2a+2b + (2 x Hook length) – Bend deduction

Where, 

a= Width of beam – (2 x clear cover) – ( 2 x Half of diameter of bar)

b= Depth of beam – (2 x clear cover) – ( 2 x Half of diameter of bar)

New Doc 2018-09-07 17.26.18_1

Therefore, 

a= 300 – (2 x 25) – (2 x 4) = 242 mm

b= 450 – (2 x 25) – (2 x 4) = 392 mm

Length of hook (Development length) = 10 d = 10×8 = 80 mm

 

Bend deductions: 

90 degree bent –> 3 no’s 

For 90 degree bend, length reinforced bar increase by 2 d

i.e., Bend length = 3 x (2×8) = 3×16 = 48 mm

135 degree bent –> 2 no’s 

For 135 degree bend, length reinforced bar increase by  3d

i.e., Bend length = 2 x (3×8) = 2 x 24 = 48 mm

∴ Cutting length of stirrup = (2×242) + (2×392) + (2×80) – (48+48) = 1428 – 96 = 1332 mm

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