A RCC column of size 400 × 400 mm has the longitudinal bars of 20 mm. What should be the pitch of lateral ties in this case?

A RCC column of size 400 × 400 mm has the longitudinal bars of 20 mm. What should be the pitch of lateral ties in this case? Correct Answer 300 mm

Concept:

As per IS 456:2000, clause 26.5.3.2 (c), 

Pitch:

The pitch of transverse reinforcement shall be not more than the least of the following distances:

1. the least lateral dimension of the compression members
2. 16 times the smallest diameter of the longitudinal reinforcement bar to be tied (i.e. 16 φmin)
3. 300 mm

The diameter of the Lateral Ties: 

The diameter of the lateral ties shall be not less than one-fourth of the diameter of the largest longitudinal bar and in no case less than 6 mm.

Calculations:

Given, 

B = 400 mm, ϕ = 20 mm

The pitch of transverse reinforcement shall be 

1. The least lateral dimension = 400 mm
2. 16 × 20 mm = 320 mm
3. 300 mm

whichever is smaller i.e. Minimum of ( 400 mm, 320 mm, 300 mm)

Hence, the pitch of lateral ties shall be kept as 300 mm.