Question

A steel column of ISHB 350 @72.4 kg/m is subjected to a factored axial compressive load of 2000 kN. The load is transferred to a concrete pedestal of grade M20 through square base plate. Consider the bearing strength of concrete as 0.45 f_ck, where f_ck is the characteristic strength of concrete. Using limit state method and neglecting the self-weight of base plate and steel column, the length of a side of the base plate to be provided is
1. 39 cm
2. 42 cm
3. 45 cm
4. 48 cm

Answer 1

Correct Answer - Option 4 : 48 cm

Concept:

Bearing plates are provided below the column to transfer the load to the concrete pedestal.

Area required for the base plate = Factored load / Bearing Capacity of concrete

Bearing Capacity of concrete = 0.45 × f_ck

f_ck - Characteristic strength of concrete

Calculation:

Given:

Factored load = 2000 kN, Bearing Capacity of concrete = 0.45 × 20 = 9

∴ Area required = 2000000/9 = 222222.222 mm²

Side of plate = √222222.222 = 471.40 mm = 47.1 cm

∴ A plate of 48 cm is to be provided.