Question

Imperfection factor for rolled section is

(a) 0.1

(b) 0.21

(c) 2.1

(d) 4.9

This question was posed to me in a national level competition.

My query is from Design Strength of Laterally Unsupported Beams in chapter Design of Beams of Design of Steel Structures

Answer 1

The correct option is (b) 0.21

The explanation is: Imperfection factor for rolled section is 0.21. The imperfection factor takes into account all the relevant defects in real structure when considering buckling, geometric imperfections, eccentricity of applied loads and residual stresses. It depends on the buckling curve.