Question

Which of the following is true about torsional buckling?

(a) failure occurs by bending about shear centre in longitudinal axis

(b) failure occurs when torsional rigidity of member is greater than bending rigidity

(c) standard hot rolled shapes are not susceptible to torsional buckling

(d) it cannot occur with doubly symmetric cross section

The question was posed to me in class test.

The origin of the question is Behaviour and Ultimate Strength of Plates and Possible Failure Modes topic in section Plastic and Local Buckling Behaviour of Steel of Design of Steel Structures

Answer 1

Correct choice is (c) standard hot rolled shapes are not susceptible to torsional buckling

The best I can explain: In torsional buckling, failure occurs by twisting about shear centre in longitudinal axis. It occurs when torsional rigidity of member is appreciably smaller than bending rigidity. It can occur only with doubly symmetric cross section with very slender cross sectional elements. Standard hot rolled shapes are not susceptible to torsional buckling.