Question

What is lateral torsional buckling?

(a) buckling of beam loaded in plane of its weak axis and buckling about its stronger axis accompanied by twisting

(b) buckling of beam loaded in plane of its strong axis and buckling about its weaker axis accompanied by twisting

(c) buckling of beam loaded in plane of its strong axis and buckling about its weaker axis and not accompanied by twisting

(d) buckling of beam loaded in plane of its weak axis and buckling about its stronger axis and not accompanied by twisting

I got this question by my college professor while I was bunking the class.

Question is taken from Lateral Torsional Buckling in section Design of Beams of Design of Steel Structures

Answer 1

Correct option is (b) buckling of beam loaded in plane of its strong axis and buckling about its weaker axis accompanied by twisting

For explanation I would say: The buckling of beam loaded in plane of its strong axis and buckling about its weaker axis accompanied by twisting (torsion) is called as torsional buckling. The load at which such beam buckles can be much less than that causing full moment capacity to develop.