Question

Critical bending moment capacity of a beam undergoing lateral torsional buckling is a function of

(a) does not depend on anything

(b) pure torsional resistance only

(c) warping torsional resistance only

(d) pure torsional resistance and warping torsional resistance

I got this question by my school teacher 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

The correct answer is:

(d) pure torsional resistance and warping torsional resistance

Explanation:

The critical bending moment capacity of a beam undergoing lateral torsional buckling (LTB) is influenced by both pure torsional resistance and warping torsional resistance. Lateral torsional buckling occurs when a beam is subjected to bending, and the combination of bending and twisting leads to instability.

• Pure torsional resistance refers to the beam's ability to resist twisting due to shear forces.
• Warping torsional resistance refers to the beam's ability to resist distortions or warping along its length, which is especially important in slender beams.

Both types of resistance contribute to the stability of the beam under bending and twisting, influencing the critical moment at which buckling occurs. Therefore, the critical bending moment capacity depends on both factors, making option (d) the correct answer.