Question

The check for non- dimensional slenderness ratio is given by

(a) λLT =  2.4 √(Zefy/Mcr)

(b) λLT > 2 .4 √(Zefy/Mcr)

(c) λLT ≤ 1.2 √(Zefy/Mcr)

(d) λLT ≥ 1.2 √(Zefy/Mcr)

This question was posed to me during an interview.

Asked question is from Design Strength of Laterally Unsupported Beams topic in chapter Design of Beams of Design of Steel Structures

Answer 1

Right option is (c) λLT ≤ 1.2 √(Zefy/Mcr)

To explain I would say: The non- dimensional slenderness ratio is given by λLT = √(βbZpfy/Mcr). The check for it is given by λLT ≤ 1.2 √(Zefy/Mcr), where Ze = elastic section modulus, Mcr  is elastic critical moment.