Question

Which of the following relation is correct?

(a) λLT = √(fy/fcr,b)

(b) λLT = fy/fcr,b

(c) λLT = (fy/fcr,b)^2

(d) λLT = √(fy fcr,b)

This question was addressed to me in an interview for internship.

My doubt is from Design Strength of Laterally Unsupported Beams in portion Design of Beams of Design of Steel Structures

Answer 1

Correct answer is (a) λLT = √(fy/fcr,b)

Easy explanation: λLT = √(βbZpfy/Mcr) = √(fy/fcr,b), where βb  = 1 for plastic and compact sections, βb  = Ze/Zp for semi-compact sections, Ze = elastic section modulus, Zp = plastic section modulus, Mcr  is elastic critical moment, fcr,b is extreme compressive elastic buckling stress.