Question

The modulus of section required for angle section purlin is given by

(a) Z = M/(0.66xfy)

(b) Z = M/(1.33×0.66xfy)

(c) Z = M/(1.33×0.66xfy)

(d) Z = M/(1.33xfy)

I have been asked this question by my college director while I was bunking the class.

This question is from Purlins in section Design of Beams of Design of Steel Structures

Answer 1

Correct choice is (c) Z = M/(1.33×0.66xfy)

The explanation is: The modulus of section required for angle section purlin is given by Z = M/(1.33×0.66xfy), M = maximum bending moment = wl^2/10, w = unfactored uniformly distributed load, l = span of purlin, fy is yield stress. The gravity and wind loads are determined to calculate bending moment and both loads are assumed to be normal to roof truss.