Question

Why is built up section used?

(a) to sustain seismic loads only

(b) for aesthetic appearance

(c) used when rolled section do not furnish required sectional area

(d) for resisting bending moment

The question was posed to me in an interview for job.

The question is from Elastic Buckling of Slender & Built-up Compression Members in portion Design of Compression Members of Design of Steel Structures

Answer 1

The correct answer is (c) used when rolled section do not furnish required sectional area

Easiest explanation: Size and shape of rolled sections are limited because of limitation of rolling mills. When rolled section do not furnish required sectional area or when special shape or large radius of gyration is required in two different direction, a built up section is used.