Question

Multi-span beams collapse in one span as ___________

(a) does not collapse

(b) single-bar mechanism

(c) two-bar mechanism

(d) three-bar mechanism

The question was posed to me during an internship interview.

I'm obligated to ask this question of Plastic-Collapse Load topic in chapter Plastic and Local Buckling Behaviour of Steel of Design of Steel Structures

Answer 1

The correct option is (c) two-bar mechanism

To explain I would say: Multi-span beams generally collapse in one span as a local two-bar mechanism, within the span and a hinge at each support. It is possible to have a three-bar mechanism, where two adjacent spans combine to form a mechanism.