Question

A steel beam (with a constant El and span L) is fixed at both ends and carries a uniformly distributed load (w kN/m), which is gradually increased till the beam reaches the stage of Plastic collapse (refer to the following figure). Assuming 'B' to be at mid-span, which of the following is true.

• A. Hinges are formed at A and C only
• B. Hinges are formed at A and C together and then at B
• C. Hinges are formed at A, B and C together
• D. Hinges are formed at B and then at A and C together

Answer 1

The correct option is B Hinges are formed at A and C together and then at B


$B.M_{support}>B.M_{midspan}$

Therefore, as the load will increase plastic hinges will form first at support and then at midspan.

Therefore, option (c) is correct.