Question

A compact section of a laterally unsupported steel beam has an elastic section modulu, plastic section modulus and design bending compressive stress of 400 cm${}^3$, 600 cm${}^3$ and 200 MPa respectively. The design flexural capacity of the section is _________kN-m.

• A. 91
• B. 136.36
• C. 80
• D. 120

Answer 1

The correct option is D 120

Design flexural capacity of laterally unsupported beams is given by,

$M_d={\beta }_b{Z}_p\frac{f_y}{{\gamma }_{m0}}$

${\beta }_b=1.0\left(\text{for plastic and compact section}\right)$

$M_d=1.0\times 600\times {10}^3\times 200\times {10}^{-6}$
=120 kNm