Question

The properties of the section of a laterally supported beam is shown in figure:The section is plastic. Design bending strength (in kN-m) of the beam is______. $f_y=250MPa$

• A. 155

Answer 1

The correct option is A 155
As the section is plastic and laterally simply supported
$M_d=\frac{{\beta }_b{z}_p{f}_y}{{\gamma }_{m0}}\le \frac{1.2z_e{f}_y}{{\gamma }_{m0}}$
$\frac{{\beta }_b{z}_p{f}_y}{{\gamma }_{m0}}=\frac{1\times 750\times {10}^3\times 250}{1.1}=170.45kN-m$
$\frac{1.2z_e{f}_y}{{\gamma }_{m0}}=\frac{1.2\times 570\times {10}^3\times 250}{1.1}=155.45kN-m$
$\therefore$ Design bending strength $=155.45kN-m$