The channel shape cross$-$section and the rectangular cross$-$section shown in the Figure Q$4$ are

made of materials with elastic$-$perfectly plastic behaviour. The yield stress of the material used for

the channel shape cross$-$section is ${}_y=418$MPa, whereas that used for the rectangular cross$-$

section is $0\mathrm{.}7{}_y.$

Compute the thickness of the web, $t,$ of the channel shape section if the two cross sections have

identical plastic bending moment about the z$-$axis.

In Figure $4,$ h$=84mm,b=46mm,a=11mm,H=84mm,d=46mm$

Part a$)$

The numerical value of plastic section modulus of the solid rectangular section is

$m{m}^3$

The numerical value of plastic moment of the solid rectangular section is

N$.$mm

Part b$)$ calculate the value of $t$

The numerical value of $t$ can be calculated as

$mm$