The channel shape cross$-$section and the rectangular cross$-$section sFigure Q$4$hown 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 sigma y

$=488$ MPa, whereas that used for the rectangular cross$-$section is $0\mathrm{.}8$ sigma 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$=79$ mm$,$ b$=58$ mm $,$ a$=11$ mm $,$ H$=79$ mm $,$ d$=58$ mm

Figure Q$4$

Part a$)$

$1.$ The numerical value of plastic section modulus of the solid rectangular section is

mm$^3$

$2.$ The numerical value of plastic moment of the solid rectangular section is

N$.$mm

$8$ marksUnanswered

Part b$)$ calculate the value of t

The numerical value of t

can be calculated as

mm