$($c$)$ An approximation to one panel of profiled steel sheeting is shown in Figure Q$2.$ The sheet is $1\mathrm{.}2$ mm thick and the design yreld strength is $280\frac{N}{m}{m}^2.$ It is to be used to resist a sagging bending moment. It can be assumed that the web is fully effective in resisting bending.

Points to note:

Stiffener shown above is located at the middle of the plate;

It should be assumed that the stiffener is effective in preventing buckling at the middle of the plate but otherwise it should be neglected when deriving the resistance;

As the steel sheeting is relatively thin, calculations can be based on overall dimensions as shown above.

Figure Q$2($Not to scale$).$

Evaluate the design moment of resistance $($Unit: $kN\frac{m}{m}).$

$[6$ marks$]$