Example $1$

A thin$-$walled step$-$like cross$-$section is shown in the figure. The structure is subjected to a bending moment applied along both the $x-$axis and $y-$axis.

$1-$ If a bending moment of $-60$ kNm is applied along the x $-$axis, and $12$ kNm along the y axis, calculate the resulting normal stresses at points $A,B,C,$ and D