Determine the maximum in$-$plane shear stress

in the box beam at point A and point $B.$ Show

the results on an element located at this

point.

Hints:

Note that you first need to determine internal

forces at a section passing through A and B $.$

Then, determine all stresses $($ and $)$ at this

section considering the cross section of the

beam.

$4in.\frac{1}{6in.}*\frac{13}{3}in.$

Draw an element with these stresses $($what are

${}_x,{}_y,{}_{xy}?)$

Use Mohr's circle to determine maximum shear stress.