$2-36*$ A steel bar with a butt$-$welded joint, as shown in Fig. P$2-$

$36,$ will be used to carry an axial tensile load of $400$ kN $.$ If the

normal and shear stresses on the plane of the butt weld must

be limited to $70$ MPa and $45$ MPa $,$ respectively, determine the

minimum thickness $t$ required for the bar.