Beam ABC is subjected to distributed load $(w_D$ and $w_L)$ and concentrated loads $(P_L$ and $M_L),$ as shown in Fig. $2.$ The beam supports a $6"$ thick concrete slab. Beam ABC is laterally braced at A and $B.$ If a W$18$x$86$ section is used, check the adequacy of the beam $AB.$ You may assume full composite action.

Given, for reinforced concrete slab, $f^{\text{'}}{?}^{\text{'}}=4,000,{}_{\text{I}}=0\mathrm{.}85.$