Problem $4.$ For the beam shown determine the spacing of No$.4$ stirrups, and show the shear strength provided. The geometry of the beam is shown below. The loads given below are in addition to the beam weight $($assume $b=18$ in$.,h=22in.,$ and $d=19\mathrm{.}5$ in$.).$

$f_c^{\text{'}}=5000f_y=60,000$

$P_L=6$kips,$w_D=2$kip$\frac{s}{f}t,w_L=3\mathrm{.}0$kip$\frac{s}{f}t$