Problem $3.$

A beam cross has effective depth of $18$ in and web width of $9$ in $.$ The factored ultimate shear force at the critical cross section near the support is $50$ kip $.$

$f_c^{\text{'}}=4500,f_{yt}=40,000$

$($a$)$ Determine whether web shear reinforcement is required at the section. If it is required, determine the spacing of No$.3$ double$-$legged stirrups.

$($b$)$ What is the allowable maximum spacing for the cross section?