Problem $2.$Use AcI$-318$

A beam cross has effective depth of $20$ in and web width of $10$ in$.$ The factored ultimate shear force at the critical cross section near the support is $56$ kip $.f_c^{\text{'}}=4500,f_{yt}=40,000.$

$($a$)$ Prove that shear reinforcement is required at the section.

$($b$)$ Calculate the spacing of No$.3$ double$-$legged stirrups.

$($c$)$ Check with the maximum spacing requirements.