A rectangular beam is $16$ in $.$ wide and has an effective depth of $26\mathrm{.}5$ in $.$ For $f_e^{\text{'}}=4000$ and $f_{ye}=60,000$ psi, determine the required spacing of No$.4$ stirrups for a factored shear of $90$ kips $.$ You can use the spreadsheet if you want but you don't need to$.$ Just follow these steps $($also in the shear design flowchart$)$: $(20$ points$)$

a$.$ Determine the contribution of concrete to the shear strength of the section.

This is $V_c=2v{f}_c^{\text{'}}bd.V_c=2v{f}_c^{\text{'}}bd$

b$.$ If no shear reinforcement is needed

c$.$ If $V_u>V_c{V}_s=\frac{V_v}{}{V}_c{A}_{ws}{f}_{yt}(\frac{d}{s})=V_s\frac{V_d}{2},$ minimum shear reinforcement $is$ required $(maximum$ spacing$)$

$d.If{V}_u>V_c,$ calculate the spacing $5of$ shear reinforcement using $V_s=\frac{V_v}{}{V}_c$ and $A_{ws}{f}_{yt}(\frac{d}{s})=V_s$