Check One-Way Deep Beam Shear

By inspection, the major direction of footing will be critical.

w = \frac{36}{2} - \frac{20}{2} + 3 = 11 "

V_u = 6(160) - 0.9(29.8) = 933 kips

M_{u} = 160 [3 (54 + 3 - \frac{20}{2}) + 3 (18 + 3 - \frac{20}{2})] - 0.9 (29.8) (\frac{59}{2}) = 28, 094 kip-in = 2, 258 kip-ft

\frac{w}{d} = \frac{11}{47.4} = 0.24 < 1.0

Thus we use Eq. 13-2 of CRSI 13-16,

v_{c} = (\frac{d}{w}) [3.5 - 2.5 (\frac{M_{u}}{V_{u} d})] [1.9 \sqrt{{f^{'}}_{c}} + 0.1 \sqrt{{f^{'}}_{c}} (\frac{V_{u} d}{M_{u}})] \leq 10 \sqrt{{f^{'}}_{c}}

v_{c} = \min {\begin{matrix} (\frac{47.4}{11}) [3.5 - 2.5 (\frac{27, 094}{933 \cdot 47.4})] \times [1.9 \sqrt{3, 000} + 0.1 \sqrt{3, 000} (\frac{933 \cdot 47.4}{27, 094})] \\ 10 \sqrt{3, 000} Controls \end{matrix}

v_c = 547.7 psi

ϕV_n = 0.75(547.7)(102)(47.4) = 1,986 kips