The factored two-way shear to be resisted by the pile cap is outlined in Two-Way Shear Capacity .

For cases of footings whose thicknesses are small in relation to their plan dimensions, the critical section used to calculate beam shear is taken as d/2 from face of column. The shear force is taken as the sum of the forces acting in all piles that lie outside a critical perimeter d/2 from the face of the column, for all load combinations under consideration. For a detailed description of the calculation of the concrete shear capacity please refer to Beam Shear Capacity .

When the punching shear critical section is outside of pile cap the punching shear will need to be checked using the supported column perimeter as the critical section. In this situation the ACI 318 code does not provide any guidance on calculating the concrete punching shear capacity so the CRSI 02 Design Handbook is used.

Concrete punching shear capacity per CRSI Eq 13-1:

When 0 < w < d/2 use linear interpolation.

When w > d/2 the usual punching shear capacity can be calculated per Section 4.5.3