How do you calculate the footing shear strength?
The concrete shear strength in one-way action is defined by the expression φVc = φ2√f’c bd, where b is the footing dimension under consideration. On the other hand, the punching shear strength depends of the column location on the footing, either interior, edge or corner, per the expression φVc = φ Min(2+4/β, αs d/bo+2, 4) √f’c, where β is the column aspect ratio and αs is the column location factor.
ASDIP FOUNDATION calculates the one-way shear and the punching shear as described above and compares them to the corresponding calculated shear strengths. The figure below shows the typical punching shear calculations reported by the program for the controlling load combination.