Beam shear or one-way shear capacity is taken at a distance of from the column face or the reduced base plate edge. The value d is taken as the smaller of the reinforcement depth for the top and bottom flexure bars for the given direction.

The shear capacity is calculated using:

For light-weight concrete V_c is multiplied by 0.8 per BS8110: Part 2, Section 5.4. Also, the shear is checked at the face of the column to see if it is less then the lower of $0.8\sqrt{f_{cu}}$ or 5 N/mm². If it is, the concrete shear capacity is enhanced per BS8110: Part 1, Section 3.4.5.8 for the critical section at d( BS8110: Part 1, Section 3.4.5.10). The shear is also checked at 2d to make sure it is less then V_c calculated from BS8110: Part 1, Table 3.8.

In this case d is calculated from the footing clear cover and provided reinforcement diameter to give the effective depth. The flexure reinforcement parallel to the footing's larger dimension is taken to be the closest to the footing bottom. If the footing is a square then the reinforcement parallel to the major axis of the footing column is considered to be the closest to the footing bottom.

Due to the flexural reinforcement effect on the concrete shear capacity the shear check on the footing is performed after the flexural steel has been designed.

The ultimate applied shear V_u on the section is the total soil stress under the footing for the shear section under consideration. If there is any part of the critical shear area in tension, the program checks to see if the shear from the uplift portion of the footing using the footing slab self weight and surcharge controls the value of V_u.

Shear Check Critical Sections

Shear Check Critical Sections