Determine strap beam with suitable demonstration.

Here observe that R_e becomes greater than P_e by a magnitude of V while R_i becomes less than P_i by a magnitude equal to V. You can obtain the footing areas by dividing the reactions R_i and Re by net allowable soil pressures. These values are based on an assumed value of e and have to be recomputed until the trial e and actual e are the same.

Strap Beam

The interior footing is designed as an isolated column footing subjected to a load R_i. The exterior footing is considered as under one way transverse bending similar to a wall footing. The longitudinal steel is furnished by extending the strap steel into the footing. The selection of footing thickness and reinforcement should be based on factored loads consistent with IS code and Limit State Design Approach.

The strap beam is assumed to be a flexural member with no bearing on the soil underneath. The strap is designed as a rectangular beam subjected to a constant shearing force and a linearly varying negative bending moment.