Illustrate about the strap footing?

In given demonstrates figure the exterior footing placed eccentrically under the exterior column so that property line limitations are not violated. Non-uniform pressure distribution is produced under the footing. This may lead to footing rotation. To balance this rotational or over turning effect, the exterior footing is connected by a stiff beam or strap to the nearest interior footing and uniform soil pressures under the footings are assumed.

Strap Footing

The strap may be considered as a flexural member. It is subjected to both bending moment and shear resulting from the forces P_i, and Re acting on the exterior footing. The applied moment is counter clock wise and R_e will be greater than P_e. There is no eccentricity at the interior column between the column load P_e and the resultant soil pressure force Ri. Hence it is assumed that there will be no induced moment in the strap at the interior column.