Determination of Base Stresses in Rectangular Footings under Biaxial Bending †1

All the footings of buildings in seismic regions are to be designed according to biaxial bending moments. The purpose of this paper is to develop a general method for calculating the base pressures of rectangular footings under biaxial bending. First the footings which are exposed to large eccentricity are classified according to the shape of the pressure region. Then the formulation given by Loser for the design of rectangular columns subjected to biaxial bending are generalized and applied to the calculation of base stresses. Since the position of the neutral axis is not known initially, a process of successive approximations is developed. The application of the computation procedure is demonstrated on a numerical example.