Nonlinear Torsional Dynamic Response of Footing

Abstract

A physical experiment was conducted in which dynamic torsional loadings were applied to a rigid circular model footing resting on a surcharged granular test bed. High amplitudes of strain, such as those encountered in large earthquakes, were developed. The torsional response of the footing and of selected locations within the test bed were measured. A newly developed numerical procedure, capable of solving the three‐dimensional axisymmetric nonlinear torsional wave equation, was used to simulate the experiment. The footing and test bed were modeled as a rigid disk resting on a nonlinear inelastic half space with slip permitted along the interface and on a linear elastic half space. Generally, experimental and nonlinear numerical results agreed well. It was concluded that to predict accurately the response of a soil‐foundation system when large shearing strains develop, nonlinear inelastic behavior of the soil must be taken into account. Also, it was concluded that the numerical procedure could predict accurately the response of the footing and reasonably well the response of the test bed.