Nonlinear soil-pile-structure interaction for structures resting on a 2 x 2 pile group under earthquake excitations

This paper summarizes a new continuum model for the nonlinear soil-pile-structure interaction under earthquake excitations. The earthquake excitation is modeled as a harmonic shear wave, and the soil is considered to compose of an inner nonlinear zone around the pile and an outer linear elastic zone. The pile-soil-pile interaction is considered by using a Winkler model with its spring constant estimated from the wave-interference. The difference of shaking for the coupled system and the free field may be up to three times when gimel is at the first natural frequency of the structure or at high frequency. There exists a critical ground shaking at which the seismic response is the largest. The response of pin-piled structures can either larger or smaller than that of Fixed-piled structures. In general, the interactions are highly dependent of the excitation frequency, the pile-to-pile distance, the amplitude of ground excitation, and the nonlinearity of soil.