Earthquake response analysis in the time domain for 2D soil-structure systems using analytical frequency-dependent infinite elements

This paper presents a time domain method for soil–structure interaction analysis under seismic excitations. It is based on the nite element formulation incorporating analytical frequency-dependent in nite elements for the far- eld soil region. Equivalent earthquake input forces are calculated based on the free- eld responses along the interface between the near- and far- eld soil regions using the xed exterior boundary method in the frequency domain. Then, the input forces are transformed into the time domain by using inverse Fourier transform. The dynamic sti ness matrices of the far- eld soil region formulated using the analytical frequency-dependent in nite elements in the frequency domain can be easily transformed into the corresponding matrices in the time domain. Hence, the response can be analytically computed in the time domain. A recursive procedure is proposed to compute the interaction forces along the interface and the responses of the soil–structure system in the time domain. Earthquake response analyses have been carried out on a multi-layered half-space and a tunnel embedded in a layered half-space, and results are compared with those obtained by the conventional method in the frequency domain