Three-dimensional dynamic soil-structure interaction analysis in the time domain

A new numerical procedure is proposed for the analysis of three-dimensional dynamic soil-structure interaction in the time domain. In this study, the soil is modelled as a linear elastic solid, however, the methods developed can be adapted to include the effects of soil non-linearities and hystereti c damping in the soil. A substructure method, in which the unbounded soil i s modelled by the scaled boundary finite-element method, is used and the st ructure is modelled by 8-21 variable-number-node three-dimensional isoparam etric or subparametric hexahedral curvilinear elements. Approximations in b oth time and space, which lead to efficient schemes for calculation of the acceleration unit-impulse response matrix, are proposed for the scaled boun dary finite-element method resulting in significant reduction in computatio nal effort with little loss of accuracy. The approximations also lead to a very efficient scheme for evaluation of convolution integrals in the calcul ation of soil-structure interaction forces, The approximations proposed in this paper are also applicable to the boundary element method. These approx imations result in an improvement over current methods. A three-dimensional Dynamic Soil-Structure Interaction Analysis program (DSSIA-3D) is develope d, and seismic excitations (S-waves, P-waves, and surface waves) and extern ally applied transient loadings can be considered in analysis. The computer program developed can be used in the analysis of three-dimensional dynamic soil-structure interaction as well as in the analysis of wave scattering a nd diffraction by three-dimensional surface irregularities. The scattering and diffraction of seismic waves (P-, S-, and Rayleigh waves) by various th ree-dimensional surface irregularities are studied in detail, and the numer ical results obtained are in good agreement with those given by other autho rs. Numerical studies show that the new procedure is suitable and very effi cient for problems which involve low frequencies of interest for earthquake engineering. Copyright (C) 1999 John Wiley & Sons Ltd.