Seismic Site Response of Nonlinear Soil Media

A complete procedure for the analysis of site response to earthquakes, assuming vertical, one-dimensional shear wave propagation, is presented. This entails the determination of low-amplitude soil moduli from in-situ shear-wave velocity measurements; the determination of the modulus/strain amplitude relationship for each soil type using free vibration torsion tests; the correction of these results for sample disturbance; and the determination of nonlinear soil parameters for use, finally, in a lumped-mass site response analysis. The use of a hysteretically damped nonlinear soil model in the analysis is described in some detail. Although limited by the constraints of the assumption of vertical, one-dimensional shear wave propagation, the method is believed to simulate actual soil profile behavior more closely than other models currently in use.