Modeling of 1D wave propagation in nonlinear soils using the elasto-plastic Iwan model by four numerical schemes

The international project PRENOLIN is focused on verification and validation of numerical codes for ground motion simulations including nonlinear soil rheologies. In this particular study, we present implementations of the elasto-plastic Iwan model (Iwan, 1967) into numerical schemes based on finite-difference, finite element, spectral element and discontinuous Galerkin methods, and results based on test numerical simulations. We study the amplification of ground motion in a soft layer with nonlinear behavior overlying a halfspace with linear behavior. We assume a vertically incident plane SH wave with source-time function given by a Gabor wavelet. We include different amplitude levels and frequency ranges. Special attention is given to the hysteresis loops and the reversal points in the stress-strain plane, and their effects on the computed seismograms and corresponding transfer functions. We compare key aspects of the individual numerical schemes and methods, and their advantages and disadvantages.