Nonlinear soil-structure interaction in geotechnical seismic isolation: A two-stage DEM-Preisach formalism framework

This paper investigates the nonlinear soil–structure interaction (SSI) of structures protected by a Geotechnical Seismic Isolation (GSI) system using a novel two-stage methodology relying on a DEM-based Preisach formalism. In the first stage, the Distinct Element Method (DEM) is employed to evaluate the key mechanical properties governing foundation–soil interaction and to capture their inherent variability resulting from random particle distributions. In the second stage, the soil’s hysteretic behaviour is modelled using the Preisach formalism, with nonlinear springs and dashpots calibrated using the DEM results. The main novelty of the paper is the derivation of the reduced order SSI model from DEM simulations, which, in turn, require only soil data for calibration. Moreover, the proposed framework enables a comprehensive evaluation of GSI performance through extensive nonlinear numerical simulations that explicitly account for soil variability. A Monte Carlo simulation study is conducted to assess the probabilistic response of an idealized benchmark structure. Comparative analyses between SSI scenarios involving either a natural soil composed of a homogeneous gravel layer or a composite soil profile incorporating a rubber–soil mixture (RSM) demonstrate the flexibility of the proposed method and highlight the influence of RSM on the structural response.