Hybrid computational framework for nonlinear soil-structure interaction under seismic excitation using subdomain decomposition

This study focuses on soil-structure interaction (SSI) under seismic excitation, using a direct hybrid method. During an earthquake, repeated impacts between the soil and the foundation lead to nonlinear dynamic behavior. In this context, a new subdomain coupling method is proposed to treat the contact between the soil integrated in time using a central difference scheme, and the concrete foundation integrated using the Newmark implicit scheme. The approach is implemented and validated in MATLAB through two illustrative applications. First, a one-dimensional benchmark problem involving two bars in contact demonstrates that the formulation accurately reproduces displacements, velocities, and contact forces in excellent agreement with a full explicit algorithm. Then, a two-dimensional case study of soil-concrete foundation interaction subjected to gravity loading highlights reduced computational time compared with the full explicit method. This work pro-vides a robust and efficient framework for simulating nonlinear SSI problems in the time domain.