A domain decomposition approach for coupled modelling of nonlinear soil–structure interaction

This paper proposes a new approach for modelling coupled nonlinear soil–structure interaction problems by domain decomposition. It is assumed that the soil–structure coupled system is physically partitioned into independently modelled soil and structure sub-domains. A coupling procedure based on the sequential iterative Dirichlet–Neumann coupling algorithm is presented, which utilizes the condensed tangent stiffness matrices at the soil–structure interface to ensure and accelerate convergence to compatibility in successive update of the boundary conditions. As a special case of the proposed approach, the condensed tangent stiffness matrix is approximated via reduced order models of the partitioned sub-domains throughout the coupling iterations. A simulation environment has been developed, utilizing discipline-oriented solvers for nonlinear structural and geotechnical analysis, and is discussed. This tool is used to demonstrate the applicability of the presented coupling algorithm in modelling nonlinear soil–structure interaction problems, highlighting its relative merits compared to interface relaxation algorithms. Furthermore, the developed tool is employed for a case study involving nonlinear soil–structure interaction analysis between a plane frame and soil subjected to ground excavation, where the computational and modelling benefits of the proposed approach and the developed tool are clearly established.