1 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