Seismic response analysis of complicated soil-structure interaction using inelasticity-separated scaled boundary finite element method

Abstract

Inelastic seismic response analysis of large infrastructure needs to consider the soil-structure dynamic interaction with a reasonable absorbing boundary condition and generally requires refined simulation, which is an extremely complicated and time-consuming process. Because these structures are generally irregular, the use of a conventional finite element mesh for refined simulation makes the process of modelling pretreatment more complicated, and the corresponding computation scale is usually large. Although the development of computer hardware has greatly improved the computational efficiency of nonlinear problems, studies related to an efficient solving algorithm and appropriate element formulation that can achieve refined simulation, flexible mesh generation, and high precision for large-scale complex structures are still the focus of civil engineers. Because the material nonlinearity of a structure generally occurs in local regions, various emerging algorithms have been developed to accelerate the computation of inelastic response analyses based on various methods such as the reanalysis method and the inelasticity-separated finite element method (IS-FEM). The scaled boundary finite element method (SBFEM), which is a semi-analytical method, is known for its flexible meshing capability and high precision. The idea of inelasticity-separated is introduced into the SBFEM, and the viscous-spring artificial boundary is combined with a novel inelasticity-separated S-element formulation to propose a dynamic solution scheme that can solve the problems associated with element meshing and the nonlinearity of models with complicated soil-structure dynamic interaction. To implement the semi-analytical S-element for use in inelasticity-separated method, the Gaussian numerical integration scheme is performed for each subelement. The proposed dynamic solution scheme for soil-structure interaction is basically the same as that of a static problem and can also be solved by the efficient Woodbury approximation approach because a more inelastic strain interpolation point layout in the S-element leads to larger inelastic degrees of freedom (IDOFs). In this paper, not only the mesh flexibility and high precision of the SBFEM is retained but also the nonlinear solving efficiency is greatly improved without decreasing precision. Numerical examples demonstrate the validity and efficiency of the proposed inelasticity-separated S-element formulation and dynamic solution scheme.