Expansion of the lumped parameter method to nonlinear, soil-structure interacting dynamic systems by means of a multi-objective optimization algorithm

Abstract

The computational demand of the soil-structure interaction (SSI) analysis for the design and assessment of structures as well as for the evaluation of life cycle cost and risk exposure has led the civil engineering community to the development of a variety of methods towards the model order reduction of the coupled soil-structure dynamic system. Different approaches have been proposed in the past as computationally efficient alternatives to the conventional FEM simulation of the complete structure-soil domain, such as the nonlinear lumped spring, the macroelement method and the substructure partition method. Yet, with few exceptions, no approach was capable of capturing simultaneously the frequency-dependent dynamic properties along with the nonlinear behavior of the condensed segment of the overall soil-structure system, thus generating an imbalance between the modeling refinement achieved for the soil and the structure. To this end, a dual frequency- and intensity-dependent expansion of the Lumped Parameter Modeling method is proposed in the current paper, materialized through a multi-objective algorithm, capable of closely approximating the behavior of the nonlinear dynamic system of the condensed segment. The efficiency of the proposed approach is validated for the case of an existing bridge, wherein the seismic response is comparatively assessed for both the proposed method and the detailed finite element model. The above expansion is deemed a computational efficient and reliable approach for simultaneously considering the frequency and amplitude dependence of soil-foundation-superstructure effects in the framework of nonlinear response history analysis.