Soil-structure interaction using BEM–FEM coupling through ANSYS software package

• BEM modeling of a far-field soil region subjected to seismic load.
• Dynamic condensation with DOFs reduction at the soil-structure contact zone.
• Conversion of the BE model of the infinite soil media in a single macro-element.
• Finite element modeling of a near-field soil and structure in ANSYS environment.
• Importing macro-element in ANSYS and coupling it with finite element model.

The main aim of this work is to develop, verify and apply in simulation study an efficient hybrid approach to study seismic response of a soil-structure system taking into account all the important components as: (1) the line time-harmonic source with its specific geophysical properties; (2) the inhomogeneity and heterogeneity of the wave path from the source to the local geological region; (3) the geotechnical properties of the near-field local geological profile and finally (4) the properties of the engineering structure itself. Plane strain state is considered. The hybrid computational tool is based on the boundary element method (BEM1) for modeling the infinite far-field geological media and finite element method (FEM2) for treating the dynamic behavior of the structure and the near-field finite soil geological region. Each of the two techniques is applied in that part of the whole model where it works more efficiently. The hybrid numerical scheme is realized via the sub-structure approach, direct BEM1, conventional FEM2 and insertion of the BEM1 model of the seismically active far-field geological media as a macro-finite element (MFE3) in the FEM2 commercial program ANSYS. The accuracy and verification study of the proposed method is presented by solution of numerical test examples simulating different seismic scenarios. The obtained results show clearly that the hybrid model is able to demonstrate the sensitivity of the synthetic signals to the source properties, to the heterogeneous character of the wave path, to the relief peculiarities of the local layered geological deposit and to the specific properties of the engineering structure.