Nonlinear 3D finite element analysis of soil–pile–structure interaction system subjected to horizontal earthquake excitation

• Equivalent linear soil model in three-dimensional analysis is proposed and validated.
• Nonlinear 3D finite element method is proposed for SSPSI response analysis.
• Effects of soil nonlinearity and soil dilation are investigated.
• Obvious separation and closing at the nonlinear soil–pile interface is observed.
• The presence of piles reduces the displacement response of soil and structure.

The dynamic response of a seismic soil–pile–structure interaction (SSPSI) system is investigated in this paper by conducting nonlinear 3D finite element numerical simulations. Nonlinear behaviors such as non-reflecting boundary condition and soil–pile–structure interaction modeled by the penalty method have been taken into account. An equivalent linear model developed from the ground response analysis and the modified Drucker–Prager model are separately used for soil ground. A comparison of the two models shows that the equivalent linear soil model results in an underestimated acceleration response of the structure under this ground shaking and the soil behavior should be considered as a fully-nonlinear constitutive model in the design process of the SSPSI system. It was also observed that the dynamic response of the system is greatly affected by the nonlinearity of soil–pile interface and is not sensitive to the dilation angle of the soil. Furthermore, the effect of the presence of pile foundations on SSPSI response is also analyzed and discussed.