Non-linear soil-structure interaction effect on the seismic response of a building

In presence of a non-linear soil behavior induced by a strong earthquake, the stiffness and damping characteristics of the soil as well as the dynamic response of the structure can be affected. Therefore, this work aims to study the influence of the non-linear soil behavior on the seismic response of the soil-structure system with a new approach using the Caldynasoil computational code based on equivalent-linear method. Using the analytic method, the seismic response of the selected structure was obtained for a nonlinear soil behavior and for two forms of impedance functions. Two types of analyses were performed: first, through an analytical formulation based on the dynamic equilibrium of the soil-structure system modeled by an analog model with three degrees of freedom, and then through a numerical analysis performed with 2D finite element modeling using Abaqus software. The results of the latter type of analysis were compared with those of the analytical solution for validate the obtained results in the first analysis. Finally, we propose new analytical nonlinear relationships between the displacements of the structure, the seismic acceleration level, and the excitation frequencies, taking into account the equivalent linear soil behavior. The change in soil behavior due to the imposed seismic motion in this work shows a significant effect on the response and displacement of the structure. This effect is characterized by an overestimation of the displacement of the structure and a strong dependence on the type of impedance function and soil properties. Excellent agreement between finite element analysis and analytical results was obtained due to the reasonable representation of the model.