Effect of coupling excess pore pressure and soil deformation on nonlinear SSI in liquefiable soil deposits

The current seismic design philosophy is based on nonlinear behavior of structures where the foundation soil is often simplified by a modification of the input acceleration depending on the expected site effects. The latter are generally limited to depend on the shear-wave velocity profile or a classification of the site. Findings presented in this work illustrate the importance of accounting for both soil nonlinearity due to seismic liquefaction and for soil-structure interaction when dealing with liquefiable soil deposits. This paper concerns the assessment of the effect of excess pore pressure (\(\Delta p_{w}\)) and deformation for the nonlinear response of liquefiable soils on the structure’s performance. For this purpose a coupled \(\Delta p_{w}\) and soil deformation (CPD) analysis is used to represent the soil behavior. A mechanical-equivalent fully drained decoupled (DPD) analysis is also performed. The differences between the analyses on different engineering demand parameters are evaluated. The results allow to identify and to quantify the differences between the analyses. Thus, it is possible to establish the situations for which the fully drained analysis might tend to overestimate or underestimate the structure’s demand.