Nonlinear dynamic analysis of framed structures including soil-structure interaction effects

The role of soil-structure interaction on seismic behavior of reinforced concrete structures is investigated in this paper. A finite element approach has been adopted to model the interaction system, that consists of the reinforced concrete plane frame, soil deposit, and interface which represents the frictional surface between foundation of the structure and subsoil. The analysis is based on the elasto-plastic behavior of the frame members (beams and columns) that is defined by the ultimate axial force-bending moment interaction curve, while the cap model is adopted to govern the elasto-plastic behavior of the soil material. Mohr-Coulomb failure law is used to determine the initiation of slippage at the interface, while the separation is assumed to occur when the stresses at the interface becomes tension stresses. Newmark's Predictor-Corrector algorithm is adopted for nonlinear dynamic analysis. The main aim of the present work is to evaluate the sensitivity of structures to different behaviors of the soil and interface layer when subjected to an earthquake excitation. Predicted results of the dynamic analysis of the interaction system indicate that the soil-structure interaction problem can have beneficial effects on the structural behavior when different soil models (elastic and elasto-plastic) and interface conditions (perfect bond and permitted slip) are considered.