Nonlinear Rocking Stiffness of Combined Piled Raft Foundation

Rocking behavior of foundation during seismic excitation was recognized as an influencing mode of vibration on the dynamic response of structural system. Past research presented impedance expression for shallow and pile foundation considering rocking mode of vibration. Past proposals are found to be limited to linear stiffness. In this context, the present study attempts to propose nonlinear dynamic rocking stiffness of combined piled raft foundation (CPRF) in non-dimensional form by performing three-dimensional (3D) finite element analysis using PLAXIS 3D (Computer software, [28]). Nonlinear response of foundation is a well-evidenced phenomenon during moderate to strong earthquake excitation, and hence the incorporation of nonlinear impedance of foundation in sub-structure-based dynamic soil–structure interaction (DSSI) analysis is required to assess accurately the seismic response of superstructure and foundation. On the other hand, 3D seismic analysis of CPRF supported structure is relatively complex and computationally expensive. Hence, the outcome of the present study will offer a simplified solution to carry out seismic analysis of structure supported on CPRF and to frame design guideline for CPRF system.