Seismic Behaviour of RC Framed Building Supported on Combined Piled Raft Foundation in Sandy Soil

Abstract

Seismic design of combined piled raft foundation (CPRF) supported superstructure assumes fixed-base conditions but failures of pile group-supported structures during past seismic events unfolded the significance of seismic soil-structure interaction (SSSI). The current investigation is centred on unveiling the seismic behaviour of CPRF-supported superstructure embedded in sand incorporating the complex SSSI through a nonlinear three-dimensional finite element based numerical analysis. First, the efficacy of the developed model is verified. Thereafter dynamic analysis is performed considering past recorded seven different short, medium, and long-duration earthquakes and encompassing parametric variations of the superstructure and CPRF. Primarily, this study presents closed-form empirical relationships based on regression analysis to predict the maximum acceleration response of CPRF-supported multistorey buildings in sand. Further, the effect of complex SSSI on design responses, such as storey displacement and pile bending moment, is studied considering the impact of several controlling design parameters. The findings of the study suggest that acceleration and displacement response at various periods of superstructures are affected by the inclusion of soil flexibility. The peak acceleration is amplified as the waves pass through soil, piled raft, and superstructures. At last, the seismic design concepts obtained from this study are illustrated through a case study problem. � King Fahd University of Petroleum & Minerals 2024.