ABSTRACT
Seismic performance of piled raft foundations (PRF) is crucial for stability of structures during earthquakes, especially under bi-directional ground motions. The seismic response of PRF is sensitive to incidence angle, which is often overlooked in conventional designs that assume alignment between structural axes and ground motion direction. This study addresses the impact of ground motion directionality on 15-storey reinforced concrete (RC) framed buildings supported on PRF embedded in sand by conducting series of finite element analyses (FEA) in SAP2000. Soil is modelled using API-based nonlinear p-y, t-z, and Q-z springs, and hysteretic behaviour is incorporated using Takeda model. The piles, beams and columns are modelled as frame elements, while raft and slabs are represented as shell elements in the FEA. Both symmetric and asymmetric pile layouts are considered. Results highlight significant variation in seismic demand due to directionality, highlighting the necessity of considering bidirectional effects in seismic design.
