Lateral Load-Sharing Response of Piled Raft Foundation Under Seismic Loading in Sandy Soil: Fid-Bau Portal

Lateral Load-Sharing Response of Piled Raft Foundation Under Seismic Loading in Sandy Soil

Sakshi / Chanda, Diptesh / Saha, Rajib

The combined piled raft foundation (CPRF) is globally embraced as an appropriate foundation system for sustaining high-rise superstructures because of the number of advantages offered such as load-sharing between the piles and the raft, a decrease in total and differential settlement, limiting the foundation's overall tilt, etc. The design of this foundation type heavily relies on its composite load-sharing mechanism between the piles and the raft element. Substantial research works were performed previously to comprehend the load-sharing effect of CPRF under static vertical and lateral loading. However, the evaluation of the load-sharing behaviour of CPRF under transient motions is relatively terse as it poses intricacy in defining the complex interaction between the soil-piled raft-superstructure system under dynamic loading conditions. The present study, therefore, attempts to report on the lateral load-sharing (LLS) behaviour of CPRF under seismic loading in sandy soil through 3D finite element numerical analysis in ABAQUS [Abaqus/CAE User’s Manual (2008)]. One long-period superstructure (i.e., T_fixed = 3.0 s) supported by CPRF and subjected to two different input motions, i.e., Chichi 1999 (PGA = 0.361 g) and Landers 1992 (PGA = 0.7803 g), respectively is considered for the present analysis. The study indicates that the LLS contribution of the pile increases with the rise in the duration of the input motions. The pile sustains a maximum of 28 and 14% of the total lateral load for the 1999 Chichi and 1992 Landers earthquakes, respectively. Thus, the study may help in framing constructive design principles on load-sharing responses of CPRF under dynamic loading.