Numerical modeling of seismic soil-pile-structure interaction (SSPSI) effects on tall buildings with pile mat foundation

Abstract

This research investigates the seismic soil-pile-structure interaction (SSPSI) effects on a tall building supported by a pile-mat foundation in Dhaka soil using nonlinear time-history analysis. A comparison between fixed base and flexible base models is conducted to analyze key design parameters including lateral displacements, inter-story drifts, foundation rotation, natural frequencies, and response spectra. The study focuses on a specific soil profile (Soil profile-1) in Dhaka, comprising cohesive and non-cohesive soil layers. A 42-story structure with four basements, situated on Dhaka soil, is modeled using finite element analysis with Midas GTS NX software. Results reveal that the settlement of the mat foundation exceeds permissible limits for tall buildings supported by a cohesive layer of Dhaka soil, advocating for the practicality and cost-effectiveness of a mat on piling foundation in such scenarios. Dynamic soil-structure interaction analysis demonstrates that although the flexible base model exhibits larger lateral displacement and inter-story drift compared to the fixed base model, these values remain within acceptable limits. Nominal foundation rotation is observed in the mat on pile foundation for Dhaka soil. The study concludes that employing a pile-mat foundation while neglecting soft soil does not significantly alter the analysis for tall buildings with multiple basements in Dhaka, validating the importance of considering SSPSI effects in structural design and analysis.