Seismic Analysis of Piled-Raft Foundations in Mid-Rise Buildings on Soft Soil

Abstract

The utilization of piled-raft foundations is prevalent in buildings constructed on soft soil to mitigate settlement and increase bearing capacity. Nevertheless, if dynamic loading is not suitably considered during the design phase, these foundations may fail. This investigation utilizes three-dimensional finite element analyses in OpenSees to explore the seismic behaviour of mid-rise buildings with piled-raft foundations founded on soft soil. The principal focus of this study is on the influence of soil-foundation-structure interactions (SFSIs) under earthquake loadings. For this purpose, the El-Centro 1979 earthquake was used as the base acceleration underneath the soil layer to simulate the seismic conditions. The study scrutinizes the influence of pile flexural rigidity and superstructure configuration (G + 2, G + 4, G + 7) on the responses of mid-rise buildings on piled-raft foundations under earthquake loading. The findings revealed that buildings with a higher number of floors exhibit larger inter-storey drift with consideration of SFSI. Additionally, an increase in pile flexural rigidity significantly diminishes lateral displacements and shear force during earthquake loading. This study highlights that the flexural rigidity of pile and superstructure configuration are two pivotal factors that determine the response of piled-raft foundations of mid-rise buildings under earthquake loading. Proper consideration of these factors during the design phase can help mitigate the risk of failure and improve the performance of buildings with piled-raft foundations founded in soft soil. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.