Investigation on influence of slenderness ratio of piles on seismic response of building considering soil-structure interaction

Abstract

Pile foundations serve the purpose of transmitting structural loads from areas with low soil bearing capacity and stiffness to deeper soil or rock strata possessing greater bearing capacity and stiffness. The type and slenderness ratio (L/D) of the pile foundation, which supports mid-to-high-rise buildings, significantly influences the seismic response of the building during any seismic disturbance. The present paper investigates the influence of the slenderness ratio of piles on the seismic response of buildings through scaled-down model tests and numerical investigation. In this study, a scaled-down model featuring a 10-storey building and varying slenderness ratios (30, 40, and 50) for the pile foundation has been utilized. All the model tests are performed in the laminar shear box through shaking table tests, and the results obtained are validated using three-dimensional finite element analysis. All the models are subjected to sine sweep tests (for natural frequency prediction) and scaled-down input ground motions. The study has examined the seismic response of the building, which is characterized by the maximum lateral displacement, inter-storey drift, and the bending moment generated in the piles. It is found that the lateral displacement of the building supported on a pile foundation (L/D = 30) increases by 139.84% in comparison to fixed-base structures (FB). However, it is also found that the lateral displacement and inter-storey drift of the building supported on the pile (L/D = 50) have decreased by 10.79% and 21.48%, compared to those resting on piles with L/D = 30, respectively. Hence, it is concluded that the slenderness ratio of the pile foundation plays a significant role in the response of the building during seismic events.