Experimental and Numerical Assessment of the Three-Dimensional Modal Dynamic Response of Bridge Pile Foundations Submerged in Water

Abstract

This paper describes an experimental program conducted to investigate the effects of fluid-structure interaction on the modal dynamic response of three reduced-scale bridge pile foundations submerged partially or totally in water. The vibration periods of the specimens are measured for the two lateral modes and first torsional mode using ambient and forced vibration tests. The results are presented and discussed as a function of surrounding water levels and the number and geometrical patterns of the piles. Three-dimensional (3D) finite-element models of the tested specimens surrounded by different water levels are built, and the results are successfully validated against the obtained experimental data. The built numerical models are used to compute 3D modal hydrodynamic pressures. A systematic analysis of the period ratios and 3D hydrodynamic loads is presented to characterize the effects of pile cap, water height, and the number and geometrical pattern of the piles on dynamic response. The experimental and numerical results of this research allow a better understanding of the complex dynamically induced fluid-structure interaction effects in the response of deepwater bridge pile foundations.