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 deep water bridge pile foundations.

Effects of Dynamic Fluid-Structure Interaction on Seismic Response of Multi-Span Deep Water Bridges Using Fragility Function Method

“…The analytical solution of the added mass of water is exact but difficult for complex cases since many restrictive assumptions should be made. For this reason, Wei et al (2012) adopted the sophisticated 3D finite element models of the water-foundation system to demonstrate the effects of the fluid-structure interaction on pile foundations. Although the adequately modeled potential-based 3D elements could better assess 3D hydrodynamic load of structure, the computational time for one time-history analysis seems impractical for seismic fragility analysis or future risk assessments of different bridge classes.…”

“…The proposed procedure to account for seismic hydrodynamic effects of deep water group foundations is verified by comparing the calculated results from finite element models with available laboratory tests (Wei et al 2012). The reduced-scale bridge pile foundations were tested for different water levels to investigate the effects of fluid-structure interaction on modal dynamic response.…”

“…The geometric scale of this model is 1/10. The detail descriptions of the modal test can be referred to the study (Wei et al 2012). The reduced tests only investigated deep water pile foundation rather than the whole bridge model.…”

Improvement on Structural Forms of Pile Group Foundations of Deepwater Bridges

“…e bridge foundation has a variety of forms such as the caisson foundation, the tube caisson foundation, and the open caisson foundation. When the water is deep, the pile foundation, which consists of a group of bored piles extending to soil at the bottom and connected to a large cap at the top, has widely been used owing to its convenient construction and good adaptability [24][25][26]. However, it is difficult to model the precise dynamic response of the pile foundation under various dynamic loads due to large dimensions, structural complexity, and three-dimensional characteristics [27].…”

Influences of Pile Group Effects on Wave Forces on an Offshore Bridge Pile-Cap Foundation

“…In recent years, pile foundations have been commonly used in deep-water long-span offshore bridge construction due to their low cost, convenient construction, and structural efficiency [1][2][3]. The pile-cap system commonly found in these large-scale offshore bridge engineering environment is built by a group of piles with a large-scale cap on top of them.…”