ABSTRACT
This paper presents the results of a numerical study evaluating the hydrodynamic response of two coastal bridges including the flexibility of the substructure, accounting for effects of fluid-structure interaction. The finite element model consists of a concrete girder bridge superstructure and multiple pier substructure, and it was developed using the commercial software Abaqus. The Coupled Eulerian-Lagrangian analysis technique was used to model the interaction between water and the bridge as the structure deformed due to wave impact. Wave velocity, frequency, and elevation were varied in the simulations to determine their effect on the dynamic response of the bridge, and in particular, on the maximum demands generated at the substructure-superstructure connections. It was found that the resultant shear and uplift forces increase with wave velocity, and that the calculated shear values were sensitive to the flexibility of the substructure. A comparison between connections forces calculated with the FEA model and the FHWA equations is presented. The peak uplift force was similar to the force calculated with the AASHTO design guidelines, and considerably higher than the self weight of the bridge, which implies a significant potential for uplift. Computed uplift force in the front deck was significantly higher than in the rear deck. The maximum uplift force for the model with flexible substructure was significantly lower than maximum computed force for the model with rigid supports). Horizontal forces were significantly higher than those calculated with the AASHTO guidelines, both in the front and rear decks. The horizonal force at impact from the second wave was significantly lower for the model with flexible supports, approximately 50% of the force computed with the model with rigid supports.
