Seismic Analysis of Pile Group truss Foundation for Deep water Bridges

Abstract:

The frequencies and the modal hydrodynamic pressure of the parallel and nonparallel vibration modes for a submerged two pile system are investigated first. The results show that the nonparallel vibration of the two pile system increases the hydrodynamic effect. The pile group truss foundation is developed to control the nonparallel vibration of piles and increase the stiffness by installing the truss braces between piles. The modal tests for a typical group foundation and three developed pile group truss foundation designs are carried out on a 4 pile foundation specimen to investigate the dynamic performances experimentally. The seismic performance of the pile group truss foundation is then assessed through seismic response spectrum analyses of a four span deep water bridge. The study shows that the properly designed pile group truss foundation improves and optimizes the seismic responses of the deep water bridges.

Key words:deep water bridge; earthquake resistant of bridge; pile group truss foundation; modal testing; potential based fluid element