Abstract
The effectiveness of countermeasures to prevent the tsunami-induced motion of a bridge superstructure are investigated in terms of tsunami force acting on the superstructure using a three-dimensional coupled fluid-structure-sediment interaction model. Numerical results show that fairings attached to the side of the superstructure and fenders fixed beside the superstructure reduce the horizontal tsunami force acting on the superstructure regardless of the configuration of the fairings and the height of the fenders. In addition, the fairings with the surface facing upward result in an increase in the downward vertical tsunami force and accordingly an increase in the static friction force. From these results, it is suggested that the fairings with the surface facing upward would be an effective countermeasure to delay the initiation of the motion of the superstructure. In contrast, the fairings with the surface facing downward reduce the static friction force, and accordingly the motion of the superstructure begins earlier than that for no fairing. The fenders also reduce the static friction force regardless of the height of the fenders. However, the fender with the same height as the superstructure would be effective to prevent the motion of the superstructure because of a significant reduction in the horizontal tsunami force.
