Abstract
Hydraulic experiments are conducted to investigate tsunami-induced wave force acting on the superstructure of a bridge and its effect on the motion of the superstructure. In the hydraulic experiments, a long-period wave without wave breaking are generated against a movable model of the superstructure to determine whether it moves or not and a fixed model of the superstructure to measure tsunami force and wave pressure acting on it. From experimental results, it is found that the horizontal component of the tsunami force can be evaluated using the drag force calculated from the flow velocity at the seaward surface of the superstructure model, and the vertical component of the tsunami force is overestimated by the buoyancy force calculated from the water surface elevation at the position of the superstructure model. Furthermore, it is revealed that whether the superstructure model moves or not and the time of the initiation of its motion can be evaluated by a comparison between the horizontal tsunami force and the static friction force considering the vertical tsunami force, suggesting that the consideration of the vertical tsunami force in the static friction force is essential when assessing the motion of a bridge superstructure.
