Abstract
A series of hydraulic experiments on tsunami-induced pressure and force acting on a bridge superstructure were conducted to investigate horizontal wave force taken into account in the β value and vertical wave force eliminated from the β value. From experimental results, it was revealed that the horizontal wave force can be evaluated using the drag force calculated from flow velocity at the seaward surface of the superstructure with a common value of the drag coefficient for rectangular plates and a projected area taking into account water surface elevation at the position of the superstructure. Furthermore, the pressure below the superstructure was found to decrease during the tsunami, and accordingly the resulting force was modeled as the lift force acting downward. From a comparison with the experimental results, it was found that the vertical wave force can be evaluated reasonably well using the sum of the downward lift force and the buoyancy force calculated from the water surface elevation.
