In the design of a horizontal plate, uplift forces generated not only by normal waves but also by tsunami must be considered. In this study, we conducted a hydraulic model test and a numerical simulation (CADMAS-SURF) in order to investigate the characteristics of uplift forces by tsunami exerted underneath a deck of horizontal plate. The maximum uplift pressure by tsunami is almost equal to the hydrostatic pressure induced by the rise of water surface, and the uplift force can be reduced by preparing openings to discharge the trapped air under the plate. The calculated results of water surface and uplift pressure by CADMAS-SURF were fairly well in agreement with the experimental results.
