We can see a lot of gates against storm surge in the port area of Japan. This gate prevent storm surge from breaking into the land area. Though many gates has been constructed for these ten years, the reasonable design method for them have not been established. In this paper. we deal with the design standard of such a gate. The features of this paper is as followed.
1) We adopt steel and alminium alloy as materials of gates.
2) Impact forces and wave pressure are considered as external forces.
3) We can decide the allowable maximum deflection of agate.