Dynamic Response of Structures to Tsunami Attack

Abstract

Present practice to analyze tsunami forces on coastal structures is generally based on static loading analysis. This compares maximum predicted forces with the resistance to overturning or sliding, but does not account for the fact that some structural motion could occur without failure. While applied forces at some threshold level will give incipient motion, actual motion will be determined by the force exceeding the threshold level and the related acceleration. Three different levels of forces must then be considered: a force that will not exceed the threshold causing incipient motion; a magnitude and duration which will cause motion but not failure; and a magnitude and duration which will cause structural failure. It is also necessary to investigate the axis of rotation for structural failure. Once motion is initiated there would be foundation failure under the toe, moving the axis of rotation inward under the structure. This increases the acceleration and causes increased motion.