Tsunami-Like Wave Forces on an Elevated Coastal Structure: Effects of Flow Shielding and Channeling

Abstract

During a tsunami event, neighboring structures can significantly influence the forces experienced by an individual structure within an urban community. To assess the effects of adjacent structures on the resulting fluid flow, and the corresponding pressures and forces exerted on a structure, two tsunami-like waves were generated in the Large Wave Flume at the Hinsdale Wave Research Laboratory (HWRL) at Oregon State University. The forces and pressures on an elevated structure were measured for a reference geometry without neighboring structures, as well as for five structure configurations that included one or two neighboring structures arranged in layouts meant to be representative of prototypical rectangular buildings in subsections of a coastal community. Results showed that adjacent structures can shield a structure from the flow, causing decreased total forces with increasing blockage ratios. However, local channelization of the flow was found to increase local pressures, increasing the demands on structural components. Comparisons with ASCE 7-16 methods for determining force increase ratios due to channeling showed strong agreement for channeling-dominated configurations and bore-like waves that broke before impacting the elevated structure. In contrast, shielding-dominated configurations and waves that were unbroken on impacting the elevated structure showed that the ASCE 7-16 methods would overestimate force increase ratios.