As a first step of this new approach, we will focus on residential (light-frame wood) buildings which make up 90% of the building stock in the US and are where people spend approximately half of the hours in their day, Because of the sheer number of residential buildings in these coastal communities, understanding tsunami impact on these structures and the expected damage level is necessary to reduce damage and loss of life.

The goals of this NEESR-II project are to (1) develop a methodology to assess the risk of residential structures to tsunami inundation and wave forces through a systematic experimental study coupled with a numerical probability of failure analysis; (2) enable the development of innovative retrofit products by developing a structural testing protocol that is representative of hydraulic impact/forces during a tsunami; and (3) refine the current hydraulic force equation in ASCE 7 based on a series of wave basin tests to account for building density and other variables. This transformative project builds on the knowledge base of tsunami inundation at regional scales and the tsunami-structure understanding at the building scale from other NEESR projects. This project also integrates new large-scale physical modeling and numerical modeling efforts to mitigate both structural risk to building damage and loss of life in a community-wide tsunami inundation event. NSF award abstract

Phase III, the third and final phase of this project, will begin in May 2009. Based on the results of data analyzed from phase II, researchers will construct a bathymetry with a significant cross-shore feature, such as a channel, which will generate strong 3D changes in the flow patterns during runup and rundown. This feature will be designed to mimic a realistic shallow water bathymetry irregularities, and will provide insight into the magnitude of flow variations due to such local features. Free surface maps will be created, and turbulence information will be extracted from numerous velocity measurements. In addition, overhead video and dye studies will be used to visualize flow patterns. NSF award abstract

Phase I took place in the spring of 2007. The purpose of this set of experiments was to obtain a detailed and dense set of free surface and velocity measurements for 3D tsunami (long wave) breaking. Breaking will be induced through wave focusing. There was no bathymetry in the Tsunami Wave Basin during this phase; it was a flat bottom. Phase II will begin in July 2008 utilizing a 1:15 to 1:30 beach constructed in the Tsunami Wave Basin. The roughness type will include both fixed and movable sand and gravel, stripes and wires (simulating bushes and trees), and small blocks (simulating small structures in the path of tsunami inundation). 2HD runup time series will be digitized from overhead cameras, and the inundation limit will be manually traced after each experimental trial. These experimental settings will simulate situations closer to what tsunamis encounter on natural beaches. With this data, accurate bottom dissipation models will be developed for transient tsunami flow, improving significantly upon the traditional approach. NSF award abstract

Phase I took place in the spring of 2007. The purpose of this set of experiments was to obtain a detailed and dense set of free surface and velocity measurements for 3D tsunami (long wave) breaking. Breaking will be induced through wave focusing. There was no bathymetry in the Tsunami Wave Basin during this phase; it was a flat bottom. NSF award abstract