The storm surge associated with Hurricane Katrina caused tremendous damage along the Gulf Coast in Louisiana, Mississippi, and Alabama. Similar damage was observed subsequent to the Indian Ocean tsunami of December 26, 2004. In order to gain a better understanding of the performance of engineered structures subjected to coastal inundation due to tsunami or hurricane storm surge, the writers surveyed damage to bridges, buildings, and other coastal infrastructure subsequent to Hurricane Katrina. Numerous lessons were learned from analysis of the observed damage, and these are reported herein. A number of structures experienced significant structural damage due to storm surge and wave action. Structural members submerged during the inundation were subjected to significant hydrostatic uplift forces due to buoyancy, enhanced by trapped air pockets, and to hydrodynamic uplift forces due to wave action. Any floating or mobile object in the nearshore/onshore areas can become floating debris, affecting structures in two ways: impact and water damming. Foundation soils and foundation systems are at risk from shear-and liquefaction-induced scour, unless designed appropriately.

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A series of experiments have been carried out in the large wave flume (LWF) at Oregon State University to quantify tsunami bore forces on structures. These tests included "offshore" solitary waves, with heights up to 1.3 m, that traveled over aflat bottom, up a sloping beach, and breaking onto a flat reef. Standing water depths on the reef varied from 0.05 m to 0.3 m. Resulting bores on the reef measured up to approximately 0.8 m. After propagating along the reef, the bores struck a vertical wall. The resulting forces and pressures on the wall were measured. The test setup in the LWF is described, and the. experimental results are reported. The results include forces and pressure distributions. Results show that the bores propagated with a Froude number of approximately 2 and that the forces follow Froude scaling. Finally, a design formula for the maximum impact force is given. The formula is shown to be an improvement over existing formulas found in the littérature.

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A series of experiments have been carried out at Oregon State University to quantify tsunami bore forces on structures. Phase 1 of the tests was carried out in the Tsunami Wave Basin (TWB), while Phase II of the tests were carried out in the Large Wave Flume (LWF) at approximately twice the scale of the Phase I tests. These latter tests included ‘offshore’ solitary waves, with heights up to 1.3 m, that traveled over a flat bottom, up a sloping beach and breaking onto a flat ‘fringing reef’. Standing water depths on the reef varied from 0.05 m to 0.3 m. Resulting bores on the reef measured up to approximately 0.8 m. After propagating along the reef, the bores struck a vertical wall. The resulting forces and pressures on the wall were measured. The test setup for the Phase II tests in the LWF is described and the experimental results are reported. The results include forces and pressure distributions. Results show that the bores propagated with a Froude number of approximately 2, and that the forces follow Froude scaling. Finally, a design formula for the maximum impact force is given. The formula is shown to be an improvement over existing formulas found in the literature. The lateral forces are shown to be quite significant compared to traditional lateral loads on vertical wall elements.

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