Acoustic Load On A Plate With Application To Water-borne Tsunami Debris

Abstract

Water-borne debris carried by the strong flow of water of a tsunami, flood, or storm surge can damage structures in the inundation zone. A prominent example of such debris is a shipping container. Research on such debris has focused on the impact between the debris and the structure. This work instead focuses on the effect of the water on the debris once the debris has made contact with a structure. A 2- dimensional analytical model of the draft (submerged) portion of the water-impacted panel of a shipping container is presented. The water carrying the shipping container is modeled as an acoustic load, which provides a conservative upper bound of the pressure of the water on the container. The draft portion of the water-impacted face of the shipping container is modeled as a Kirchhoff-Love plate, which describes the elastic deformation of this portion of the container. The model is validated using finite element models for the six cases of a 20-foot and 40-foot shipping container, each at 100%, 50%, or zero cargo capacity. The results indicate that varying the mass of the cargo in the shipping container yields no significant difference in the deformation. The acoustic load is by far the most significant at the bottom of the container, whereas the rest of the water-impacted panel experiences steady displacement, continuing with the constant velocity of the water. Most of the deformation of the important bottom region occurs within the acoustic time scale of the water.