AN ABSTRACT OF THE DISSERTATION OF

This dissertation examines tsunami and hurricane wave loads on bridge superstructures. Tsunamis have caused significant damage to coastal communities in recent years. For example, the 2011 Great East Japan Earthquake and resulting Tohoku Tsunami destroyed infrastructure along the east coast of Japan including bridge superstructures. Recent hurricanes have also caused extensive damage to coastal bridges in the southern US coastal areas along the Gulf of Mexico. Several coastal highway bridges were completely destroyed and many more experienced substantial damage during Hurricane Katrina in 2005. The first part of this study examines the tsunami loads on five California and three Oregon coastal bridges. Finite element (FE) models are used to simulate the tsunami loads on these bridges. The FE model includes water and air as a two-phase gravity flow separated by a water free-surface, and a bridge superstructure modeled as a rigid body. The quantities of interest include horizontal and vertical forces and overturning moment. Simulations and analyses are conducted for two tsunami load stages: (1). initial impact and overtopping, and (2). full inundation