Experimental investigation of tsunami bore-induced forces and pressures on skewed box section bridges

Abstract

Tsunamis in Indonesia (2004) and Japan (2011) severely affected communities bordering the Indian Ocean and Japan's east coast. Despite the plausible findings arising from the available studies, the research on the impact of tsunami bore forces applied to bridges of different designs is limited. This is because the estimation methods for tsunami-induced loads presented in the literature have mainly been developed for buildings and require careful adaptation to apply to bridges. The main focus of the present study is to experimentally examine the interaction between a tsunami bore and a box section bridge with different orientations to the direction of the incoming bore, bore strengths, and deck clearances. The experiments were conducted in a 15-m-long, 1.2-m-wide, and 1.2-m-deep wave flume. The forces and pressures applied to the bridge, the bore heights, and the velocities were measured. It was found that the skewed bridge deck is subjected to additional force and moment components, namely the cross-stream force (Fy) and the rolling and yawing moments (Mx and Mz). These components are non-existent for the unskewed bridge deck. Based on the experimental results, equations were proposed for estimating tsunami forces for a box section bridge deck.