Abstract
Utatsu Bridge, a prestressed concrete bridge, suffered enormous damage from the destructive tsunami waves triggered by Great East Japan Earthquake, on March 11th, 2011. Based on the field survey, it is clear that the bridge girders S3~S10 flowed out. With the application of the video recording tsunami-hit, the wave height and velocity histories are plotted. Meanwhile, the outflow mechanism of girder (S9) is analyzed, based on video result. On the other hand, two dimensional (2-D) simulation is conducted for Utatsu Town. The tsunami process, wave height and velocity histories are obtained. Besides, the outflow mechanism of girder (S9) is analyzed by simulation result once more. From video and simulation, it is known that the wave height rises slowly, which indicates no bore wave occurs; furthermore, it is found that when girder of Utatsu Bridge is flooded, the friction resistance is insufficient to resist tsunami force.
