Abstract
On September 8, 2004, Typhoon No.0418 (Typhoon Songda) moved north along the western coast of Hokkaido, bringing high winds to wide areas in the storm zone. Omori Bridge, a 429-m-long I-girder bridge on National Highway 229, suffered the collapse of a 159-m-long section. The bridge spanned a reef that is surrounded by wave-dissipating blocks on the seaward side and precipices on the landward side. On the day of the collapse, waves were extremely high and winds were strong, and abnormal tide levels were attributed to the effect of the local topography. In this research, hydraulic model tests were performed to study the damage mechanism of the bridge and the wave forces that acted on it, in order to assess the safety of the truss bridge that will be erected for temporary restoration. The splash patterns were also examined to determine the conditions under which vehicles can safely run after the restoration.
