強潮流下の海峡部に係留した台船からの80m鋼桁吊上げ工事

抄録

After collapse of the KB Bridge in Palau in fall, 1996, a modern hybrid extra-dosed bridge with three spans was constructed with financial aid by the Government of Japan. The main span and side span are 247m long and 82m long, respectively. As one of the efforts to minimize the moment at the main towers caused by shorter side spans, a hybrid structure of concrete and steel girder is employed.
The steel girder was manufactured and assembled in Vietnam and China. The completed steel girder was transported by an 8000 ton barge and a 2700 horse power tugboat to Palau. The barge was towed by three local tugboats and moored at the construction site, where tidal current speed reaches at 4 knots. Since the hydraulic forces on the barge were expected to be large, measurement and prediction of sea surface elevation and tidal current were carefully made. Based on those results, the mooring system was designed, and the design and operational conditions were established.