主塔の高いエクストラドーズド橋の構造・経済特性

抄録

Exradosed bridges are recently increasing as a suitable bridge type between cable stayed bridges and box girder bridges, and the past tower height of exradosed bridges with three spans have been restricted under 10 to 15 meter. On the other hand, two span bridges supported by both ends have better precondition on stress fluctuation and displacement. It means that parts of tower and girder can be decreased with increasing a tower height. In this study, we analyzed characteristics of the three main parts (tower, girder, cable) and tried to optimize a structural system. As a result, we found that the most suitable tower height is about 25 meter, which is twice of exradosed bridges. This result was confirmed through a design and a construction, and this paper proposes a new optimal structural design.