Study on Improvement of Structural Efficiency in Long-Span Cable-Stayed Bridges

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The main objective of this study is to develop new structural system for long span cable-stayed bridges. The relation between the structural damping characteristics and the structural assembly, the creep and shrinkage of cable-stayed composite girder cable-stayed bridges, and the effects of structural assembly and the dimension of steel girder on the ultimate strength of very long span cable-stayed bridges, are investigated by conducting numerical analyses. The contents of the present study are summarized as follows.1. Improvement of structural efficiency for higher structural damping : The damping analyses of various types of cable-stayed bridges were conducted to investigate their damping characteristics. It is concluded that the structural damping of bridges can be made higher by introducing the internal resonance of cables whose damping is improved appropriately.2. Improvement of structural efficiency in composite girder of cable-stayed bridges : The creep and shrinkage analyses of cable-stayed composite girder bridges with medium span were conducted to investigate their mechanical behaviors and applicable span length. The new type of composite floor slab for composite girder bridges was also studied experimentally as well as analytically.3. Improvement of structural efficiency for very long span cable-stayed bridges : The elasto-plastic finite displacement analyses were conducted for cable-stayed bridges with different assembly of cables and different dimensions of steel girders. The minimum size of girder and the optimal structural assembly were discussed based on the analytically estimated ultimate strength.