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

本研究的主要目的是开发大跨度斜拉桥的新型结构体系。通过数值分析，研究了结构型式、斜拉组合梁斜拉桥的徐变和收缩与结构阻尼特性的关系，以及结构型式和钢梁尺寸对特大跨斜拉桥极限强度的影响。本文的研究内容总结如下：1。提高结构效率，提高结构阻尼：对不同类型斜拉桥进行阻尼分析，研究其阻尼特性。结果表明，通过适当提高钢索的阻尼，引入内部共振可以提高桥梁的结构阻尼。提高斜拉桥组合梁的结构效率：对中跨径斜拉桥进行了徐变和收缩分析，研究了斜拉桥的受力性能和适用跨径。本文还对新型组合楼板进行了试验和分析研究。提高特大跨径斜拉桥结构效率：对不同缆索组合方式和不同钢梁尺寸的斜拉桥进行弹塑性有限位移分析。基于解析估计的极限强度，讨论了梁的最小尺寸和最优结构组合。

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.