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

本研究的主要目的是发展大跨度斜拉桥的新型结构体系。通过数值分析，研究了斜拉组合梁斜拉桥的结构减振特性与结构组合、徐变和收缩的关系，以及结构组合和钢梁尺寸对超大跨度斜拉桥极限强度的影响。本研究的内容概括如下：1.研究内容。提高结构的减振效率：对不同类型的斜拉桥进行减振分析，研究其减振特性。结果表明：1.适当提高拉索的内共振，可以提高桥梁结构的减振效果。提高斜拉桥组合梁的结构效率：通过对大跨度斜拉组合梁桥的徐变和收缩分析，研究其受力性能和适用跨度。对组合梁桥新型组合楼板进行了试验和分析研究。超大跨度斜拉桥结构效率的提高：对不同拉索组合和不同钢梁尺寸的斜拉桥进行了弹塑性有限位移分析。在极限强度解析估计的基础上，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.