【作者】 乔晋姿；

【导师】 祝兵；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 随着斜拉桥跨径的增大和柔索的采用,其索力对梁体的内力影响越来越显著,已成为控制全桥受力的关键。如何合理地确定索力,使斜拉桥处于合理地受力状态,已成为斜拉桥设计中的关键问题。并且大跨度斜拉桥一般都是交通运输的枢纽工程,一旦在地震中遭到破坏,将会造成巨大的直接和间接经济损失。因此,对斜拉桥进行正确有效的抗震设计,确保其抗震安全性同样具有非常重要的意义。论文首先简要介绍了混凝土斜拉桥的发展概况及其结构体系和结构特点;然后以实际工程为背景,运用大型有限元软件MIDAS/CIVIL 2006,建立了完整的全桥组合有限元模型;以未知荷载系数法为基础,按所取控制目标优化索力,确定合理成桥状态;然后采用倒拆—正装迭代法确定合理施工索力。最后,采用反应谱分析方法对桥梁的地震响应进行了计算分析。其中对标准反应谱进行长周期和阻尼比修正,采用修正后的谱曲线作为输入的谱曲线;分别考虑了不同阻尼比值下该桥的纵向、横向、竖向地震响应,并对不同阻尼比情况下三向地震反应进行了分析对比。本文的工作取得一些初步的研究成果,可为大跨斜拉桥设计提供参考。更多还原

【Abstract】 With the increasing of the span and the using of the flexibility cable, the cable forces have more and more important influence on the distribution of internal force of the whole structure system and they have become the key to control the forcing of the whole bridge. So, how to reasonably determine the cable forces to make the internal force state of the cable-stayed bridge rational has become the key point in the design of cable-stayed bridges. And also, long span cable-stayed bridges generally are the key structures of transportation system. Great direct and indirect economic loss will be caused if these bridges get damaged in an earthquake. Therefore the correct and effective earthquake resistance design and assurance of earthquake safety of cable-stayed bridges have the same importance.Firstly, the development situation, structural systems and structural characteristics of concrete cable-stayed bridge are presented in this thesis. Then the integrated finite element model based on a practical project is built up by using finite element software called MIDAS/CIVIL 2006.Secondly, the unknown load-factor method is used which takes the minimum stress of girder and tower in the finished state as the objective function to decide reasonable finished state, then the backward analysis-forward iteration method is adopted to determine the reasonable construction cable forces.Finally, the seismic response is calculated and analysed by means of the response spectrum analysis. In this part, the standard seismic response spectrum’s long period and damping ratio are modified, and the modified spectrum curves with different values of damping ratio are input in longitudinal, transverse and vertical direction respectively, the result of the seismic response with different values of damping ratio of the bridge in three directions is studied and compared.Some conclusions are obtained in this thesis, and can be referenced in the design of long span cable-stayed bridges.更多还原