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Evaluation of necessary capacity and development of dynamic design method for unseting prevention cables of bridges with shock absorbing devices

减震桥梁防滑索必要能力评价及动态设计方法开发

基本信息

批准号：
17360219
负责人：
IZUNO Kazuyuki
金额：
$ 5.88万
依托单位：
Ritsumeikan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

A rational design method of an unseating prevention cable is not established yet especially for that with a shock absorber. This research aims to clarify a dynamic property of an unseating prevention cable with a shock absorber considering its deformation limit and nonlinearity. The results show that the shock absorber can be designed according to the law of conservation of energy.Then, the design method for the unseating prevention cable was studied for the continuous girder bridges. Once a continuous girder bridge becomes unseated at one pier, the girder is likely to collapse due to bending or shear forces. In this study, the necessary capacity of an unseating prevention cable to prevent the girder of a continuous girder bridge from collapsing was investigated using static and dynamic analysis. The static analysis verified that an unseating prevention cable designed using the present design procedure had sufficient capacity to resist the excessive bending moment and shear force caused by falling of the girder. The dynamic analysis showed that a part of the girder yields due to the large bending moment if a low stiffness cable is used as the unseating prevention cable.Further, the relative velocity during collision between the adjacent bridges was estimated in order to estimate the collision force. The elasto-plastic response analyses were carried out using 2-degree-of freedom model. The parametric study was conducted on the influence of the relative velocity of type of input motion, ground classifications, damping ratio and collision spring. As compared to elastic responses, the relative velocity was reduced in about half and it ranged from 0.3 to 2.5m/sec. Finally, it is clarified that the ground classifications, differential ratio of natural period and collision spring strongly affect on the relative velocity during pounding girders.

目前还没有一种合理的防脱座电缆设计方法，特别是带减震器的防脱座电缆设计方法。研究了考虑变形极限和非线性的带减振器的防失座索的动力特性。结果表明，减振器可以根据能量守恒定律进行设计。在此基础上，研究了连续梁桥防脱落索的设计方法。连续梁桥一旦在某一桥墩处脱臼，梁就有可能因弯曲或剪力而倒塌。本文采用静力分析和动力分析的方法，研究了防止连续梁桥主梁坍塌所需的防脱索承载力。静力分析结果表明，采用本设计方法设计的防脱座索具有足够的抗梁跌落引起的过大弯矩和剪切力的能力。动力分析表明，采用低刚度索作为防脱位索时，由于弯矩过大，部分梁产生屈服。进一步，估计相邻桥梁碰撞时的相对速度，以估计碰撞力。采用二自由度模型进行弹塑性响应分析。对输入运动类型的相对速度、地面分类、阻尼比和碰撞弹簧的影响进行了参数化研究。与弹性响应相比，相对速度降低了约一半，在0.3 ~ 2.5m/sec之间。最后阐明了地基类型、自然周期差比和碰撞弹簧对冲击梁的相对速度有较大影响。