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Seismic design of unseating prevention system for bridges

桥梁防脱系统抗震设计

基本信息

批准号：
15360247
负责人：
IZUNO Kazuyuki
金额：
$ 3.39万
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：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15360247/
关键词：
unseating prevention system shock absorber seismic design of bridge capacity design cable conservation of energy deformation limit collision between girders 落橋防止システム耐震設計運動方程式摩擦緩衝材道路橋

项目摘要

All road bridges in Japan have been fitted with a seismic unseating prevention system to prevent bridge girders from falling during an earthquake. In the current design of Japanese highway bridges, the necessary strength of the system is prescribed to be 1.5 times the reaction force for the dead load of the bridge girder. In other words, the capacity is stipulated in terms of the dead load alone, with no consideration of the dynamic response of the bridge system.With the emergence of the seismic unseating prevention system as an important issue in Japan, much research has been conducted in recent years. However, most studies have focused on specific factors in bridge collapse such as cable capacity, while research on the design procedure for the unseating prevention system itself remains limited. The bridge unseating prevention system has been designed based on theoretical considerations under many assumptions because it is difficult to evaluate the operation of the system during an actual earthquake. It is necessary to ensure that the system functions adequately during earthquakes.In this study, the design of connecting devices for preventing bridge girders from becoming unseated during strong seismic motion is extended to include consideration of the velocity response of the bridge. The demand strength and cross-sectional area of the connecting cable are derived based on conservation of energy considerations. The demand capacity of the connecting cable is also defined for the worst case that the girder falls from the pier. The installation of shock absorber with optimum stiffness based on its deformation limit and the cable stiffness is found to reduce both the stress on the cable and the required cross-sectional area.

日本所有公路桥都安装了防震脱座系统，以防止桥梁主梁在地震中倒塌。在目前的日本公路桥梁设计中，体系的必要强度被规定为桥梁主梁恒载反力的1.5倍。换言之，仅根据恒载来规定结构的承载能力，而没有考虑桥梁体系的动力响应。随着日本防震体系的出现，近年来开展了大量的研究工作。然而，大多数研究都集中在影响桥梁倒塌的具体因素上，如缆索的承载能力，而对脱座预防系统本身的设计程序的研究还很有限。桥梁脱座防御系统是在许多假设条件下基于理论考虑进行设计的，因为很难评估该系统在实际地震中的运行情况。为了确保系统在地震中充分发挥作用，本研究扩展了防止桥梁在强震作用下脱座的连接装置的设计，将桥梁的速度响应考虑在内。基于能量守恒的考虑，推导出连接缆索的需求强度和横截面积。并对梁从桥墩上掉落的最坏情况下的连接索需求能力进行了定义。根据拉索的变形极限和拉索的刚度，安装具有最佳刚度的减振器可以减小拉索上的应力和所需的横截面面积。