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This paper presents the first of a series of case studies on the seismic design of long span bridges （cable-stayed bridges, suspension bridges and arch bridges） under a cooperative research project on seismic behavior and design of highway bridges between the State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University and the Multidisciplinary Center for Earthquake Engineering Research, University at Buffalo. The objective of this series of case studies is to examine the differences and similarities on the seismic design practice of long span bridges in China and the U.S., to identify research needs and to develop design guidelines beneficial to bridge engineers in both countries. Unlike short to medium span bridges, long span bridges are not included in most seismic design specifications, mainly because they are location dependent and structurally unique. In this paper, an available model of a steel tied half through arch bridge with a main span of 550m in China is discussed. Analysis is focused on comparisons of the seismic responses due to different ground motions. Seismic design criteria and seismic performance requirements for long span bridges in both countries were first introduced and compared, and then three near field earthquake records with large vertical components were selected as the excitations to examine the seismic behavior and seismic vulnerability of the bridge. Results show that （1） the selected near field ground motions cause larger responses to key components （critical sections） of the bridge （such as arch rib ends） with a maximum increase of more than twice those caused by the site specific ground motions; （2） piers, longitudinal girders and arch crowns are more vulnerable to vertical motions, especially their axial forces; and （3） large vertical components of near field ground motions may not significantly affect the bridge＇s internal forces provided that their peak acceleration spectra ordinates only appear at periods of less than 0.2s. However, they may have more influence on the longitudinal displacements of sliding bearings due to their large displacement spectra ordinates at the fundamental period of the bridge. 相似文献
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城市防震减灾能力本身是一个涉及因素众多的复杂体系，对它的评估也是涉及到地震科学、社会科学和经济科学的交叉学科问题. 本文首先提出了城市防震减灾能力的概念，把人员伤亡、经济损失和震后恢复时间等3个方面作为衡量城市防震减灾能力的准则；围绕这3个准则，从影响城市防震减灾能力的众多复杂因素中抽取出六大因素，并用一些简单、可测量的指标来代表这六大因素，建立起城市防震减灾能力指标体系；然后建立起指标体系与上述3个方面评价准则¾人员伤亡、经济损失和恢复时间的联系；最后，用灰色关联分析方法将3个评价准则综合成一个防震减灾能力指数.从而为城市防震减灾能力评估提供了一个较系统、完整的理论体系框架. 理论体系的建立能够在绝对上、定量上评价城市的防震减灾能力，从而指导城市进行防震减灾决策. 相似文献
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对索的准确模拟有时应考虑弯曲刚度的影响.在已有研究基础上,考虑弯曲刚度对悬索静力构形的影响,分别推导了两端固结和两端铰接边界条件下水平悬索面内自由振动的解析解,并修正了已有文献中的不足之处,该解在理论上较已有解析解更为准确,它可看作是已有文献在均匀索情况下的解析解.本文推导的解析解具有一定的理论意义. 相似文献
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复杂结构地震动输入方向的基本原理及其影响 总被引：2，自引：0，他引：2
对于复杂结构，在动力分析中地震波的最不利输入方向对应着结构的最不利反应。本文从叠加原理出发，详细论述了用反应谱法求解结构的最不利输入方向问题，并通过工程实例来说明其影响程度。 相似文献
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Introduction At the end of last century, the Committee of International Decade for Natural Disaster Re-duction had called on evaluating the ability reducing earthquake disasters of cities. However, since efficient method to assess earthquake loss of cities does not exist, the proposition did not come true. In 1994, China government put forward that the cities with dense population or developed economy and the areas off the seashore should have the ability to resist earthquake (M=6). Un-dou… 相似文献
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抗震销在上海莘庄立交工程的设计中,由于构造的特殊性,其力学特性难以用常规方法表达。基于位移和多级设防的抗震思想,以莘庄立交工程中的一异型板桥为例,首次以两个包含极端边界条件的结构分析模型考虑抗震销这一特殊构造措施对结构的影响,并按照实际结构构造充分考虑材料非线性及连接构件的非线性等因素,分别以弹塑性纤维梁柱单元、空间滑动支座单元和接触单元模拟桥墩屈服、支座滑动、相邻结构之间碰撞,建立了空间非线性时程反应分析模型,并进行了设计和罕遇地震水平两个概率水准下的地震反应分析和抗震性能评估,并根据分析结果的对比,提出强化抗震销刚度的建议。 相似文献
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城市建构筑物地震损失预测研究 总被引：12，自引：0，他引：12
本文提出了预测城市建构筑物在不同烈度下地震灾害损失的简易方法。首先分析了影响城市建构筑物抗震能力的3个因素——抗震设防情况、建筑年代和结构类型;然后提出了建构筑物抗震能力指数的概念,并确定了将上述3因素综合成建构筑物抗震能力指数的方法;最后利用“九五”期间所做的大中城市的震害预测结果统计回归出房屋抗震能力指数与地震灾害损失——人员伤亡、经济损失和震后恢复时间的关系。由此可以得到建构筑物在不同烈度下地震灾害损失的简易计算方法。 相似文献