河口大桥地震响应及索力测试方法研究

发布时间：2018-03-26 15:27

本文选题：斜拉桥　切入点：反应谱分析　出处：《重庆大学》2015年硕士论文

【摘要】：河口大桥是兰州至永靖沿黄河快速通道的重点桥梁工程,同时是一座修建在高烈度区的大跨径的结合梁斜拉桥,,所以有必要对其动力特性及地震响应进行研究。不同的索力状态,对应着不同的主塔和主梁的内力状态,当结构承受地震作用时,就会产生不同的响应。索力测试方法的正确与合理可以保证结构的成桥受力状态达到设计预期的要求,从而保证结构的地震响应可以达到抗震设计的意图。本文在简述地震反应分析基本理论的基础上,以河口大桥为工程背景,对该桥进行反应谱分析、时程分析和索力测试的研究。主要研究内容有以下几点:①简要地介绍了国内外斜拉桥的发展现状、抗震分析研究现状,分析常见的斜拉桥的震害和原因,指出抗震分析的必要性,并扼要地概括了大跨度斜拉桥地震响应常用的分析方法。②利用大型有限元分析计算软件Midas/Civil,通过对斜拉桥结构进行适当的简化,建立其空间计算模型。在不考虑桩基与地基土对结构作用的情况下,计算并分析结构的动力特性。得出本桥的一阶频率0.15334Hz,结构周期为6.52s,表明结构的自振周期较长,有利于抗震。③对结构进行反应谱分析。计算出结构在不同荷载工况下的地震响应,其计算结果表明:在单向地震作用下,主塔的位移响应对纵向地震作用最为敏感而主梁的位移响应对横向地震作用最敏感,另外,对整体结构而言,以横向地震作用引起的内力响应为最大;在组合地震作用下,结构响应明显增大;应注意提高桥塔纵向和主梁横向的抗震能力。④对于大跨径斜拉桥而言,仅通过反应谱分析了解其地震响应是不够的。因此,根据规范的要求选取三类地震波对结构进行时程分析,探讨和比较了结构在不同荷载工况下结构的动力响应,当荷载工况相同时,三类地震波引起的地震响应规律大体一致;当荷载工况不同时,以横向地震作用为主的工况引起的地震响应较大。最后,在相同的工况下,比较反应谱分析和时程分析的计算结果,总体而言,在一致激励的情况下,反应谱分析的结果与时程分析的结果相比偏小。⑤总结索力测试常用理论,指出一般索力测试公式的缺点。分析索力测试的难点,包括如何考虑垂度、抗弯刚度等因素对索力测试的影响。并就每一个难点给出相应的解决方法,重点分析索力测试中的索力调整问题。最后,基于有限元原理,给出实用的索力测试方法,该方法能够考虑垂度的影响,适用于索力快速准确的测试。
[Abstract]:The Hekou Bridge is a key bridge project from Lanzhou to Yongjing along the Yellow River Expressway. At the same time, it is also a long-span cable-stayed bridge built in high intensity area, so it is necessary to study its dynamic characteristics and seismic response. Different cable force states correspond to different internal force states of main tower and main beam. When the structure is subjected to earthquake, it will produce different responses. The correctness and reasonableness of the cable force test method can ensure that the stress state of the bridge can meet the requirements of the design. So as to ensure that the seismic response of the structure can reach the purpose of seismic design. Based on the brief introduction of the basic theory of seismic response analysis and taking the Hekou Bridge as the engineering background, the paper analyzes the response spectrum of the bridge. Research on time history analysis and cable force test. The main research contents are as follows: 1: 1 briefly introduces the development of cable-stayed bridges at home and abroad, the present situation of seismic analysis, and analyzes the seismic damage and causes of common cable-stayed bridges. The necessity of seismic analysis is pointed out, and the commonly used method of seismic response analysis of long-span cable-stayed bridges is summarized briefly. Using the large-scale finite element analysis software Midas / Civil, the structure of cable-stayed bridges is properly simplified. The spatial calculation model is established. The dynamic characteristics of the structure are calculated and analyzed without considering the effect of pile foundation and soil on the structure. The first order frequency of the bridge is 0.15334Hzand the structural period is 6.52s, which indicates that the natural vibration period of the structure is longer. The seismic response of the structure under different load conditions is calculated. The results show that under unidirectional earthquake, the seismic response of the structure can be analyzed. The displacement response of the main tower is the most sensitive to the longitudinal earthquake, and the displacement response of the main beam is the most sensitive to the lateral earthquake. In addition, for the whole structure, the internal force response caused by the lateral earthquake is the largest. The seismic response of the long span cable-stayed bridge should be improved obviously, and the seismic response of the long span cable-stayed bridge should be improved only by the response spectrum analysis, so it is not enough to understand the seismic response of the long span cable-stayed bridge by means of response spectrum analysis. According to the requirements of the code, three kinds of seismic waves are selected to analyze the time history of the structure, and the dynamic response of the structure under different load conditions is discussed and compared. When the load condition is the same, the seismic response caused by the three kinds of seismic waves is generally the same. When the load condition is different, the seismic response caused by the lateral seismic action is larger. Finally, under the same working condition, the results of response spectrum analysis and time history analysis are compared. In general, under the condition of uniform excitation, The results of response spectrum analysis and time-history analysis are smaller than those of time-history analysis. The commonly used theory of cable force testing is summarized. The shortcomings of general cable force test formulas are pointed out. The difficulties of cable force test are analyzed, including how to consider sag, The influence of bending stiffness and other factors on cable force test is given. The corresponding solution is given for each difficulty, and the problem of cable force adjustment in cable force test is analyzed emphatically. Finally, based on the finite element principle, a practical cable force test method is given. This method can take the sag effect into account and is suitable for fast and accurate cable force measurement.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55

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