【作者】 曾伟东；

【导师】 李传习； 高荣堂；

【作者基本信息】 长沙理工大学 ， 建筑与土木工程， 2008， 硕士

【摘要】 荷载试验是一种重要的检测手段,可以为决策者对桥梁的承载能力做出科学地评估,提供有力、直观的依据,可以为新的结构、新的设计理论和新的施工工艺的发展与应用积累实践资料。九江大桥斜拉主桥为独塔斜拉桥,索塔采用塔梁墩固结体系,从桥面算起塔高81米,为H型带水平隔板的塔柱。本文以现代桥梁设计理论、有限元法、随机振动、振动测试与分析技术为理论基础,在总结有关桥梁的荷载试验方法的基础上,对九江斜拉主桥的荷载试验方法进行了研究和设计,具体开展了以下几方面的工作:通过对九江斜拉主桥的理论分析,在保证荷载试验效果的前提下,确定试验的控制荷载和加载工况,将各种工况下结构控制截面的实际变形或者应力同理论计算值进行了比较,计算出结构的校验系数。根据计算得到的结构的校验系数,确定了该桥的实际承载能力。桥梁结构的振动问题影响因素复杂,仅靠理论分析还不能满足工程应用的要求。为了测定该桥在动荷载作用下的真实情况,分别进行了跑车试验、刹车试验和跳车试验。根据控制断面在上述工况下的时程曲线图,分析确定了该桥的实际的冲击系数,并同理论设计时根据规范所取的冲击系数进行了比较。根据实测结果为公路管理、养护部门提出了有益的建议。利用ANSYS软件建立了斜拉桥的空间有限元模型,并进行了理论上的模态分析,得到了该桥理论上的自振频率与振型。通过对实桥的脉动测试,分析确定了九江斜拉主桥实测的模态参数(包括振型、频率以及阻尼比)。实测结果与理论计算结果的对比表明:该桥具有良好的动力性能。根据九江大桥的结构特点,分析了产生这些振型的原因。对斜拉桥的拉索在换索前及换索后的模态进行了测试,比较换索前后的模态试验结果,对桥梁的运营状况作进一步分析与判断。更多还原

【Abstract】 Load test is an important testing method, which can provide advantageousa nd direct bases for administrators to evaluate carrying capacity of bridge. Especially for the new structure, bridge design theory and working technics it can provide valid actual datum. Jiujiang Bridge is a consolidation system of tower-girder-fursta with 81 meters high. Based on the method of modern bridge design, infinite element, random vibration, and vibration testing and analysis technology this paper studies and designs the load test plan of Jiujiang Cable-stayed Bridge by summarizing the load test plans of some concerned bridges.Through the the oretical analys is of Jiujiang bridge, this paper makes sure the controlling load and loading case under the condition of ensuring the load test efficiency. According to the results of comparison between the actual value and the theoretical value of the controlling section this paper makes clear the actual carrying capacity of bridge.The problem of bridge vibration is very complicated and the analysis in theory still can not meet the requirement of the engineering application. In order to test the actual condition when the bridge is forced by dynamical load, running test, braking test and jumping test are carried out respectively. According to the time-travel curve under the cases above-mentioned, the actual figure of impact coefficient comes out. At the same time this paper compares it with that in theory and brings forward beneficial advices for the road managing and maintaining department.Theoretical mode analysis is made by establishing the dimensional infinite element model of Jiujiang Bridge with ANSYS software, thus natural vibration frequency and mode shape of Jiujiang Bridge theoretically are concluded. With pulsation measurement method this paper tests the actual mode parameters (including mode shape, natural vibration frequency andd ampingr atio). The comparison between actual results and those in theory indicatesth at this bridge is qualified with satisfactory dynamical peculiarity. Furthermore, this paper analyses the causes that these mode shape lie in according to the structure characteristic of Jiujiang Bridge.Mode analysis is also made before and after ranging cables and the condition of Jiujiang Bridge are summarized further by comparing the testing results.更多还原