高墩大跨度连续刚构桥地震响应分析

发布时间：2018-10-24 13:54

【摘要】：随着我国经济和建设事业的快速发展,大跨度连续刚构桥梁也受到大量应用。由于刚构桥良好的跨越能力,因此受到越来越多的山区道路的青睐,且桥墩的修建也越来越高,因此在本文中对高墩大跨连续刚构桥的地震反应做了一些探讨。本文的主要研究内容有以下几点:(1)利用MIDAS/CIVIL专业有限元分析软件对薛家坝2号高墩大跨度连续刚构桥进行结构的动力特性分析,分析结构的振动规律。结果发现:①结构的第一阶振型为体系竖弯+纵飘,有可能在顺桥向的桥墩墩顶、墩底产生较大塑性转角,应对桥墩的墩顶及墩底给予重视,加强在这些塑性铰区的设计、配筋;②第二阶和第三阶振型都表现为横弯,桥的横向刚度较低,可能会产生较大的横向位移;③高阶振型主要影响的是桥梁的竖向地震响应。(2)对高墩大跨度刚构桥进行反应谱地震响应分析研究,通过比较在三种工况下各方向地震激励对结构各种内力、位移的贡献,得出地震波的组合方式。经过分析发现:①纵桥向,横桥向的地震激励必须进行考虑,而当设防烈度较低时竖桥向地震的地震激励可不进行考虑;②桥墩的横隔板对桥墩的位移影响特别大,尤其是顺桥向和横桥向位移。因此在空心墩的设计时,要合理给予设计,在合理的位置设置横隔板,会有效的降低桥墩的位移。(3)采用三组地震波对结构进行地震响应分析,选取出最不利地震波。对比发现,尽管地震波的加速度峰值相同,但是地震波的频谱特性对结构地震响应具有明显的影响。(4)将反应谱分析与时程分析的结果进行对比,选取满足抗震规范的地震波。(5)采用动态时程分析方法对在边墩墩顶上设置高阻尼橡胶支座减隔震装置进行分析,分析在设置减隔震支座下结构的地震响应。发现在地震力的作用下:①支座对主梁的纵桥向弯矩几乎没有影响,但对主梁的横桥向剪力却有着十分明显的降低;②支座对于刚构桥梁主墩横桥向剪力的降低很小。但是刚构桥梁支座的应用会十分有效的降低边墩横桥向剪力,这是因为支座设置在边墩的墩顶,也证明支座对于横桥向地震力的减震效果非常明显;③支座的应用会使主墩墩底纵桥向弯矩、纵桥向剪力变小,边墩弯矩和纵桥向剪力变大,这有利于结构的整体受力,提高结构的抗震性能;④支座对主梁和主墩的位移影响几乎可以考虑不计;⑤地震力作用下,主梁的内力最大值主梁根部位置,桥墩的地震反应内力在墩顶和墩底最大,因此需要特别注意这些关键位置的抗震设计。
[Abstract]:With the rapid development of economy and construction in China, long-span continuous rigid frame bridges are also widely used. Due to the good span capacity of rigid frame bridge, it is favored by more and more mountain roads, and the construction of bridge piers is becoming higher and higher. Therefore, the seismic response of long-span continuous rigid frame bridge with high piers is discussed in this paper. The main contents of this paper are as follows: (1) the dynamic characteristics of the structure of Xuejiaba No. 2 long-span continuous rigid frame bridge with high pier and large span are analyzed by using MIDAS/CIVIL software, and the vibration law of the structure is analyzed. The results show that: 1 the first vibration mode of the structure is vertical bending and longitudinal floating, and it is possible to produce a large plastic turning angle at the top of the pier and the bottom of the pier in the direction of the bridge, so we should pay attention to the pier top and the bottom of the pier, and strengthen the design of these plastic hinges. (2) the second and third vibration modes are both transverse bending, and the lateral stiffness of the bridge is low, which may result in larger lateral displacement. (2) the response spectrum seismic response of long-span rigid frame bridge with high piers is analyzed and studied, and the contribution of seismic excitation in different directions to the internal force and displacement of the structure is compared under three working conditions. The combination mode of seismic wave is obtained. It is found that: (1) the seismic excitation in the longitudinal and transverse direction must be considered, but the seismic excitation of the vertical bridge should not be considered when the fortification intensity is low, and the displacement of the pier is especially affected by the transverse partition of the pier. Especially the displacement along the bridge and across the bridge. Therefore, in the design of hollow piers, it is necessary to design reasonably and set the transverse diaphragm in a reasonable position, which will effectively reduce the displacement of the bridge piers. (3) three sets of seismic waves are used to analyze the seismic response of the structure, and the most unfavorable seismic waves are selected. It is found that, although the peak acceleration of seismic wave is the same, the spectral characteristics of seismic wave have obvious influence on the seismic response of the structure. (4) the results of response spectrum analysis and time-history analysis are compared. (5) dynamic time-history analysis method is used to analyze the seismic isolation device with high damping rubber bearing on the top of side pier, and to analyze the seismic response of the structure under the installation of seismic isolation support. It is found that: (1) the bearing has little effect on the longitudinal moment of the main beam, but it has a very obvious decrease in the transverse shear force of the main beam, and the support has little effect on the shear force of the main pier of the rigid frame bridge. But the application of rigid frame bridge support can reduce the lateral shear force of lateral bridge effectively, because the support is located at the top of the pier of side pier, and it also proves that the effect of bearing on the seismic force of lateral bridge is very obvious. (3) the application of the support will make the bending moment of the longitudinal bridge at the bottom of the main pier, the shearing force of the longitudinal bridge becoming smaller, the moment of the side pier and the longitudinal shear force of the longitudinal bridge becoming larger, which is beneficial to the overall stress of the structure and the improvement of the seismic performance of the structure; (5) under the action of seismic force, the maximum internal force of the main beam is located at the root of the main beam, and the internal force of the pier is the largest at the top of the pier and the bottom of the pier. Therefore, special attention should be paid to the seismic design of these key locations.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55;U448.23

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