斜拉索—辅助索索网体系动力特性和减振研究

发布时间：2018-06-20 21:13

本文选题：振动控制 + 辅助索　；参考：《重庆交通大学》2015年硕士论文

【摘要】：随着经济发展和科学的进步,桥梁朝着大跨度方向发展,斜拉桥在现代交通体系中起着日益重要的作用,而斜拉索则是斜拉桥中最主要的受力构件。由于斜拉索具有质量轻、阻尼低、柔度大等特点,极易在外界的激励下产生各种类型的有害振动。斜拉索的振动会引起拉索锚固端的疲劳损伤甚至破坏,从而影响桥梁的正常使用,因此如何有效的对斜拉索的振动进行控制是桥梁动力学目前最重要的课题之一。斜拉索常用的制振措施有：传统的气动措施、设置集中阻尼器、设置辅助索。辅助索将斜拉索分成若干段,从而提高了斜拉索刚度。同时将空间结构上独立的斜拉索连接形成索网体系,提高了索面的整体刚度。设置辅助索不能提高索网体系的耗能能力,制振效果仍受一定限制。在辅助索端或辅助索与斜拉索连接处安装集中阻尼能提高索网体系的阻尼,从而使其减振效果显著提高。斜拉索-辅助索索网体系的减振机理仍缺乏可靠的理论依据,特别是在参数的选取及优化方面还不完善。本文通过理论分析和有限元仿真相结合的方法分析了辅助索参数的选取,及辅助索不同参数对斜拉索-辅助索索网体系制振效果的影响规律,研究了集中阻尼器类型的选择和位置的选取及优化。本文以水土嘉陵江大桥跨中斜拉索为研究背景,首先对单根斜拉索进行静力及动力特性分析。确立了单根拉索的理论模型,并建立了合理的有限元仿真模型。利用有限元软件ANSYS对单根拉索的动力特性进行仿真分析。考虑斜拉索垂度效应和阻尼效应等因素对拉索各阶模态的频率、阻尼比、振形的影响效果。其次对辅助索的减振机理进行理论研究,通过有限元仿真模型分析辅助索的张拉方式、安装点位、截面面积、初始张拉力等参数对索网结构动力特性的影响规律。接着建立索网体系的自由振动方程,并结合边界方程、变形协调方程和力的平衡方程得到系统的振动模态。利用近似解析式研究索网的整体刚度和阻尼器的刚度对系统模态频率和阻尼比的影响。提出两种可用于索网减振的集中阻尼器,并确定阻尼器的布置方案。通过ANSYS软件建立仿真模型,用复模态分析方法得出设置两种阻尼器时索网结构的模态参数。对比所得模态频率和模态阻尼比,以两种模态参数分析两种不同方式阻尼器的制振效果。最后以模态阻尼比和模态频率作为指标提出阻尼器的优化思路。
[Abstract]:With the development of economy and science, the bridge is developing towards the direction of large span. The cable-stayed bridge plays an increasingly important role in the modern traffic system, and the cable-stayed cable is the most important component of the cable-stayed bridge. Because the cable-stayed rigging has the characteristics of light weight, low damping and large flexibility, it is easy to produce various kinds of harmful vibration under external excitation. The vibration of cable will cause fatigue damage or even damage of cable anchoring end, which will affect the normal use of bridges. Therefore, how to effectively control the vibration of stay cables is one of the most important issues in bridge dynamics. The commonly used vibration control measures for stay cables are: traditional pneumatic measures, centralized dampers and auxiliary cables. The auxiliary cable divides the stay cable into several sections, thus improving the stiffness of the stay cable. At the same time, the cable-net system is formed by connecting the independent cable-stayed cables in the spatial structure, which improves the overall stiffness of the cable-plane. The setting of auxiliary cable can not improve the energy dissipation ability of cable net system, and the vibration control effect is still limited to some extent. Installing concentrated damping at the auxiliary cable end or at the connection between the auxiliary cable and the stay cable can increase the damping of the cable-net system, so that the damping effect of the cable net system can be greatly improved. The vibration absorption mechanism of cable-assisted cable-net system is still lack of reliable theoretical basis, especially in the selection and optimization of parameters is not perfect. In this paper, the selection of auxiliary cable parameters and the influence of different auxiliary cable parameters on the vibration control effect of cable-assisted cable-net system are analyzed by means of theoretical analysis and finite element simulation. The selection of the type of concentrated damper and the selection and optimization of location are studied. In this paper, the static and dynamic characteristics of single cable are analyzed based on the research background of the middle stay cable of Jialing River Bridge. The theoretical model of single cable is established, and a reasonable finite element simulation model is established. The finite element software ANSYS is used to simulate and analyze the dynamic characteristics of single cable. The effects of cable sag effect and damping effect on the frequency, damping ratio and vibration shape of cable are considered. Secondly, the vibration absorption mechanism of auxiliary cable is studied theoretically, and the influence of the parameters such as tension mode, installation point, cross-section area and initial tension on the dynamic characteristics of cable net structure is analyzed by finite element simulation model. Then the free vibration equation of cable-net system is established, and the vibration modes of the system are obtained by combining the boundary equation, the deformation coordination equation and the equilibrium equation of the force. The effects of the overall stiffness of the cable net and the stiffness of the damper on the modal frequency and damping ratio of the system are studied by using the approximate analytical formula. Two kinds of concentrated dampers which can be used to reduce the vibration of cable-net are proposed and the layout of dampers is determined. The simulation model is established by ANSYS software, and the modal parameters of cable-net structure with two dampers are obtained by using complex modal analysis method. Compared with the modal frequency and the modal damping ratio, the vibration suppression effects of two different dampers are analyzed with two modal parameters. Finally, the optimization idea of damper is put forward with modal damping ratio and modal frequency as indicators.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.3;U448.27

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