【作者】 郭翠翠；

【导师】 张海龙；

【作者基本信息】 华中科技大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 斜拉索具有质量小、刚度小、阻尼小的特点,极易在各种激励下发生横向振动,影响桥梁结构安全、使用性能与寿命。作为主要振动形式之一的参数振动,由于现代斜拉桥均采用密索体系,拉索固有频率分布广,且主梁振动的基频均较低,很容易满足其发生的条件,从而激起拉索大幅振动。这对桥梁的安全性及稳定性是个很大的冲击。因此,准确分析其振动特性并制定合理控制措施对于斜拉桥的建设和维护意义重大。本文首先介绍了斜拉索的非线性特征及拉索振动的基本概况,回顾了国内外学者在斜拉索参数振动方面所做过的主要工作,并对参数振动的机理进行了简要阐述。在综合考虑拉索的垂度效应、大变形效应、拉索与桥梁的倾角效应的基础上,建立了斜拉索轴向激励下非线性参数振动模型,具体推导出斜拉索单自由度方程。并进一步建立拉索-桥面-桥塔耦合振动模型,推导出三自由度非线性参数振动微分方程组。以武汉天兴洲长江大桥为工程背景,利用ANSYS结构分析程序建立了有限元模型,通过模态分析得到了该桥的动力特性。将前三十阶频率与全桥拉索自振频率相匹配,找出可能发生参数振动的拉索。采用龙格-库塔数值分析方法,针对拉索进行参数振动分析,研究其振动特性。详细分析了激励频率、初始索力、倾角、初始扰动、桥面及桥塔质量与刚度、阻尼对参数振动特性的影响。本文还介绍了各种拉索振动控制方法,重点针对粘弹性阻尼器,对本文所建立的耦合参数振动模型进行了振动控制分析,并提出实际工程中的应用方法。更多还原

【Abstract】 Due to the small rigidity, small mass and low damping, cables in cable-stayed bridge are prone to exhibit transverse oscillations of large amplitude which may affect the safety of the whole bridge, reduce the service performance and life. Usually, the multi-cable systems are extensively used in modern cable-stayed bridges, the natural frequencies of cables have a wide distribution and the basic frequencies of girders are lower. As a result, the parametric vibration, one of the kinds of cable vibrations, may provoke large amplitude and impact on the safety and stability of bridges as the occurrence conditions are met easily. Therefore, accurate investigation of vibration characteristics and rational countermeasures are very important for construction and maintenance of cable-stayed bridges.At the first chapter of the paper, the nonlinear characteristics and general situation of cable vibration are introduced, the major works that the domestic and the foreign scholars have done in the field of parametric vibration are reviewed, and the mechanism related are briefly analyzed. Based on the comprehensive effect of sag, large deformation and inclination, the nonlinear model of parametric vibration in axial motivation is built and the single-degree-of-freedom equation is deduced. Furthermore, the cable-girder-tower coupling vibration model is built and the three-degree-of-freedom nonlinear parametric vibration differential equations are gained. The paper sets Tianxinzhou Bridge as the project background and the ANSYS structural analysis procedures are used to develop the dynamic calculation model. Then the dynamic properties are obtained through modal analysis. Comparing the first thirty frequencies of the model with the natural frequencies of cables, the cables that may exhibit parametric vibration were found. The characteristics of vibration are analyzed by Runge-kutta numerical analysis method. The influence of the various parameters, such as excitation frequency, the initial force of cables, the inclination, the initial disturbances, the mass and the stiffness of girder and tower and so on, are investigated.In addition, the vibration controlling measures are introduced. The coupling vibration model proposed in this paper was used to analyze the effectiveness of the viscoelastic damper employed in vibration controlling measures. At last, the practical controlling methods are presented.更多还原