【作者】 姜天华；

【导师】 霍凯成；

【作者基本信息】 武汉理工大学 ， 结构工程， 2009， 博士

【摘要】 大跨度桥梁作为交通枢纽和生命线工程,近年来在全世界范围内的研究和建设方兴未艾,然而大跨度桥梁由于具有轻柔的特点,在强烈外荷载的作用下动力响应剧烈。因此,采取有效的措施来抑制大跨度桥梁结构的振动响应,并确保其在长期服役下的安全性、适用性及其耐久性具有重要的研究意义,同时也是广大工程师与科研工作者所面临的现实问题。对于桥梁结构振动响应的控制研究,目前多集中于地震和风振响应控制。本文主要研究大跨度桥梁风致振动控制。风致振动控制的措施主要有气动措施、结构措施和机械措施三种。自1940年美国旧Tacoma桥因风致振动失稳倒塌以来,利用控制措施改善桥梁气动稳定性的研究已引起极大的关注,而出于经济、方便与美观的考虑,在主梁上安装一些气动措施,是振动控制研究的重点。随机脉动风场的模拟是大跨度桥梁颤抖振时域分析的前提。谐波合成法和线性滤波器法是随机过程的Monte Carlo模拟中的传统方法,应用最为广泛。小波分析方法是Fourier分析思想的发展与延拓,能够快速、准确地提取样本的局部谱密度特征,所以它是本文研究随机风场模拟的主要内容。天兴洲长江大桥是世界上第一座四线铁路桥梁,也是世界上跨度最大的公铁两用斜拉桥。这种漂浮体系铁路桥梁在强风作用下主梁会产生大幅侧向振动,严重影响其正常使用。如何使用经济有效的减振措施来降低其风致振动幅值成为桥梁工程的主要问题之一。国内外关于桥梁竖向抖振研究的文献较多,而有关侧向抖振的研究较少,所以以天兴洲大桥作为研究背景,系统地研究该桥主梁侧向抖振响应控制也是本文研究的一个重点内容。本文主要完成了以下几方面的工作:(1)阐述了大跨度桥梁风致振动国内外研究状况,介绍了大跨度桥梁风致振动控制的几种方法,总结了针对主梁断面的几种有效的气动控制措施,证明了气动控制措施对颤振控制的有效性。(2)对苏通长江大桥闭口箱梁进行了CFD分析,提取了不同攻角下的静力三分力系数进行对比分析并通过流场的速度分布图探讨其三分力系数变化的原因。(3)全面分析了不同断面型式对静力三分力系数的影响。在上述基础上,进一步设计了46种不同宽度风嘴、不同宽度导流板、不同中央开槽宽度、不同宽高比、不同透空率栏杆的某悬索桥主梁断面,利用CFD方法分析了风嘴宽度、导流板宽度、中央开槽宽度、主梁宽高比、栏杆透空率对静力三分力系数的影响。通过各种断面对比分析,总结出了采取气动措施对大跨度桥梁静力风荷载的影响,并给出在本文设计中比较合理的断面型式。(4)将小波分析方法应用到随机风场的模拟中,实现了桥址处脉动风场的有效模拟。该方法基于多分辨率分析的思想和Meyer正交小波基,推导了小波系数与功率谱密度函数之间的关系,利用Log-Poisson湍流模型,由已知的功率谱密度函数随机生成各尺度上的小波系数,在拟合目标风速谱的同时引入湍流间歇性,进而由生成的小波系数通过逆变换生成平稳风速时程。(5)建立了天兴洲大桥三维有限元分析模型,并对其动力特性进行了分析;在此基础上,研究了MR阻尼器和流体阻尼器对漂浮体系铁路斜拉桥主梁侧向抖振响应的混合控制。建立了MR阻尼器和流体阻尼器混合控制系统对漂浮体系公铁两用斜拉桥侧向抖振响应的模糊混合控制的设计方法,并将其应用于天兴洲大桥的主梁侧向抖振响应的控制中。更多还原

【Abstract】 To be important transporting facilities and lifeline infrastructures, long-span bridges have been widely investigated and constructed across the world in recent years. Owing to their light and flexible properties, long-span bridges may vibrate excessively subjected to intensive external excitations. Therefore, it is essential to abate their strong dynamic responses for their safety, applicability and durability during long term service, which is also an actual issue for common civil engineers and researchers. As far as the vibration control of bridges is concerned, most attentions are paid to the dynamic responses subjected to wind loads or seismic excitations.The control for wind-induced vibration of long-span bridges was studied in this thesis.Control measures for wind-induced vibration have mainly aerodynamic measures, structural measures and mechanical measures. After the collapse of Tacoma Bridge which was caused by wind-induced vibration instability in 1940, much attention has been put on the research of improving the aerodynamic stability of bridge by means of control measures. Considering the factors of economic, convenience and aesthetic, aerodynamic control measures which were installed on the girder becomes the focal point in vibration control research. Simulation of stochastic wind velocity field is prerequisite to flutter or buffeting analysis of long-span bridges in time-domain. The spectral method and the filtering method are the two traditional simulation methods, which are most widely used. Wavelet analysis method is the development and extension of Fourier analysis, which can quickly and accurately extract the local spectral density characteristics of sample.So wavelet analysis method is the main content to stimulate stochastic wind velocity field.Tianxingzhou Yangtze River Bridge is the first bridge with four railway lines and is the longest span highway and railway combined cabled-stayed bridge in the world. This floating system of bridge, however, may result in large lateral dynamic responses in decks subjected to strong wind. Furthermore, it may substantially affect bridge safety and common functions. Therefore, how to use economical and effective measures to reduce wind induced finite vibration becomes one of the primary problems of bridge engineering. The domestic and foreign researchers have done plenty of research about the vertical buffeting vibration of long-span bridges. But to the lateral vibration, little research has been done. Lateral dynamic response control for long span bridge subjected to wind induced lateral buffeting has been systematically investigated in this thesis based on Tianxingzhou Bridge. The work of this thesis mainly includes the several parts as follows:(1) We first described the domestic and foreign research status of wind-induced-vibration of long-span bridges, introduced several typical methods of wind-induced-vibration control of long-span bridges, and generalized several effective aerodynamic control measures to main beam cross-section. The effectiveness of aerodynamic control measure to buffeting was proved.(2) The main girder section of Sutong Yangtze River Bridge were analysised by means of CFD method. We got coefficients of tri-component from different angles and compared the results with tunnel experimental results and explored the reasons for the changes of coefficients of tri-component through analysising fluid velocity filed.(3) A comprehensive analysis has been done about different girder sections how to affect coefficients of tri-component. On that basis, 46 main girder sections were designed which have different width guide vane, different width fairing, different central slot width, different width-depth ratio and different ventilation ratio of parapets. We have analysised the affections of guide vane width, fairing width, central slot width, width-depth ratio and ventilation ratio of parapets to coefficients of tri-component by means of CFD method. Through the comparison analysis of various sections, we generalized the influences of aerodynamic control measures to the static wind load of long-span bridges, and gave the most suitable sections which were designed in this thesis.(4) Wavelet method was applied to the simulation of the stochastic wind field, performing the effective simulation of spatial stochastic wind field. According to the idea of multi-resolution analysis and orthonormal wavelets, relationship between wavelet coefficient s and PSD(power spectral density)function is deduced , then the wavelet coefficients on each and every scale are obtained from the given PSD function,the intermittency was introduced into wavelet coefficients while at the same time preserves the target spectral characters. As a result, the inverse wavelet transform is applied to generating stationary wind velocity history through the given wavelet coefficients.(5) The three dimensional finite element model of Tianxingzhou cable-stayed Bridge is established and its dynamic characteristics are numerically investigated. Based on this, hybrid control for lateral buffeting responses in decks of floating system cable-stayed bridge installed MR dampers and fluid dampers are investigated. Hybrid control approach is developed and thereby applied for mitigating lateral dynamic responses of Tianxingzhou cable-stayed bridge in decks subjected to buffeting based on fuzzy semi-active control strategy.更多还原