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大跨度悬索桥风致抖振时域分析与涡振性能研究

Time-Domain Analysis of Wind-Induced Buffeting and Vortex-Induced Vibration Performance Research for Long-Span Suspension Bridge

【作者】 李宁

【导师】 郑史雄;

【作者基本信息】 西南交通大学 , 桥梁与隧道工程, 2013, 硕士

【摘要】 伴随着科技革命带给我们新的建筑理念以及材料的进步,现代桥梁向大跨度、轻柔、纤细的方向发展,导致了风致敏感性的增加。在所有风引起的动力作用下的振动中,又以抖振与涡激振动比较常见,因其是在低风速下容易发生的风致振动。在对本悬索桥进行抖振分析时,采用了时域分析方法,而放弃了频域分析方法。因悬索桥几何与气动非线性都比较明显,采用时域分析方法可以反应抖振响应的时间历程。由于涡激振动现在没有完善的理论解,本文借助风洞试验通过改变桥梁断面的气动外形找到了抑制涡振的有效措施。本课题的研究是以某悬索桥为工程实例,对其进行了成桥状态时域抖振分析和涡振分析。是在计算机编程、有限元分析、风洞试验的基础上完成的。主要内容有:(1)、根据此悬索桥构造形式,将桥梁所在场地的三维脉动风场给予适当简化,基于此用谐波合成法模拟出了此桥三维脉动风场。(2)、采用ANSYS有限元软件,建立了某悬索桥有限元模型,对此桥进行了动力特性分析。(3)、对静风荷载、抖振力荷载和自激力荷载进行时域化处理。采用Scanlan的准定常气动力理论计算抖振力,自激力是采用ANSYS中的Matrix27号单元来实现,对准定常气动力模型,先用双泰勒展开,导出的单元气动阻尼矩阵和气动刚度矩阵与自激力等价。考虑气动导纳的影响时,采用Liepmann提出的平板气动导纳函数来近似计算。本文还在此基础上探讨了风速、风攻角的变化影响成桥状态抖振响应的情况。(4)、通过风洞试验确定此桥存在涡振,并且进一步通过试验研究出抑制此桥涡振的有效措施。(5)、总结本文对悬索桥抖振与涡振的研究,有一定的工程参考价值,并且指出了需要进一步有待解决的问题。

【Abstract】 With the revolution of science and technology to bring us new architectural concept and material progress,modern bridge is developing into the longspan、flexible、slender phase,which bring about the increase of wind-induced sensitivity. In all the vibration under the dynamic action caused by the wind,again with buffeting and vortex-induced vibration are more common,because they are likely to happen under the wind induced vibration of the low speed. On the analysis of the buffeting for this suspension bridges, use the time domain method, and give up the frequency domain analysis method. Because of geometry and aerodynamic force nonlinear are obvious for suspension bridge, the analysis of time domain method can reaction time history of buffeting response. Because of vortex-induced vibrations now has no perfect theoretical solution, this paper makes use of the wind tunnel test by changing the bridge sections of aerodynamic configuration found the effective measures to restrain vortex-induced vibration.In this thesis,taking a suspension bridge as a project example,time-domain buffeting analysis at using stage and vortex analysis is studied.It is done on the basis of computer programing、 finite element analysis and wind tunnel test.The research is mainly focused on the following aspects:(1).Acoording to the properties of both the structural style of long-span suspension bridge and the wind field characteristics,a practical method is introduced to simplify three dimensional stochastic wind velocity field, and on this basis simulate the fluctuating wind field for this bridge with harmonic synthesis simulates.(2).Establish a finite element model of this suspension bridges by using the finite element program ANSYS,then analyse the dynamic characteristics.(3).The static wind load、buffeting force and self-excited force are converted to the time-domain form The buffeting force is calculated based on the quasi-steady aerodynamic force theory proposed by Scanlan. The self-excited forces are input in ANSYS through Matrix27,by applying two-variable Taylor expansion to the quasi-steady aerodynamic force model,the12-order element aerodyamic damping matrix and aerodynamic stiffness matrix equivalent to self-excited force order are derived. Using the plate aerodynamic admittances function. to consider the influence of aerodynamic admittance function. The paper also considerthe influence of buffeting response under different wind speed、different wind angle of attack to bridge.(4). Through the wind tunnel test to determine this bridge exist vortex vibration, further research out the effective suppression measures for this bridge vortex-induced vibration through the wind tunnel test.(5). The research work done in this thesis is analysed and summarized, has the certain reference value in the project of similar problems, furthermore points out the problems need to be solved in further research.

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