【作者】 王承启；

【导师】 李正良；

【作者基本信息】 重庆大学 ， 结构工程， 2011， 博士

【摘要】 大跨钢桁架拱桥是风敏感型结构体系,风荷载是此类型拱桥设计的控制荷载之一。重庆朝天门长江大桥为此类桥梁的典型案例,本文以其为对象,通过风洞试验和数值模拟对大跨度钢桁架拱桥的相关的风致振动问题展开了研究,主要包括以下几方面内容:①通过节段模型风洞试验为大跨桁架拱桥文章后面的抖振提供数据。在气弹模型风洞试验过程前,对桥址风环境进行了风洞试验模拟。②针对大跨钢桁拱桥全桥气弹模型风洞试验要求和其本身的受力特点,提出了采用变截面单根梁等效模拟大跨钢桁架拱桥的空间变截面桁架拱段的方案。并基于此方案,建立了等效单根梁有限元模型,经动力特性计算后,对比得知该等效模型与全桥仿真有限元模型结果一致。③基于等效单根梁有限元模型,在大跨钢桁架拱桥全桥气弹模型设计中提出了采用变截面工字型芯梁模拟桥拱刚度并合理简化外衣的方案。该方案能够较准确的模拟结构气动外形和刚度系统,从而使得全桥气弹模型设计切实可行。通过动力特性试验检验,表明大跨度钢桁架拱桥全桥气弹模型设计方案是正确的。④全桥气弹模型风洞试验中,分别测量均匀流和湍流中,桥梁各个工况各个风偏角下的风振响应。编程处理了试验数据,并根据数据分析研究了该桥的抗风性能。⑤针对大跨度钢桁架拱桥的特点,采用谐波合成法模拟了大跨度钢桁架拱桥的空间三维风场,且进行了时域抖振分析。其结果与试验值吻合。⑥为考虑流固耦合作用,将振动方程的数值方法Runge-Kutta法代码嵌入FLUENT软件中,使之可以进行涡激振动仿真计算。建立二维平面流固耦合,对大跨钢桁架拱桥典型杆件涡激振动进行计算分析。系统对比研究了结构自由度、阻尼比、风偏角、前杆干扰对杆件涡激振动影响。⑦以ANSYSWORKBENCH为平台,对大跨度钢桁架拱桥的吊索进行合理流固耦合分析计算。首先对圆截面的吊索进行分析,建立了计算模型,采用层流模型与k-ω湍流模型对比计算,分析研究了节点位移时程曲线及索表面点风压时程曲线等风振响应特性。然后对两并列吊索及两串列吊索进行了流固耦合风振响应分析。更多还原

【Abstract】 The long span seel tussed ach bridge is the wind-sensitive structural systems. Wind load is one of control loads for designing. Chongqing Chaotianmen Yangtze River Bridge is a typical case of this kind of arch. It is the object to be researched in this paper. By means of wind tunnel tests and numerical simulation, the wind-induced responses of the kind of bridge are studied, including the following aspects:①The data provided for the bridge buffeting were obtained in section model wind tunnel test. The wind-environment on the bridge site was simulated in wind tunnel tests before the process of aeroelastic-model wind tunnel test.②In order to meet the requirements of the force features and full aeroelastic model wind tunnel test for the kind of bridge, the method is proposed, which is that a single beam of variable cross-section simulates the truss arch of variable cross-section. Based on the method, the equivalent single-beam finite element model was established. Their dynamic behaviors of the models show that the equivalent finite element is consistent with the full-bridge model.③Based on single-beam finite element model, during the design of the whole aeroelastic model for the long span steel truss arch bridge, the variable cross-section“工”shaped core simulates the stiffness of the arch and the coat section is simplified in reasonable way. The method makes full-bridge aeroelastic model design feasible, the structure can be accurately simulated in the aspects of aerodynamic shape and the system stiffness. The results of dynamic characteristic test show that design of full-bridge aeroelastic model for the long span steel truss arch bridge is correct.④During the full-bridge aeroelastic model wind tunnel tests, the wind-induced response of the bridge were measured under the conditions such as the uniform flow and turbulence, all bridge stages, various wind yaw angles. The experiment data were analyzed by programming. Base on the data, wind-resistant behaviors of the bridge was analysed.⑤Based on the characteristics of the long-span steel truss bridge, the harmonic synthesis method are adopted to simulate three-dimensional wind field of the long-span steel truss bridge, and the time domain buffeting was analysed. The results were agreement with the experimental results. ⑥Considering fluid and solid coupling, the vibration equation method Runge-Kutta numerical method code were embedded in FLUENT software, and then the vortex-induced vibration (VIV) can be simulated. The two-dimensional fluid-structure interaction model was built and the VIV of the typical bar of the long span steel truss bridge aer calculated. The factors such as degree of freedom, damping ratio, wind angle, the former bar of disturbance are studied on the VIV.⑦Based on the platform of ANSYS WORKBENCH, the reasonable calculation of FSI for the bridge cable was carried out. At first, the FSI of the circular cross-section cable was analysis. The computational models were the established. The laminar flow model and the k-ωturbulence model were compared in calculations. The features of wind-induded vibration are analysed, such as the time-history of displacement and the cable surface pressure. Then, the FIS of two cable in parallel and serial were studied in wind vibration response.更多还原