【作者】 王志强；

【导师】 廖海黎；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2011， 硕士

【摘要】 伴随着材料和施工工艺的发展,新的桥梁结构设计方法已经基本可以避免结构气动失稳的发生。但是,随着桥梁跨度的增加,结构将变得更加轻柔,阻尼更小,质量更轻,这些因素导致了结构对风的敏感性不断增强,结构的风致响应问题变得更加突出。抖振是一种紊流风引起的振动形式,抖振具有在任何风速下都发生的特点。当结构处于施工阶段时,结构刚度较小,抖振可以诱发结构较大的振动,因此,有必要研究施工阶段桥梁的抖振响应。本文以铁路斜拉桥施工阶段的抖振响应为研究对象,主要工作包括以下几个方面：(1)建立了一种简化的斜拉桥三维随机风场模型,并使用谐波合成法编制了相应的风场模拟程序。(2)在结构动力特性计算方面,介绍了钢桁架加劲梁的建模方法；根据刚度和质量等效的原则,建立了单主梁模型来简化模拟整体桁架加劲梁,这种简化模型对后续的风振响应计算非常方便。(3)以Scanlan抖振理论为基础,对静风荷载和抖振力荷载进行了时域化处理,并采用数值积分方法对动力平衡方程进行了逐步求解,获得了结构的抖振响应；开发了抖振分析通用程序。(4)以某铁路斜拉桥的施工阶段为工程背景,详细介绍了节段模型风洞试验和全桥模型风洞试验的内容,并对桥梁的抖振响应进行了测量；采用自己编制的抖振分析程序对该斜拉桥的抖振响应进行了计算分析,对比研究了气动导纳函数及桥塔所受的风荷载对结构抖振响应计算结果的影响。通过对比理论计算结果和风洞试验结果,可以发现：理论计算结果和风洞试验结果变化趋势基本一致；风洞试验的试验值基本处于气动导纳取1和取Sears函数的计算值之间,因此理论分析时应该偏安全地采用气动导纳取1进行计算；考虑桥塔的风效应会更加精确地获得桥塔的横桥向抖振响应；风场相关性函数模型、模拟的风速样本以及计算精度都会影响计算分析的精度。更多还原

【Abstract】 With the development of material and construction technology, by using new structural design method the aerodynamic instability of structures could be avoided. But when the span of bridge is becoming longer and longer, the bridge would exhibit some special characteristics such as high flexibility, low structural damping and light in weight; Those characteristics make the structures more susceptible to wind loads and elevate the possibility of wind-induced vibration. Buffeting is a kind of vibration induced by turbulent winds, it can occur at any wind speed. During the construction stage, the whole stiffness of bridge is not large, so excessively large vibration can be excited by buffeting, in this way it is very necessary to study the buffeting response of bridge under construction stage.In this thesis, the buffeting response of the railway bridges under construction is investigated. The main work of this paper is listed as follows:(1) A simplified three-dimensional stochastic wind velocity field model is established in this paper; also the constant amplitude wave superposition is employed to simulate the stochastic wind velocity.(2) As for the calculation of structural natural dynamic behavior, the modeling method for the steel truss stiffened girder is discussed. According to the principle of equivalent rigidity and equivalent mass, a single beam model is built to simulate the whole truss stiffened girder; This simplification is necessary for the analytical process.(3) Based on the buffeting theory proposed by Scanlan, the wind loads which include steady-state wind loads and buffeting loads are converted into time domain description. Then the numerical integration algorithm is used to calculate the equation of motion, so the buffeting response could be obtained. A universal program is developed for buffeting response analysis.(4) A railway bridge under construction is taken as a case study, and the sectional model test and full aeroelastic bridge model wind tunnel test are introduced in details. The buffeting response of the bridge is measured in wind tunnel. Different influences on the buffeting response that take into account aerodynamic admittance function and wind loads acting on the pylon are calculated by using self—developed program.Comparing the results obtained through wind tunnel and the results by theory calculation, some conclusions can be drawn. The wind tunnel results generally comply with the calculation results. The wind tunnel results are smaller than the calculation results when the value of the aerodynamic admittance is set to 1 but are larger than the calculation results when the value of the aerodynamic admittance is replaced by Sears function, so in light of this, for purpose of safety it is necessary to employ the calculation results that are obtained by adopting 1 as aerodynamic admittance to evaluate the buffeting response of cable-stayed bridges. The lateral response of the pylon can be accurately obtained when the loads acting on the pylon are taken into account for calculation. Model for the wind field coherence function, sample of simulated wind speed velocity, calculation accuracy all have significant influence on the accuracy of calculation and analysis.更多还原