【作者】 李永乐；

【导师】 强士中；

【作者基本信息】 西南交通大学 ， 桥梁及隧道工程， 2003， 博士

【摘要】 本文将风、车、桥三者作为一个交互作用、协调工作的耦合振动系统，较全面地考虑了风桥间的流固耦合作用、车桥间的固体接触耦合作用、风对车的空间脉动作用及整个系统的时变特性。 首先，基于自由振动信号，提出了一种颤振导数识别的新方法——加权整体最小二乘法(WELS)，以识别桥道断面的颤振导数。为考虑斜拉桥桥塔风效应，根据大跨度斜拉桥结构形式特点，结合脉动风的相关特性，提出了一种简化的大跨度斜拉桥三维脉动风场模拟方法。针对桥址区风速观测记录的特点，证明了利用不同高度处月最大风速记录推算地表粗糙度影响系数的可行性，并对通过最小二乘拟合得到的地表粗糙度影响系数进行统计分析，最终确定桥址区风特性。采用研制的三分力分离装置——交叉滑槽系统(Crossed Slot System)对车—桥系统的气动特性进行了测试，得到了考虑车桥气动相互影响的三分力系数。基于测试的气动参数和模拟的脉动风速场，给出了车辆和桥梁静风力、抖振力及自激力的时域表达式。 其次，基于欧洲低干谱，模拟了轨道不平顺样本。建立了轮轨接触几何和轮轨接触力的迭代算法。在分析车—桥系统的几何耦合关系和力学耦合关系的基础上，建立了风—车—桥系统运动方程，通过分离平衡迭代方法进行求解，并考虑非线性因素的影响。基于本文的分析理论及多年的科研积累，采用Visual C++的Windows编程技术，编制了桥梁结构科研分析软件BANSYS(Bridge ANalysis SYStem)。 最后，以京沪高速铁路南京长江大桥为工程背景，比较了桥梁时域抖振分析和频域抖振分析的一致性，分析了桥塔风效应和非线性因素对结构抖振响应的影响。针对风—车—桥系统振动特点，提出了一种更能反映桥梁实际振动特性的评价指标表达式。采用BANSYS软件对风—车—桥系统的振动特性以及风场模型、风速、车速、车辆位置及非线性等因素的影响进行了多工况的对比分析。 时域抖振分析结果表明：大跨度斜拉桥抖振的时域和频域分析方法具有较好的一致性；考虑桥塔风效应会显著增大桥塔的横桥向抖振响应；非线性因素会降低斜拉桥的自振频率，会增大斜拉桥的竖向及扭转抖振响应。 风—车—桥系统耦合振动分析结果表明：考虑风的作用会显著增加车辆和桥梁的响应；车辆和桥梁的响应总体上随风速和车速的提高而变大；车辆位于桥道背风侧时较迎风侧时更为不利；非线性因素对桥梁的影响较车辆的要大。更多还原

【Abstract】 In this dissertation, wind, vehicle and bridge are regarded as an interactional coupling vibration system., In the analysis model of the system, many factors are considered in detail, such as the fluid-solid coupling interaction between wind and bridge, the solid contact coupling interaction between vehicle and bridge, the stochastic wind load of vehicle, the time variation characteristic of the system induced by train movement.Firstly, a reliable but simple identification method, here called the Weighting Ensemble Least-Square method (WELS), has been developed to extract all eight flutter derivatives of bridge deck from free vibration records. According to the properties of both the structural style and the vibration mode of long cable-stayed bridge, and considering the correlation characteristics of natural wind, a practical method is introduced to simplify stochastic wind velocity field of long cable-stayed bridges for taking pylon wind field effect into account. Based on wind speed observation record with drawback, it is proved that the exponent expressing terrain roughness can be calculated according the monthly maximum wind speed records at various height levels. Wind characteristics of bridge site are determined by statistical method. In order to measure respective aerodynamic parameters of deck and vechile when vehicle is above deck, a simple but performance- excellent device was developed, here called Crossed Slot System. The device can separate the wind loads on bridge and on vehicles from each other. Based measured aerodynamic parameter and simulated wind speed field, time-domain expression of static wind load, buffeting load and self-excited load for bridge and vehicle are introduced.Secondly, Germany high-speed spectrums with weak disturbance are adopted to simulate the stochastic rail irregularities. Iterative methods are developed to calculate the geometric relationship and interaction force between wheel and rail. Based the geometric and mechanical coupling relation between vehicle and bridge, movement equation of wind-vehicle-bridge system is established. The equation can be solved by a separated iterative procedure which can considers various nonlinear factors. According to the theory presented in this dissertation and author’s research practice for many years, a computational software, named BANSYS (Bridge Analysis System), is developed by the Windows technique of Visual C++.Finally, Nanjing Yangtze River Bridge on Peking-Shanghai high speed railway which is a three-pylon cable-stayed bridge is analyzed. In buffeting analysis, analysis result in timedomain is compared with that in frequency domain. The effects of pylon wind speed field and nonlinear factors are taken into account. In wind-vehicle-bridge system vibration analysis, The effects of wind field model, wind speed, train speed, relative location of vehicle and nonlinear factors on the system vibration are analyzed by various case comparisons.It is showed in buffeting analysis that the analysis results in time domain agree well with those in frequency domain. Effect of pylon wind field can increase the lateral buffeting response of pylon. Nonlinear factor can decrease the nature frequency of cable-stayed bridge, and can increase the vertical and torsional buffeting response.It is showed in wind-vehicle-bridge system vibration analysis that cross wind action can remarkably increase the response of bridge and vehicle. Generally, the response of bridge and vehicle are increased with wind speed and train speed, one case that vehicle is on leeward side of deck is more unsafe than another case that vehicle is on windward side of deck. Nonlinear factors can more influence bridge than vehicle.更多还原