【作者】 陈宁；

【导师】 李永乐；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2015， 博士

【摘要】 强风不仅会加剧桥梁的振动,降低结构的疲劳寿命和耐久性,还会使桥上通行车辆产生安全性和舒适性问题。为减少大风灾害天气中桥上交通事故的发生,沿桥面设置风屏障已成为保障车辆行驶安全性的有效措施之一。本文基于风—汽车—桥梁系统耦合振动分析理论,围绕桥上车辆的行驶安全性和舒适性及风屏障的影响问题,开展了如下主要研究工作：(1)提出了基于IFFT变换技术的一维多变量平稳随机风场模拟方法。该方法利用共轭对称序列逆傅立叶变换(IFFT)相位角为零的特性,在频域构造复共轭序列,通过一次IFFT变换直接生成单点脉动风速时程。该方法不仅消除了三角函数叠加的运算工作量,同时极大的减少了IFFT执行的次数,使得模拟方法的计算效率更高。数学分析表明,随机样本的均值和自相关函数满足各态历经性；样本周期足够长时,互相关函数同样满足各态历经性。(2)建立了风—汽车—桥梁系统的耦合振动分析模型。根据典型的公路车辆类型,建立了13个自由度的两轴车辆和24个独立自由度的四轴拖挂车辆动力学分析模型,论述了轮胎偏转特性对车辆动力学方程的影响。阐述了汽车、桥梁相互作用原理。根据随机路面激励的相干函数模型,基于IFFT变换方法,提出了一种考虑相干函数模型的路面不平度时域样本模拟方法。探讨了风对桥梁的气动力作用,考虑到移动车辆的运动特性及自然风环境中水平和竖向脉动风对移动车辆瞬态风偏角和风攻角的影响,推导了适用于移动车辆三维绕流特性的精细化气动力表达式,能较为真实的反映公路移动车辆所受的风荷载。在此基础上,建立了风—汽车—桥梁系统的耦合振动分析方程。(3)编制了风—汽车—桥梁系统耦合振动分析程序。基于MFC程序设计框架和OpenGL三维显示技术,在Visual Studio 9.0平台上编制了风—汽车—桥梁耦合振动分析程序WVBANSYS,分别验证了车—桥耦合程序,桥梁时域颤振分析程序,时域抖振分析程序,从而间接验证了风—汽车—桥梁程序计算功能的正确性和可靠性。(4)研究了风—汽车—桥梁耦合振动系统动力响应的影响因素和变化规律。基于车辆的响应特性,改进了风致车辆侧倾和侧滑事故的评价标准,探讨了基于ISO 2631标准的行车舒适性评价准则。围绕侧风环境下公路车辆的行驶安全性和舒适性问题,可得如下结论：气动力风偏角导数dC/dψ降低了车辆行驶的安全性和舒适性,轮胎侧偏特性降低了车辆行驶舒适性评价指标；路面不平度相干函数差异导致车辆的动力响应产生较为显著的差异。风速和车速较高、车辆位于迎风侧车道和道路状况较差,这些因素会降低车辆的安全性和舒适性指标。(5)研究了风屏障对桥面局部风环境和车辆行驶安全性的影响。在风洞试验中研究了风屏障透风率对桥面流场平均风速和平均湍流强度分布特性以及不同类型公路车辆气动力特性的影响。试验结果表明,风屏障降低了桥面平均风速和湍流强度,有效地降低了车辆所受的气动力大小。静力简化分析和耦合动力分析结果表明,无风屏障时大型集装箱车最容易发生侧倾和侧滑安全事故；风屏障显著地提高了车辆安全行驶的临界风速,且车辆的行驶临界风速随风屏障透风率的降低逐渐提高。更多还原

【Abstract】 Strong winds not only intensify the vibration of bridges, reduce the fatigue life and durability of the structure, but also threaten the safety and comfort of vehicles traveling on the bridge. To lessenthe number of wind-induced traffic accidents occurred on bridgesin windy weather,the universal practice is to install wind barriers along the bridge decks, which has become one of the effectivecountermeasures to guarantee the vehicle safety. Based on the coupling vibration theory of the wind-vehicle-bridge system, this paper focuses on the issues of the sheltering efficiency of wind barriers,and the safety and comfort of vehicles traveling onbridges.Main research works are as follows:(1) A simulation algorithm of one-dimensionmultivariate stochastic wind velocity field is proposed based on inverse fast Fourier transform (IFFT). Since the phase of the IFFT for a conjugate-symmetric sequence is zero, a conjugate-symmetric series can be created in the frequency-domain. The fluctuating wind velocity for one point can be generated by just one execution of IFFT, which not only releases the computational work from enormous superposition of trigonometric operation but also decreases the executions of IFFT. So, the algorithm is very efficient. Mathematical analysis shows that the ergodic property of the mean value and the auto-correlation function of the simulated sample are satisfied, and the ergodicity of the cross-correlation function can also be satisfied as long as the period of the sample is long enough.(2) The coupling vibration model of the wind-road vehicle-bridge system is established. According on the typical types of road vehicles, the dynamic analysis models, a two-axle vehicle with 13 degrees of freedom and a four-axle trailing truck with 24 independent degrees of freedom, are set up. The effects of the deflection characteristics of tires on the dynamics equations of vehicle are disscussed. The principle of the interaction between vehicles and bridges is clarified. In consideration of the coherence functionmodel of the stochastic road surface excitation, a simulation method of the road roughness samples in the time-domain is presentedbased on the IFFTtechnique. Considering the moving property of the vehicle and the influences of the horizontal and vertical turbulence wind on the transient yaw angle and attack angle of the moving vehicle, the expressions of aerodynamic forces on road vehicles are deduced, which can correctly reflect the wind loads acting on the moving road vehicles. On the basis of the above discussions, the analytical equations of the coupling vibration of the wind-road vehicle-bridge system are established.(3) An analysis program of wind-road vehicle-bridge system is compiled. Based on the programming framework of MFC and the 3D display technology of OpenGL, the coupling vibration analysis program of wind-road vehicle-bridge system, named as WVBANSYS, is compiled on the platform of Visual Studio 9.0. The calculation functions of the program, including the coupling analysis of vehicle-bridge system, the time-domain flutter analysis of bridge and the time-domain buffeting analysis of bridge, are verified respectively.(4) The affecting factors and the variation rules of the dynamic response of the wind-road vehicle-bridge the coupling vibration system are investigated. Based on the response characteristics of vehicles, the judging criteria for the wind-induced sideslip and roll-over accidents are improved.The evaluation criteria of vehicle ride comfort on the basis of theISO 2631 specification is also disscussed. To focus on the issues of the safety and comfort of the driving vehicles under crosswind, some conclusions are drawn:Thederivative of the aerodynamic yaw angle dC/dy/decreases the safety and comfort of the driving vehicles, and it is in favor of the evaluation of the comfort of vehicles taken into account the effects of the deflection characteristics of tires; the differences between the coherence functions of road roughness lead to remarkable differences of the dynamic responses of vehicles; The unfavorable factors, including high wind velocity and vehicle speed, the location of the vehicle in the windward side and poor road conditions, could decrease the safety and comfort indicatorvalues of road vehicles.(5) The effects of wind barriers on the local wind environment of the bridge deck and the driving safety of vehicles are studied. In the wind tunnel, the ventilation ratios of wind barrier on the distribution characteristics of the mean wind velocity and turbulence intensity above the bridge deck are investigated. The influences of the ventilation ratios of wind barrier on the aerodynamic characteristics ofvarious road vehicles are also investigated. Results show that wind barriers decrease the mean velocity and the turbulence intensity of the bridge deck and obviously reduce the magnitudes of the aerodynamic forces acting on vehicles. The critical wind velocity for the safety of vehicles under crosswind is presented by means of the simplified static analysis and the coupling vibration analysis method.Results show that the large container truck is more prone to roll-over accidents in the absence of wind barriers; wind barriers significantly improve the critical wind speed of vehicles; the critical wind speed of vehicles increases with the decreasing of the ventilation ratios of wind barriers.更多还原