Nonlinear Three-Dimensional Coupling Vibration Of Wind-Vehicle-Bridge System

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.