Investigation Of Long-Span Bridge Girder Spanwise Vortex-Induced Vibration

This thesis reviews the method of Vortex-Induced Vibration(VIV) research of long span bridge girder. The characteristics of two- and three- dimensional vortex shedding of bluff bodies are introduced. And the main factors are discussed which influence vortex shedding characteristics and VIV response of bluff girder. Several representative semi-empirical models, which are used to describe VIV of long span bridge girder, are introduced in detail. Based on wind tunnel test and theory analysis, the system is deduced to describe VIV response and vortex shedding force of long span bridge girder. And the methods are discussed to identify vortex shedding force in section model test. The main research contents of this thesis are shown below:1. The review and summarize of VIV research developing course and actuality.2. Classic vortex shedding characteristics of two- and three- dimensional bluff bodies are introduced to provide theoretical and experimental foundation on VIV response of long span bridge girder.3. Discussion is made here to show the effect of several main influence factors of VIV response of long span bridge girder such as Reynolds number effect, turbulent characteristics( turbulence intensity and turbulence scale), aerodynamic shape(ratio of width and height, wind attack angle and affixation aerodynamic device), Scruton number and so on.4. The semi-empirical models are introduced to describe one- and two-dimensional VIV response of bluff girder. And the first order approximate theoretical solution is deduced to describe the vertical and torsional VIV response based on empirical linear model, Scanlan's nonlinear model and Larsen's general model.5. The methods are discussed to identify Vortex shedding force of single degree of freedom models. I.e. Taking Jiang Jin Guan Yinyan Yangtse river bridge as an example, the vortex shedding force of girder at full bridge state and erection state is identified by section model test. 6. Considering influence of spanwise vortex shedding force correlation and model shape, the system is deduced to describe spanwise vertical and torsional VIV response of girder by using single degree of freedom models.7. The method is researched to identify vortex shedding force by section model test. The more accurate vortex shedding force can be obtained after considering the spanwise vortex shedding force correlation in section model tet.8. A taut strip model of box girder is designed to test spanwise VIV response, and get the vortex induced force correlation effect function.