Investigation On Pylon Galloping And Main Girder Vortex-induced Vibration Of Single-pylon Cable-stayed Bridge

With the development of new construction materials and bridge construction techniques,the long-span suspension bridge and cable-stayed bridge are developing rapidly all over the world.For long-span bridge,the relative stiffness of main girder become smaller,natural frequency and damping become also lower, which make bridge becomes more sensitive to wind load, and wind-induced vibration also become more and more prominent.And therefore, galloping and vortex-induced vibration (VIV), assumed as the main research contents of the bridge wind-induced response, attract more and more attention of bridge engineering.In this thesis, a single-pylon cable-stayed bridge as research background is taken to analyze the galloping stability and the vortex-induced vibration performance of self-supporting pylon state, vortex-induced vibration quality of main girder is also analyzed by wind tunnel mode test.The major work is shown as follows:(1).The simplified model of the single-pylon cable-stayed bridge is built with ANSYS to perform modal analysis of self-supporting pylon state, the maximum double cantilever state and finished dead state.(2).Generating mechanism of galloping based on Quasi-Steady Theory is analyzed, and this paper expounds the galloping is caused by the negative slope effect of lift curve.(3).Two methods to calculate the galloping critical wind speed of pylon structure are introduced and compared by utilizing an engineering example and static force coefficients simulated outcome based on CFD of pylon to calculate two galloping critical wind speed formulae to judge which one is better.(4).In order to research influence of aerodynamic shape of pylon section on galloping critical wind speed and vortex-induced vibration performance, the main section of the pylon as the research object is chosen to discuss galloping stability and vortex-induced vibration performance of pylon by changing the aerodynamic shape of cross section in this thesis.(5).Vortex-induced vibration performance of main girder is researched by wind tunnel test, and further, effective measures to restrain bridge vortex vibration are worked out.(6).On the basis of the result of this thesis, some valuable references to practical engineering are concluded.