Studies On Wind-induced Vibration Of Steel Bridge's Member In Mountainous City

China is a mountainous country,because of the complex land form,in mountainous cities bridge's wind-resistant design is different from that in other cities,it is not only linked to wind characteristics of mountainous cities and bridge's characteristics,but also to both interaction.The wind characteristics of mountainous cities is different from that of flat cities,there are seldom description about wind characteristics of mountainous cities in existing norms.Thus,it is necessary for mechanism of wind-induced vibration of steel arch bridge's member in mountainous cities to control a variety of harmful wind vibration about steel arch bridge's member and extend the service life of the bridge and ensure the safety of the whole bridge and ensure the traffic safety in mountainous cities,it contains theoretical value and actual meaning.With the development of modern bridge,the demands impel the bridge to toward to large span,flexible structures,light weight,that kind of structure will be more sensitive to wind loads.The members of long span steel bridge are sensitive to wind loads,and Vortex-excited vibration is easy to be induced by wind speed.Based on Chongqing Chaotianmen Bridge,the paper takes typical member as the object of study,ANSYS-FLUENT was used,a self-coded program UDF was embedded in the software by Runge-Kutta method,numerical simulation on two-dimensional member's vortex-excited vibration was done,and the main work is as follows:(1)Two-dimensional model's numerical simulation in unsteady flow field was done,existing test data and numerical data were compared with lift coefficient,drag coefficient,frequency,Strouhal data,and the accuracy of numerical simulation in static flow field was checked.(2)Average value and standard deviation of mean aerodynamic force coefficient in the two different models which are Realizable k-? and SST k-? were contrasted.Change rules of the models were analyzed,precision of the models was contrasted.At the same time,mean aerodynamic force coefficient of different wind attack angles were contrasted,range of maximum angle was analyzed.Change rules of lift coefficient and drag coefficient in different wind attack angles were summarized;Change rules of vortex-excited vibration's lock range and lift coefficient?drag coefficient were analyzed in different wind speed.(3)Second development of ANSYS-FLUENT was used,numerical simulation of square column's two-dimensional model in dynamic flow field was done,the changes of displacement's time history curve and wind speed's lock range were gotten,the change rules of mean aerodynamic force coefficient were analyzed,Flapping phenomenon of fluid-solid coupling was analyzed.(4)Runge-Kutta method was embedded in the software by the style of self-coded program UDF.Simulation on vortex-excited vibration of Chaotianmen Bridge's typical member was done.Tree influence factors including wind speed?wind attack angle?damping ratio were contrasted and analyzed,the influence of vortex-excited vibration caused by the wind speed's lock range,most disadvantaged wind attack angle and damping ratio were analyzed.When designing bridge,the wind speed?damp?wind attack angle of vortex-excited vibration should be avoided,occurring resonance and accelerating destruction speed should be avoided.