Time-Domain Analysis Of Wind-Induced Buffeting And Vortex-Induced Vibration Performance Research For Long-Span Suspension Bridge

With the revolution of science and technology to bring us new architectural concept and material progress,modern bridge is developing into the longspan、flexible、slender phase,which bring about the increase of wind-induced sensitivity. In all the vibration under the dynamic action caused by the wind,again with buffeting and vortex-induced vibration are more common,because they are likely to happen under the wind induced vibration of the low speed. On the analysis of the buffeting for this suspension bridges, use the time domain method, and give up the frequency domain analysis method. Because of geometry and aerodynamic force nonlinear are obvious for suspension bridge, the analysis of time domain method can reaction time history of buffeting response. Because of vortex-induced vibrations now has no perfect theoretical solution, this paper makes use of the wind tunnel test by changing the bridge sections of aerodynamic configuration found the effective measures to restrain vortex-induced vibration.In this thesis,taking a suspension bridge as a project example,time-domain buffeting analysis at using stage and vortex analysis is studied.It is done on the basis of computer programing、 finite element analysis and wind tunnel test.The research is mainly focused on the following aspects:(1).Acoording to the properties of both the structural style of long-span suspension bridge and the wind field characteristics,a practical method is introduced to simplify three dimensional stochastic wind velocity field, and on this basis simulate the fluctuating wind field for this bridge with harmonic synthesis simulates.(2).Establish a finite element model of this suspension bridges by using the finite element program ANSYS,then analyse the dynamic characteristics.(3).The static wind load、buffeting force and self-excited force are converted to the time-domain form The buffeting force is calculated based on the quasi-steady aerodynamic force theory proposed by Scanlan. The self-excited forces are input in ANSYS through Matrix27,by applying two-variable Taylor expansion to the quasi-steady aerodynamic force model,the12-order element aerodyamic damping matrix and aerodynamic stiffness matrix equivalent to self-excited force order are derived. Using the plate aerodynamic admittances function. to consider the influence of aerodynamic admittance function. The paper also considerthe influence of buffeting response under different wind speed、different wind angle of attack to bridge.(4). Through the wind tunnel test to determine this bridge exist vortex vibration, further research out the effective suppression measures for this bridge vortex-induced vibration through the wind tunnel test.(5). The research work done in this thesis is analysed and summarized, has the certain reference value in the project of similar problems, furthermore points out the problems need to be solved in further research.