Numerical Simulation Study Of Wind-induced Vibration Of Long-span Bridges

Bridge is today in the atmospheric boundary layer of the earth's surface buildings,inevitably affected by the effect of the wind,flow with the light-duty to bridge structure form,has a long development,bridge into a flexible system in the structure,role is very sensitive to the wind wind resistance design of bridge has become one of the key issues in bridge design.Because of the difficulty of the turbulence solution,the effect of wind on the bridge can only be measured by wind tunnel test.Wind tunnel test is not widely applied to practical engineering due to its long period and high cost.In recent years,due to the CFD(Computational Fluid Dynamics)in dealing with complex problems when the amount of time and economic cost huge superiority compared with wind tunnel test,CFD in has been more and more used in bridge wind engineering,CFD method is adopted to improve the aerodynamic characteristics of the large span bridge cross section analysis is bridge wind resistance in recent years a new field,it is the wind resistant design for long-span Bridges provides a convenient means of technology.In this paper,CFD technology is used to simulate two typical bridge structures in a two-dimensional flow field,and the aerodynamic parameters and flow field characteristics are obtained.The specific contents are as follows:(1)the research status of wind-induced vibration and the application status of CFD technology in bridge wind engineering field are summarized,and the theoretical basis of CFD technology is briefly introduced.(2),respectively,for an ideal tablet,streamlined profile and blunt section has carried on the numerical simulation of the static of three component of the ideal flat coefficient compared with the theoretical value,and the results show that the numerical results match degree is high,show that CFD method to study the reliability of the approximate stationary flow field problems.Then the variation law of the static force coefficient of the two kinds of Bridges is studied.(3)introduction to classical flutter derivative theory,using the techniques of dynamic grid ideal tablet,streamlined profile and blunt section for numerical simulation of single degree of freedom forced vibration reduction wind velocity as variables,calculate eight flutter derivatives,will be the ideal flat,comparing the numerical results with the theoretical value and experimental value to verify the reliability of the unsteady problem;(4)parametric analysis of the derivative of the section flutter was carried out to study the influence of the amplitude of the flow wind attack Angle and simple harmonic vibration on the derivative of flutter.This paper points out the nonlinear characteristics of the aerodynamic self-excitation force of the bridge section,and obtains the percentage of each order component of the aerodynamic self-excitation force through the spectrum analysis,and summarizes the nonlinear characteristics of the aerodynamic forces.The numerical simulation method effectively avoids the disadvantage of high cost and long cycle of wind tunnel test,and the numerical simulation results also have good reliability.The CFD numerical simulation method can be combined with wind tunnel test in the future study of bridge wind resistance,which can provide effective technical support for bridge design and construction.