Numerical Simulation Of Bridge Flutter And Optimization Of Aerodynamic Measures Based On Two-way Fluid Structure Coupling

The long-span bridge with flexible system is very sensitive to the wind,and the wind-induced flutter has become an important problem to be considered in bridge design.With the development of computational fluid dynamics(CFD)theory and the rapid growth of computer computing speed,the numerical simulation method based on CFD has become an important means of bridge wind engineering research.In this paper,with the help of the second development of CFD general software FLUENT,the numerical simulation analysis of Bridge Flutter Based on two-way fluid structure coupling and the optimization of aerodynamic measures are realized.The main contents are as follows:(1)Research and verification of numerical simulation calculation method:combined with fluent dynamic grid technology,a hybrid grid generation method based on "rigid grid area+dynamic grid area+static grid area" is developed,which takes into account the calculation efficiency and accuracy;second development of FLUENT is carried out,Newmark-β method is used in structural calculation,and two-dimensional bridge is realized based on bidirectional fluid structure coupling Numerical simulation analysis of beam flutter.The UDF program is optimized from the bottom structure,so that the program can realize parallel operation.Combined with the previous grid division method,it provides technical support for the realization of the flutter numerical simulation analysis of the bridge with complex geometry section and multiple working conditions.Finally,the numerical simulation method is verified by comparing with the wind tunnel test results of a typical streamline section.(2)Calculation of critical flutter wind speed based on the real bridge:Based on the actual project,the above numerical method is used to simulate the flutter of the main girder sections of Taihong Yangtze River Bridge and miaozui Yangtze River Bridge with railings,maintenance tracks,guide plates and other ancillary facilities,and the critical flutter wind speed under different attack angles is obtained.The numerical simulation results are in good agreement with the wind tunnel test results,which shows that the numerical simulation method is still of high accuracy in identifying the critical flutter wind speed of the bridge girder section under the condition of complex geometry.(3)Aerodynamic optimization measures research and flutter mechanism analysis:according to the recommended scheme of the stiffening beam section of miaozui bridge,a simulation model is established to calculate the critical flutter wind speed,and the numerical calculation results are in good agreement with the wind tunnel test results.Finally,the detailed mechanism of aerodynamic optimization measures is analyzed,which provides theoretical guidance for the selection of similar bridge sections and flutter optimization measures.The numerical simulation method in this paper has good accuracy for the critical flutter wind calculation and flutter stability analysis of the bridge girder section under the construction state and the geometrically complex completion state.Compared with the wind tunnel test with long test period and high cost,it has high efficiency,low cost and good repeatability.However,the reliability of wind tunnel test is still irreplaceable,so the combination of numerical simulation method and wind tunnel test,the comparative analysis of the two,the flutter stability evaluation of long-span bridge girder section will be more efficient and accurate.