Investigation On Aerodynamic Measures For Coupled Flutter Of A Flat Steel Box Girder Based On System Energy Characteristics

A large number of wind tunnel tests and numerical simulations have been carried out on the mechanism research of bridge flutter and aerodynamic measures in the world at present,however,the selection and optimization of flutter aerodynamic measures in current wind tunnel tests are still blind.Based on the modal energy exchange in flutter micro-vibration process,the global energy input characteristics and the region energy input characteristics are given to investigate the effectiveness mechanism of aerodynamic measures for heave-torsion coupled flutter through experimental and numerical investigation.And the effectiveness numerical judgment of the aerodynamic measures was carried out in the CFD numerical wind tunnel to provide reference for subsequent wind tunnel tests and reduce the blindness of the tests.The following works have been conducted for this subject.(1)The wind tunnel tests of aerodynamic measures for heave-torsion coupled flutter were conducted firstly in present project.The general situation and content of wind tunnel tests were introduced.Then the vibration suppression effect of upper central stabilizer and cantilever horizontal splitting plate on the flutter was obtained by wind tunnel tests,including the relationship between amplitude and wind speed,static coefficients,the distributed pressure of model.Based on the above work,the influence of different aerodynamic measures on the model vibration situation,the overall aerodynamic force and the pressure distribution were investigated.(2)The energy input characteristics of different aerodynamic measures,including the global energy input characteristics and the region energy input characteristics were investigated based on the energy exchange characteristics in one micro-vibration period.The calculation method of energy input was given,and the result was analyzed.Then the vibration suppression mechanism of different aerodynamic measures was obtained.The results indicated that the global energy input characteristics could be used to determine the effectiveness of flutter aerodynamic measures and the region energy input properties could be used to find the "critical area" in vibration control,which provide the reference for the next optimization of aerodynamic measures.(3)The numerical effectiveness judgment of the aerodynamic measures for flutter was conducted by numerical simulation method.Firstly,the heave-torsion coupled vibration of flat steel box girder was realized in FLUENT software.Then the effectiveness investigation of the aerodynamic measures was conducted similarly based on the global energy input characteristics and the region energy input characteristics in one micro-vibration period.Lastly the numerical optimization of the height of upper central stabilizer for a bare beam of long-span suspension bridge was investigated based on the above-mentioned numerical method.The results demonstrated the numerical effectiveness judgment of the upper central stabilizer was practicable.The wind tunnel test could be carried out after the recommended measures obtained by the numerical study of the subject to reduce the blindness of test.