Flutter Active Control Mechanism Of Streamlined Box Girder Based On Aerodynamic Panel Measure

With the improvement of modern construction technology and adoption of high-strength materials,bridge spans have increased significantly.However,the increase in the span has led to a decrease in the stiffness and frequencies of the bridge structures,and flutter instability has been one of the most important factors hindering further improvement of the bridge span.Active control aerodynamic panel is one of the most effective methods for suppressing flutter instability of a very long-span bridge.As a study model,we take a suspension bridge with a main span of 1160 m,which is simply supported at both ends.Aerodynamic panels are installed symmetrically to the left and right of the box girder.The influence of active control aerodynamic panel on the flutter performance is analyzed using a numerical CFD model,and the numerical model is verified by a wind tunnel test.The main work is as follows:1.The development of long-span bridges and classification of wind-induced vibration are reviewed,and the advantages and disadvantages of different flutter control methods are analyzed.It is considered that active control aerodynamic panel will be one of the most effective ways to improve the flutter performance in the future.Then the development process from passive control flaps to active control aerodynamic panel is reviewed.2.The theory of computational fluid dynamics and bridge flutter analysis is expounded.The complex eigenvalue method and step-by-step analysis method are used to solve the flutter critical wind speed by Matlab.By comparing the wind tunnel test results of the box girder section model,the step-by-step analysis method is determined as the flutter critical wind speed solution method.3.The bridge numerical model is built to obtained the basic structural parameters by ANSYS.In order to simulate the aerodynamic interference between the aerodynamic panel and box girder,aerodynamic panels are installed symmetrically to the left and right of the box girder.The width of the aerodynamic panel is 12% of the main girder.4.In order to accurately simulate the aerodynamic interference between the aerodynamic panel and box girder,a stable and reliable dynamic grid technology is introduced.Based on divided state forced vibration method,the user defined function(UDF)is applied to achieve the movement of the bare box girder and simplified model with aerodynamic panel.Finally,the flutter derivative and flutter critical wind speed of the box girder are calculated and analyzed.Comparison with the section wind tunnel test results,the numerical model is reliable.5.A numerical computational model is established.The influence mechanism of the aerodynamic panel on the flutter performance is analyzed,by studying the installation position of the active control aerodynamic panel.The influence of the aerodynamic panel on the airflow around girder is analyzed,by studying the spacing ratio between the aerodynamic panel and box girder.Through the study of installation ratio of the aerodynamic panel and phase difference between the aerodynamic panel and box girder,the optimal control method of the active control aerodynamic panel is analyzed.