Wind-induced Vibration Control Of Long-span Bridges Based On Vortex Generators

With the increasing of the bridges span,the structures are becoming more and more flexible,and the structures are sensitivity to wind load,and the bridge system is more vulnerable under wind-induced vibration.To control the wind-induced vibration of the long-span bridges,this thesis adopts the study on the control technology of wind-induced vibration of the bridges in use of the active and passive vortex generator.The control effects are compared by cylindrical model static tests,PIV flow field display,vortex-induced vibration tests of the cylinder model,vortex vibration section model test and bridge flutter test research.In this thesis,the boundary layer suction control is simulated as a kind of active vortex generator control.The characteristics of the two kinds of vortex generator control effects were studied.The main contents in this thesis are summarized as following:1.Based on suspension bridges and cable-stayed bridges,the brief histories and researching achievements of long-span bridges are reviewed.And four types of the long-span bridge wind-induced vibration are described,such as flutter,vortex-indued vibration,buffeting and galloping.And the theories of boundary layer are introduced briefly,the development of the theory of flow control is reviewed,and the flow control methods are analyzed and evaluated.On this basis,the emphasis on the vortex generator in the aviation industry is introduced.2.To analysis the influence of the vortex generator on flow field,the fixed cylinder with the vortex generators pressure experiment is carried out.By analyzing the distribution of surface pressure and the velocity distribution of cylinder wake,the influence of the vortex generator on the flow field around the stationary cylinder is illustrated.3.For a more detailed study on the influence of the flow field around the cylinder with the vortex generators,according to the characteristics of vortex generators and the wind tunnel laboratory,A vortex generator measure ment test system was built and PIV technology is used in the wind tunnel test,the control effect of the vortex generator was verified by analyzing the cylinder wake flow field.4.To study vortex generator technology to control vortex-induced vibration,based on the static test,free cylindrical vibration test system was set up in the wind tunnel experiment.By contrast of displacement amplitude,cylindrical surface wind pressure distribution and the correlation between different sections,the vortex genertor control effect is verified on the vortex-induced vibration.5.To study the control effect of vortex generator on the bridge main girder vortex-induced vibration.Taking Great Belt East Bridge section model as the research subject,wind tunnel test method was carried out to study the suppression effect vortex-induced vibration of the active vortex generator for large-span bridge girder.Comparative study of different suction arrangement,active vortex generator under different suction flow rate of the bridge girder vortex-induced vibration control effect.The suction effects on aerodynamic stability of the bridge were studied by numerical method.6.The Great Belt East Bridge is also selected as the prototype t o study the control effect of the vortex generators on the long-span bridge flutter.In the process of flutter critical state analysis,the MITD method is used to identify flutter derivatives.The mixture firefly algorithm,combination genetic algorithm and quantum genetic algorithm is put forward on the basis of traditional firefly algorithm to gain flutter critical velocity and critical frequency.