Inerter-based Dampers For Flutter Control Of Long-span Bridges

In order to improve the performance of traditional TMD-based flutter control,eight kinds of inerter-based dampers are proposed to control flutter of long-span bridges according to different combinations of spring-damper-inerter components.In this thesis,a suitable arrangement of inerter-based dampers for bridge flutter control is given,and the performance of TMD and eight inerter-based dampers is compared.Through comparative analysis,six kinds of inerter-based dampers with better flutter control performance are selected for parameter analysis,and the influence of each parameter setting on the flutter contro l effect of inerter-based dampers is discussed.The main research work and conclusions of this thesis are as follows:(1)The development history and the latest advances of bridge flutter control and inerter-based dampers are summarized.The two-dimensional and three-dimensional coupled flutter analysis methods in frequency domain and the mechanical impedance analysis theory are introduced,which lays a foundation for subsequent research and analysis.(2)Based on the two-mode coupled flutter theory and the motion differential equation analysis method,the differential equation of bridge-TMDI motion is established and the coefficient polynomial characteristic equation is derived.Taking the beam with ideal flat section as an example,the effectiveness of TMDI for flutter control of bridge is verified,and the influence of TMDI parameters on flutter control performance is investigated.The results show that the TMDI can effectively increase the critical flutter wind speed.Compared with TMD,the addition of the inerter will weaken its control effect,but it can greatly reduce the static displacement of the mass block,which is more practical in engineering.(3)Based on the two-mode coupled flutter theory and the mechanical impedance analysis method,the algebraic equations of motion of the bridge-MISD system are derived.Taking the beam with ideal flat section as an example,the flutter control performance of TMD TMDI and MISDs is studied in terms of flutter control efficiency and static displacement of mass block.The results show that MISD1,MISD4,MISD6,MISD3 and MISD2 are recommended for their high flutter control efficiency and structure simplicity,and MISD7 is recommended for its small static displacement of mass block.(4)Taking the Jiangyin Bridge as an examp le,the flutter control performance of the six kinds of inerter-based dampers mentioned above is analyzed,and the influence of MISD parameters on the flutter control is investigated.The results show that the effectiveness of inerter-based dampers for flutter control of bridge is very sensitive to its frequency,and increasing the mass and the distance betwen the damper and section center can effectively improve the performance of MISD based flutter control.Inerter will slightly weaken its flutter control effect.The influence of the damping ratio on the performance of MISD based flutter control depends on the mass of the MISD.The optimal spring stiffness ratio of the six kinds of inerter-based dampers is obvious,and the optimal value depends largely on the inerter and mass of the inerter-based damper.In this thesis,inerter-based dampers with better flutter control effect are proposed to control the flutter of long-span bridges,which provides a theoretical reference for the practical engineering application of the se inerter-based dampers.