Theoretical Analysis And Simulation Study On Vibration Of Stay Cable By Inertial Mass Dampers

With the continuous innovation and progress of cable-stayed bridge construction technology,large-span cable-stayed bridges continue to emerge.Therefore,effectively controlling the vibration of cable stayed is the key to achieving safe operation of cable stayed bridges.The installation of an external passive damper device near the end of the stay cable has become the main vibration damping measure for current stay cables.It has been successfully applied and achieved better vibration reduction effect.In view of this,this paper proposes a passively controlled inertial mass damper,which provides a larger inertial force to the damper by generating an amplified equivalent mass,which in turn provides greater damping to the cable and dissipates more energy To effectively control the vibration of the cable.The specific research work and results obtained in this paper are as follows:(1)In this paper,the development process of cable-stayed bridge’s continuous span refreshing and the damage caused by large-scale vibration of cable-stayed bridge are described.The research status of vibration types and control measures of cablestayed bridge are summarized.The bridges with dampers installed at home and abroad are extensively investigated and classified.The development process and research status of inertial dampers are summarized.(2)Starting from the working mechanism of the ball screw,the mechanical characteristics and damping force expressions of the inertial damper are introduced systematically;the negative stiffness effect of the inertial damper and its energy dissipation efficiency enhancement mechanism are analyzed;the cable-damper is established The mathematical model of the system is analyzed and the dynamic characteristics are analyzed.The influence of the dimensionless inertial mass and damping coefficient of the inertial damper on the modal damping ratio of the system is analyzed.The results show that the mass elements of the inertial damper can produce a large inertial mass,the negative stiffness effect is conducive to improving the damping effect of the stay cable,the damping element can increase the energy consumption of the damper,and the small changes in the inertial mass and the damping coefficient.With the increase of the cable mode,the maximum modal damping ratio of the system does not change much,but the corresponding two optimal parameter values decrease;the maximum damping ratio of the first third-order mode of the inertial damper is about ordinary viscous damping 9 times of the damper,indicating that the inertial damper can play a better role in reducing vibration and energy consumption in cable vibration.(3)Based on the horizontal tension string theory,the cable-damper system models of SVMD,PVMD,TID,and TVMD are established respectively;the dimensionless inertial mass,damping coefficient,stiffness coefficient,and damper installation position are analyzed to the front The effect of the first-order modal damping ratio;the negative stiffness effect of four inertial dampers is studied;The results show that there is an optimal parameter for each order modal change of the four inertial dampers,but under the same parameters,the vibration damping effect of PVMD is better than that of SVMD.Under the same conditions,the energy dissipation of TID is better than TVMD..For the first-order vibration of the cable,the three-element inertial mass damper(TID,TVMD)has a better damping effect than the two-element inertial mass damper(SVMD,PVMD).(4)The finite element simulation model was established by ANSYS,and the first10 order modal dynamic characteristics of the cable were analyzed.The dynamic characteristics of PVMD,TID,and TVMD installed at the cable beam end,tower end,and cable space were studied.The first 10 th order modal damping ratio and its change law;the results show that: installing an inertial damper near the main beam of the cable increases the damping ratio of the low order modal system;the cable is installed near the beam end and the bridge tower Inertia-type dampers,the system’s first 6-order modal damping ratio is about twice that when the damper is installed only at the beam end,and among the three inertial dampers,the overall TID of the first 10-order modal of the cable The vibration damping effect is relatively good;when the cable is installed with a damper in the space position,it is beneficial to the cable vibration control of the low-order mode,and the modal damping ratio of the even-order vibration of the highorder mode is increased but decreased;For the first-order modal vibration control,the TID-cable system has the best vibration damping effect when it is close to the beam end and the space 3L/4 position.(5)In view of the defects of the installation height of super long stay cable and the control effect of single damper,the motion equation of VD,VMD,TID and TVMD combined cable double damper system is derived and solved numerically.The space state equation obtained from the solution provides reference value for the dynamic characteristic analysis and damper parameter optimization of cable combined damper system.