Tuned Inertial Mass Electromagnetic Dampers For Bridge Cables:Theoretical Model And Vibration Control Performance

With the development of China's economic construction,the construction of cable-stayed bridges with kilometer-level span is increasing,so the length of the stay cables also reach 500 meters.The problem brought about by this is that the relative installation positions of various types of dampers are increasingly unguaranteed,and their damping performance also needs to be improved.Therefore,how to more effectively suppress the vibration of stay cables,especially the vibration of super long cables,to ensure the safety and economy of cable-stayed bridges in design and operation,has become a key issue to be solved urgently.In order to solve this problem,this thesis proposes a new inerter-based damper termed tuned inertial mass electromagnetic damper(TIMED),which has better damping properties and can provide considerable damping force in a smaller relative installation position.TIMED can achieve a large equivalent inertial mass,thereby significantly improving the damping efficiency of stay cable.In addition,it also has the function of energy harvesting,and is expected to realize the self-powered vibration control system,which has an attractive development prospect.In the thesis,according to the geometric structure of TIMED,the nonlinear mechanical model was proposed firstly.Then based on the principle of equal energy dissipation,the equivalent linearized mechanical model was derived.Furthermore,the frequency response function(FRF)of TIMED under harmonic load was obtained.Then based on the power flow analysis,its energy harvesting model was proposed.Finally,the accuracy of the above models was verified by the MTS dynamic test of the TIMED prototype.The study found that TIMED has adjustable frequency characteristics,adjustable electromagnetic damping characteristics and good energy harvesting performance.In this thesis,a 135-meter full-length cable was used to optimize the parameters of TIMED according to the eigenvalue analysis method.In addition,the dynamic response analysis of the stay cable-TIMED system under harmonic load and wind load was carried out.The performance comparisons between TIMED and uncontrolled,TIMED and viscous damper(VD),TIMED and tuned mass damper(TMD)were conducted.It had been found that TIMED has a significant advantage over other dampers for vibration control of a particular mode of cable.For cable vibration under wind load,the control performance of TIMED is also better than TMD and VD.