Research On New Type Of Vibration Reduction Method For Stay Cable

Cable-stayed bridge is popular among the bridge engineering field as its' economy,beautiful appearance,strong spanning capacity etc and it is one of the preferred bridge of large span bridge.With the development of transportation,more and more large span cable stayed bridges have been built.The span of cable stayed bridge is increasing,and the length of stay cable is longer.The cable which has the characteristic of light weight,small damping and bending stiffness makes it easy to produce different forms of vibration under wind load,rain load,vehicle load,And the vibration is more likely to be occurred with increasing of the length of the cable.The long time vibration of the cable is easy to induce undue fatigue inc-ables themselves and in anchorages at bridge deck and tower,even causing the phenomenon of broken cable.Therefore,the vibration control of cables is one of the first problems to be solved in the construction of long-span cable-stayed bridges.At present,the main methods for vibration control of cables include: adding suitable dampers in the structure,using the design method of aerodynamic to change the surface of the cable form,adding auxiliary cables in the structure and so on.Although these methods can reduce the vibration of cables to a certain extent,there are still many limitations.In order to seek new methods for the vibration reduction of the cable,this paper has carried out experimental research on 4 kinds of cable vibration reduction methods,and the research contents and results are as follows:1)A simple TMD device with adjustable parameters is designed.The mechanical properties of the TMD device are understood by the monomer test,and the design of the model is proved to be reasonable and effective.Experimental model of cable-TMD system is designed,and the finite element model of cable-TMD is establish.Both experimental and the finite element results show that the TMD has a good effect on vibration damping,and the TMD used for cable vibration is feasible in actual engineering.2)Both the results of the study and engineering practice show that the effect of the viscous damper is weakened when the coupling vibration with cable and girder.In order to ensure the good vibration damping effect of viscous damper under the coupling vibration with cable and girder,the vibration control methods of the viscous damper with MTMD are proposed in this paper.Therefore,a simplified theoretical modal with cable,viscous damper and TMD is analyzed by complex modal method,and experimental model of cable-damper-TMD system is designed.Both theoretical and experimental results showsthat the TMD can improve the vibration damping effect of viscous damper,when the frequency of TMD is near to frequency of cable;the viscous damper with MTMD is effective to suppress cable vibration,especially for the coupling vibration with cable and girder.3)The method of suppressing the vibration of the cable by using the damper is put forward.Experimental model of cable-damper system is designed,and its dynamic simulation has been implemented with the SIMULINK.The results also show that the dampers are effective in restraining the cable vibration,and it is feasible to suppress the vibration of the long cable by using the damper.4)The method of suppressing the vibration of the cable by using the TLD is put forward.First,experimental model of TLD is designed,and the TLD monomer test is carried out.Then the experimental research on the cable-TLD composite system is carried out.The study shows that it is feasible to use TLD to suppress the cable vibration.The research results provide a new method for the simultaneous control of the inside and outside complex coupling vibration of stay cable.