Study On The Application Of Periodic Design In Vibration Control Of Key Components Of Bridges

Vibration,as a common problem in bridge service,seriously affects the health of bridges.Suppressing bridge vibration is helpful to ensure structural safety,extend the service life of the bridge,and reduce the maintenance cost of the bridge.Research on periodic structures(i.e.structures with periodic changes in geometric dimensions or material parameters)has found that they possess unique bandgap characteristics,which can play a role in vibration reduction and noise reduction in engineering applications,pointing out new research directions for bridge vibration control methods.The existing research on periodic structures is generally based on linear theory and infinite periodic structures,mainly focusing on the propagation characteristics of waves.However,in bridge vibration,the main focus is on the response amplitude of finite structure vibration,and the geometric nonlinear effect of cable vibration cannot be ignored.Based on the research background,this dissertation applies periodic design to key components of bridges,the beams and cables components in large-span bridges are periodically strengthened to form periodic beams and periodic cables whose elastic modulus and linear density change periodically along the length of the structure.The vibration control effect of periodic beams and periodic cables was studied from the vibration perspective.The main achievements of the dissertation are as follows:(1)Studied the vibration characteristics and vibration control effects of periodic beams.A calculation model for periodic beams was established,and a vibration analysis method for periodic beams was derived by combining equations of motion,state space theory,and joint coupling matrices method.The influence of periodic beam parameters on its natural vibration characteristics was analyzed,and the forced vibration response of periodic beams under harmonic and general dynamic loads was analyzed.A finite element model was established to simulate the periodic beam,verifying the vibration analysis method proposed in this dissertation and the vibration control effect of periodic beams.(2)The vibration control effect of periodic cables under distributed load was studied.A calculation model for periodic cables was established,and the equations of motion,state space theory,and joint coupling matrices method were combined to derive a periodic cable vibration analysis method under distributed loads.Then iterative solutions were performed based on its geometric nonlinearity characteristics.The vibration response of periodic cables under harmonic and general dynamic loads was calculated.(3)The vibration control effect of periodic cables under boundary displacement excitation was studied.On the basis of the nonlinear vibration analysis method in the previous section,the analysis model and vibration solution formula of periodic cables under lateral displacement excitation at the cable boundary have been modified.The vibration response of periodic cables under harmonic displacement excitation and general displacement excitation was calculated.