Mitigation And Response Of Longitudinal Movement Of Girders In Long-span Suspension Bridges

For the long-span suspension bridge,the longitudinal movement of the girder is closely related to the fatigue life of the expansion joint and the wear of the bearing.Whether the expansion joint and the bearing can work directly affects the service life of the suspension bridge,it also affects the comfort of the driving to a certain extent.Therefore,the research on the mitigation and response of the longitudinal movement has a very important engineering significance.In general,the main contents and conclusions of this paper are as follows:(1)Based on Aizhai bridge,the health monitoring system is established,and the data during the monitoring period is analyzed.The root mean square is used to analyze the relationship between the longitudinal movement and temperature.Then,the power spectral density function is used to analyze the frequency spectrum of the measured movement data.Finally,the influence of the longitudinal cumulative movement and the number of vibration of the girder on the expansion joint of the bridge is studied.(2)The structural modes of Aizhai bridge are simply identified by SSI method,and the natural frequencies and damping ratios of the first two modes are given.Then,the correlation between frequency and damping ratio and the RMS value of movement is analyzed.The results show that there is little difference between the results of the SSI method and the finite element method.(3)Based on the iterative method,a hybrid algorithm of vehicle bridge coupling vibration based on the central difference method is proposed,which regards the vehicle and bridge model as two separate subsystems.The central difference method is used to solve the motion equation of the vehicle system,and the newmark integral method is used to solve the motion equation of the bridge system.Then,the vibration response of vehicle bridge is solved.At last,two classical vehicle bridge coupling models are calculated and compared to verify the accuracy of the algorithm.(4)The finite element model of Aizhai bridge is established by ANSYS,and its dynamic characteristic is analyzed.Then,the longitudinal movement response of the girder is analyzed and compared.By analyzing the parameters of the damper and the central buckle separately,the influence of different parameters on the movement response is obtained.Moreover,the control effect of different vibration reduction measures on the longitudinal movement under different driving conditions are compared,and the optimal design idea of viscous damper and central buckle is proposed based on the analysis results.The results show that the central buckle can improve the longitudinal stiffness and effectively reduce the peak value of the longitudinal movement,but it has little influence on the cumulative movement.While the viscous damper is mainly sensitive to the short period component of the movement response and has little influence on the peak value of the longitudinal movement,but has obvious control effect on the cumulative movement.