Displacement Response And Mitigation Of Large Span Suspension Bridge Subjected To Vehicle Excitation

The long-span suspension bridge has been widely built in China.However,the girder and the expansion joints are always subjected to serious damage.In fact,some expansion joints in long-span suspension bridge have been replaced.Overall,the expansion joints play an important role in the structural safety and service life of the long-span suspension bridge.Therefore,it is important to investigate the mitigation and mechanism of the longitudinal displacement response of the girder.(1)Firstly,a monitoring system is established in Aizhai Bridge to measure the longitudinal displacement and temperature of the girder.Overall,the measured data from March 1,2016 to November 3,2017 was obtained.Moreover,different method,i.e.,the statistics method,power spectral density function and wavelet analysis,were applied to deal with the measured displacement response.The results show that the longitudinal displacement response of the girder is affected by the vehicle load,ambient excitation and temperature.In fact,the vehicle load dominates longitudinal displacement response of the girder.(2)Then,the finite element model of Aizhai Suspension Bridge was built via the ANSYS software.The dynamic characteristics of the bridge were examined.Moreover,the finite element model was applied to investigate the longitudinal displacement response of the girder,and the parameter analysis was performed to study the effects of speed,frequency and roughness of pavement on the longitudinal displacement dynamic response.Based on the longitudinal displacement dynamic response of the girder,the damping parameters are optimized and the general optimization design ideas were summarized.(3)Finally,the Dongting Lake Bridge was chosen to investigate the effects of the central buckle on the longitudinal displacement dynamic response of the girder.To achieve this,three finite element model of the suspension bridge were built,and the effects of the stiffness of the central buckle on the dynamic characteristics of the bridge were examined.Moreover,the effects of the central buckle on the longitudinal displacement dynamic response of the girder were also investigated,and different conditions,i.e.,vehicle speed,vehicle driving direction,traffic flow and vehicle braking,were considered.The results show that the large stiffness of the central buckle can result in the small the peak value.However,the longitudinal displacement response of the girder exhibits larger cumulative displacement value.