Influence Of New Type On-bridge Elastic Short Sleeper Vibration-damping Track On Vehicle-bridge System

The vibration-damping track used on the urban rail transit viaduct should not only consider the vibration-damping effect,but also minimize the impact of the track's own weight on the bridge.In the traditional sleeper wrap-type vibration-damping track,the sleepers are built in a way of being buried in the track bed,which has the disadvantage that the self-weight is large and the water cannot be discharged which entered the waterelastic wrap.In this paper,we studied a new type of elastic short sleeper-type vibration-damping track's usibility on the urban rail transit viaduct with a vibration-damping grade reaching a high level of vibration-damping.Through the finite element analysis software Abaqus,the modal analysis of the new elastic short sleeper-type vibration-damping track and the existing elastic short sleeper-type vibration-damping track was carried out.Due to the advantages of the new elastic short sleeper-type vibration-damping track with light weight,the new elastic short sleeper-type vibration-damping track has less influence on the natural frequency of the simply supported box girder bridge than the existing.The static analysis of the single new elastic short sleeper and the existing elastic short sleeper is carried out.The calculation shows that the gap reserved between the bottom of the new elastic short sleeper and the groove of the track bed makes the side support elastic pad easier to shear.The shear deformation can bear the load more effectively,and the maximum equivalent stress on the new elastic short sleeper is significantly reduced.Combined with the finite element analysis software Ansys and the multi-body dynamics software UM,the vehicle-track-bridge dynamic interaction model was established based on the new elastic short sleeper-type vibration-damping track structure and the typical vibration-damping track structure existing that used on the viaduct.The vehicle parameters are selected according to urban rail transit type A vehicles,and the bridge is built according to the 32 m double-line simple supported box girder bridge.The effects of vehicle speed,fastener stiffness and elastic sleeper support stiffness on the dynamic characteristics of the new elastic short sleeper-type vibration-damping track structure are considered respectively.The research results show that for the new elastic short sleeper-type vibration-damping track,as the train speed increases,the stability of the train operation,the stability of the track structure and the vibration-damping effect will decrease.The support stiffness of the elastic sleepers is in the range of 10kN/mm~25kN/mm,and the change of stiffness has little effect on the safety and stability of vehicle operation and the vibration reduction effect of the bridge.The dynamic characteristics of the new elastic short sleeper-type vibration-damping track and the typical vibration-damping track are compared in the time and frequency domainsrespectively.From the time domain,when the speed is 100km/h,the vibration-damping effect from high to low is steel spring floating slab track,new elastic short sleeper type vibration-damping track,vibration-damper fastener track and ordinary integral track bed track.With the improvement of the vibration reduction effect,when the vibration transmitted to the external environment is reducedthe,the vibration of the train is aggravated and the stability of the train operation is reduced.The track structure of the new type of elastic short sleeper type vibration-damping track has the best stability.For better comparison,when keep the stiffness under the rail of the new elastic short sleeper-type vibration-damping track same as the stiffness of steel spring floating slab track,due to the vibration of the elastic short sleeper less than the floating plate,the vibration transmitted caused by the new elastic short sleeper-type vibration-damping track to the bridge is greater than the the steel spring floatingslab track.In the frequency domain,compared with the ordinary integral track bed track and the vibration-damping fastener track,becaus of the effect of short sleepers and floating slabs the energy of rails and bridges in the low frequency band was reduced in the new elastic short sleeper-type vibration-damping track and the the steel spring floating slab track.In the middle and high frequency bands,the energy value of the rail in the new elastic short sleeper-type vibration damping track is smaller than that of the steel spring floating slab track.It can be seen that the new elastic short sleeper-type vibration-damping track can play a good role in suppressing the vibration of the track at low and midle-high frequencies.