Numerical Analyses On Coupled Vibration Response Between The Medium-low Speed Maglev Vehicle And T-shaped Rigid Frame Bridge

In recent years,medium-low speed maglev traffic has been valued and developed in China owing to its advantages of non-mechanical contact,low noise and green environmental protection.At present,four commercial lines have been put into operation or under construction.In order to span the existing highway and railway lines,Qingyuan maglev tourism line uses the large-span T-shaped rigid frame bridge with rotatable construction for the first time in the field of maglev transportation.To predict and evaluate the medium-low speed maglev vehicle running performance on T-shaped rigid frame bridge and the bridge dynamic performance,the coupling dynamic model of medium-low speed maglev vehicle-track-T-shaped rigid frame bridge is established in this thesis.Through the established vehicle-track-T-shaped rigid frame bridge coupling dynamic model,the effects of vehicle speed,load,marshalling,bridge temperature,shrinkage and creep on the coupling dynamic responses of vehicle bridge system are explored,which is expected to provide theoretical guidance and application reference for the engineering design of long-span T-shaped rigid frame bridge in the field of medium-low speed maglev transportation.Firstly,the dynamic model of maglev vehicle considering active control is established by UM and the finite element model of(2×60 m)T-shaped rigid frame bridge considering rail row structure is established by ANSYS.Base on the stablished model,numerical calculation of the coupling vibration responses between medium-low speed maglev vehicle and T-shaped rigid frame bridge realized in UM.In addition,the influence of concrete temperature,shrinkage and creep effect on T-shaped rigid frame bridge is calculated by Midas Civil,which lays a foundation for studying its influence on the dynamic responses between vehicle and bridge.Then,the dynamic responses of medium-low speed maglev train passing through the T-shaped rigid frame bridge at different speeds(20～160 km/h)in the case of 3-car and 6-car marshalling are simulated and calculated,respectively.The results show that the dynamic responses of maglev vehicle,maglev track and T-shaped rigid frame bridge increase with the increase of driving speed.The dynamic deflection span ratio is less than the limit of 1/4600,the bridge vibration acceleration is less than the limit of 5.0 m/s~2,the acceleration of vehicle body is less than 2.5 m/s~2 and the level of vehicle running stability is"excellent."Train marshalling has a great influence on the vertical displacement of T-shaped rigid frame bridge and rail row and the vertical acceleration of bridge,but has little impact on the dynamic responses of vehicle.After analyzing sections of bridge,it is obtained that 1/3 and 1/4 spans of bridge are the sections with largest deformation and acceleration amplitude respectively.Finally,the influences of vehicle load,bridge temperature load and shrinkage creep effect on vehicle and bridge coupling vibration responses are studied.The calculation results demonstrate that with the increase of load,the acceleration of vehicle decreases,and the vertical displacement and acceleration of track and bridge increase obviously.Compared with AW0 condition,the T-shaped rigid frame bridge vertical deformation and acceleration of AW3 condition increases by 66.5%and 12.4%separately.Considering the bridge temperature load and shrinkage creep effect,the vertical stability of maglev vehicle at high speed is reduced,which has weak effect on the dynamic response of suspension control system,track and bridge.Under the most unfavorable conditions,the maximum dynamic deflection span ratio of the bridge dangerous section is far less than the allowable value of1/4600.The maximum bridge vertical acceleration is 0.167 m/s~2,which is far less than the limit value of 5.0 m/s~2 in the specification.The vertical acceleration amplitude of vehicle is0.623 m/s~2,which is far less than the limit value of the maximum allowable vertical acceleration of 2.5 m/s~2.The vertical stability index reaches 2.42 and the level is"excellent".To sum up,under the most unfavorable conditions,the dynamic performance of vehicle and T-shaped rigid frame bridge meets the relevant technical specifications,which indicates that medium-low speed maglev train can be suspended stably and operates safely on the(2×60m)T-shaped rigid frame bridge.