Study On Vertical Coupling Vibration Of Medium Speed Maglev Train Bridge System Of Steel-concrete Composite Continuous Beam

The steel-concrete composite girder bridge has attracted more and more attention because of its high stiffness,fast construction speed and good comprehensive benefits.The steelconcrete composite girder bridge has great development potential in the field of maglev transportation.The strong coupling vibration between the maglev train and the bridge will occur during the running process,and its strong coupling vibration effect will affect the operation safety of the maglev train.This paper focuses on the mechanism of vertical dynamic response of medium and low speed maglev train bridge system,and studies the influence of vehicle speed and load on the vertical coupling vibration of the system.Then,the influence of the key design parameters of the steel-concrete composite continuous beam on the vertical coupling vibration of the medium speed maglev train bridge system is studied,and the reference limit values of the key design parameters are put forward.The main work and conclusions of this paper are as follows:The theoretical models of subsystems such as maglev train,bridge and PID(proportional integral differential)active suspension control system are established respectively,so as to construct the vertical coupling vibration theoretical model of maglev train bridge system,and the solution method of coupling vibration system is briefly introduced.The secondary suspension has the function of vibration isolation,so that the vibration acceleration of the vehicle body is significantly less than that of the suspension frame,and the vehicle body shows low-frequency vibration to ensure the comfort of passengers.The PID active suspension control system can adjust the suspension force in real time according to the size of the suspension gap,so that the maglev train always fluctuates around the rated suspension gap,which ensures the smooth operation of the maglev train.With the increasing load of maglev train,the mid span vertical dynamic deflection and acceleration of steel-concrete composite continuous beam,the vertical acceleration of suspension frame,the fluctuation value of suspension gap and electromagnetic suspension force increase,while the vertical acceleration of vehicle body decreases.With the increasing running speed of maglev train,the mid span vertical dynamic deflection and acceleration of steel-concrete composite continuous beam,the vertical acceleration of vehicle body,the vertical acceleration of suspension frame,the fluctuation value of suspension gap and the fluctuation value of electromagnetic suspension force all show an increasing trend.When the maglev train runs on the 2×30.98 m steel-concrete composite continuous beam(beam height is 2.25m)at the running speed of 200km/h under the overload condition,the vertical dynamic responses of the bridge,vehicle body,suspension frame and suspension control system meet the specification requirements,and the surplus is large.The limit value of dynamic coefficient of the 2×30.96 m steel-concrete composite continuous beam is recommended to be 1.15,the limit value of vertical fundamental frequency is recommended to be 90/L,the limit value of vertical deflection span ratio is recommended to be increased to L/4000,and the allowable value of temperature variation is recommended to be relaxed to L/7000.