Vibration Response Analysis Of Track-Bridge Structure Caused By Operation Of Medium-Low Speed Maglev Train

The coupling dynamics of medium-low speed maglev vehicle-bridge is the research focus of maglev transportation,and also a key link in practical engineering technology.The vibration characteristics of the track-bridge structure are of great significance to the service performance,operational safety and service life of the structure.It is also of engineering value to deeply study the influence of the medium-low speed maglev vehicle-bridge coupling dynamics on the vibration characteristics of the track-bridge structure and the operation and maintenance of the structure.Based on the research background of medium-low speed maglev engineering lines,combined with the field test of track-bridge structure and the dynamic model of medium-low speed maglev vehicle-bridge coupling,the natural vibration characteristics of track-bridge structure are studied,and the vibration of maglev vehicle-bridge coupling dynamics performance is analyzed.Performance,and explored the dynamic characteristics of the track-bridge structure under train operation.The main research work of this article is as follows:(1)Experimental research on the vibration characteristics of medium-low speed magnetic levitation trackTaking the actual engineering route as the research background,modal hammering test and real vehicle test were carried out.The research shows that:the F-rail natural vibration frequency is distributed between 70Hz-120Hz under the tightened anchor bolt;the loosening of the anchor bolt makes the F-rail first-order vertical natural vibration frequency drop from 73.40Hz to 69.84Hz;the loosening of the anchor bolt causes the steel sleeper The first-order vertical natural vibration frequency is reduced from 79.44Hz to 64.33Hz;when the no-load train passes the track structure at 70km/h,the loosening of the anchor bolts increases the vertical acceleration of the F-rail from about 4m/s~2 to about5m/s~2.The loosening of the anchor bolts amplifies the vibration of the F-rail and increases the dynamic response of the track structure.(2)Analysis of vibration characteristics of track-bridge structureBased on the line engineering structure,the finite element analysis software was used to establish the track-bridge finite element model,and the vibration characteristics of the track-bridge structure were analyzed.When the anchor bolts are tightened,the first and second-order vertical natural frequencies of the bridge structure are 4.801Hz and17.878Hz respectively;the loosening of the anchor bolts reduces the first-order vertical natural frequencies of the track from 46.431Hz to 36.926Hz;the loosening of the anchor bolt reduces the sensitive frequency of the track from 45.82Hz to 36.28Hz;the response frequency is 41.41%lower than the inner side;the outer F-rail structure is more sensitive to low-frequency loads.(3)Medium-low speed maglev vehicle-bridge coupling dynamic modelCombined with the structural characteristics of the medium-low speed maglev vehicle bridge,the coupling dynamic model of the medium-low speed maglev vehicle-bridge is established based on the multi-body dynamics,structural dynamics and control theory.The Runge-Kutta method is used to solve the state space equation of the vehicle bridge.The electromagnetic force of a single electromagnet is simulated as the four most reflecting the electromagnetic force distribution of the vehicle,and with the reduction of the first-order natural frequency of the simple supported beam,the dynamic response of the simple supported beam and the suspension gap fluctuate more;compared with the light vehicle(23t),the dynamic response of the simple supported beam increases when the heavy vehicle(35t)passes through the simple supported beam;with the increase of the speed,the vibration response of the vehicle,the bridge and the control system increases.(4)Analysis of vibration characteristics of track-bridge during train operationCombined with the research of the coupling dynamic model of the medium-low speed maglev vehicle-bridge,the vibration characteristics of the track-bridge structure under the action of the train are analyzed.The results show that the vibration characteristics of the F-rail in the middle of the 12m span are better than that of the simple beam in the 24m span;with the decrease of the joint stiffness of the F-rail,the vibration displacement and acceleration at the joint increase;when the vehicle passes by,the vertical displacement of the outer F-rail is more average than that of the inner F-rail;with the transfer of vehicle load from top to bottom,the dynamic response of box girder is the smallest in the whole bridge system;with the decrease of anchor bolt stiffness,the F-rail vibration is obviously intensified,but the dynamic response of lower bearing beam and simply supported box girder changes little,and the track absorbs the impact energy of vehicle load.