| The rapid rise of high-speed railway has promoted the development of our country’s economy.With the increase of train speed and load,and the extensive use of bridge structures in railway lines,the study of vehicle-bridge coupled vibration is becoming more and more important.Long-span cable-stayed Bridges are widely used due to their advantages of strong spanning capacity,good wind resistance and large overall stiffness.It is of great theoretical and practical significance to study the dynamic performance of long-span Bridges under the action of moving vehicles and the operation safety and stationarity of vehicles on the Bridges.This paper is based on the construction of the long span steel truss cable-stayed bridge in mingyuexia.Based on the theory of multi-body dynamics and finite element,the total equation of vibration of vehicle-bridge coupling system is derived.Using the multi-body dynamics software UM,the 3d fine simulation model of CRH type bullet train and trailer was established.The full bridge model of mingyuexia Yangtze River Bridge was established by ANSYS and MIDAS CIVIL,respectively,and the natural vibration characteristics of the two were analyzed.The results of the two analyses were compared,and the reliability of the bridge model was verified by combining with the vibration characteristics of long-span cable-stayed bridge.According to the relevant domestic and foreign specifications,the evaluation standard of vehicle and bridge system vibration performance suitable for the bridge studied in this paper is determined.Taking the singletower railway cable-stayed bridge as an example,the vehicle-bridge coupling simulation analysis is carried out to verify the accuracy and efficiency of the modal synthesis method.The vehicle-bridge coupling joint simulation analysis of mingyuexia Yangtze river bridge was carried out by the combination of multi-body dynamics software UM and ANSYS.Based on the research of single-lane crossing bridge,the influence of vehicle parameters(running speed,wheel tread,truck marshalling,number of vehicles),internal excitation source(different track spectrum),bridge structural parameters(damping ratio,the second phase constant load)on vehicle-bridge system is explored.The conclusions of the corresponding regularity are obtained,which provide some references for the speed control,marshalling,acceleration,design calculation and construction of bridges.The analysis results are as follows:(1)The dynamic response results of vehicles and Bridges generally increase with the increase of driving speed.The driving speed is a main factor that affects the vibration of vehicle bridge system.Taking the mingyuexia bridge as an example,some suggestions are put forward for the high-speed train to speed up and run through the mingyuexia Yangtze River Bridge in the later stage.From the perspective of safety,it is safe for the train to speed up below 300km/h to pass through the bridge,but it does not have the conditions to speed up to 300km/h to pass through the bridge.If the speed is increased to300km/h above the Bridge,the line must be modified before it can be used.(2)Different wheel tasters have little impact on the vibration response of the bridge.The lateral stationarity of LMA tasters is obviously better than that of LM tasters,which can effectively improve the dynamic performance of the vehicle and bridge system.(3)Axle load is one of the main factors affecting the bridge vibration and the lateral force of wheel and rail.The driving safety and stability of full load truck is better than that of no load truck.Mixed trucks and fully unloaded trucks are unfavorable forms of marshalling,and unloaded trucks are more prone to derailment than full trucks,especially empty trucks in mixed trucks.Taking the mingyuexia bridge as an example,when the mixed truck and the fully assembled empty vehicle cross the bridge at the speed of 120 km per hour,the two types of empty vehicles will have a greater risk of derailment.Corresponding control measures should be taken for these two types of truck marshalling to pass the bridge.Proper deceleration should be carried out before entering the bridge to avoid entering the bridge at the speed of 120km/h.It is recommended that the speed should be uniformly controlled within 100km/h before entering the bridge.(4)To some extent,the increase in the number of vehicles has a small impact on the vibration response of vehicles and Bridges,but the increase in the number of vehicles will increase the duration of the maximum vibration of the main span,which has a certain impact on the fatigue durability of bridge structures under long-term action.(5)Track irregularity is a major factor affecting the vehicle-bridge system.The worse the track condition is,the greater the dynamic response result of vehicles will be,and the more violent the vibration response of bridges will be.In the process of highspeed railway construction,it is very necessary to strictly control the construction error of track.(6)The vehicle vibration response is not sensitive to the change of the bridge damping ratio and the second phase constant load.With the increase of the second phase constant load,the maximum vibration displacement of the main span of the bridge increases and the maximum vibration acceleration decreases,but the rate of change of the acceleration is obviously higher than that of the vibration displacement.The dynamic performance of axle system can be effectively improved by the proper second phase constant load. |
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