Reliability Analysis Of Curved Bridge Subjected To Heavy-haul Trains

The main heavy-haul railway lines are located in the mountainous areas of China's mid-west territory where many curves are set in order to suit the orographic condition.The curved bridge section is especially weak,and the dynamic responses of curved bridge are greatly influenced by the randomness of the ballasted track bridge system parameters.With the developing needs of transport speed,axle load and long grouping of the heavy haul railway,the reliability analysis of the curved bridge system subjected to heavy-haul trains considering the randomness of ballasted track bridge system parameters could provides a theoretical basis for both actual operation and future development of heavy-haul railway.The dynamic analysis model of curved bridge subjected to heavy-haul trains are established using SIMPACK software and ABAQUS software.The adequacy of the solving method which combine the vehicle model and the spatial finite element model of ballasted track bridge is being confirmed experimentally by in situ measurements.The acceleration response value of the bridge deck is used as the control index for the safety operation of the bridge and the superstructure.The 2k factorial design is applied to select the sensitive parameters of the ballasted track bridge system.On the basis of parameter sensitivity,the response surface method and the first-order second-moment method are used to solve the reliability index of the ballasted track bridge system under different conditions.The main conclusions are as follows:1)Compared to one factor at a time method,2k factorial design method could pay attention to the interaction effects,the results demonstrates that the interaction effects can be more important than single effects.Sensitive parameters of bridge dynamic response are mainly form itself.2)The ballasted track bridge system are safe under two kinds of track irregularity when the vehicle axle load is 30 tons.The failure probability of ballasted track bridge system in lateral and vertical directions are greater when the radius of curved bridge decrease.3)The failure probability of the ballasted track bridge system is greatly improved compared with the 800m curved beidge under two kinds of track irregularities when the radius is less than 800m.For example,the ratio of the lateral and vertical failure probability of R600m compared to the R800m under the measured track irregularity are ? and 2.70×1042.Considering the service performance of the ballasted track bridge system under heavy load,the curve radius of R800m and above is recommended in the new heavy-haul railway route design.4)Track irregularity has a great influence on the failure probability of curved ballasted track bridge system.The system failure probability under the sixth grade track irregularity of U.S.are far greater than the measured track irregularity conditions.For example,the ratio of the lateral and vertical failure probability under the the sixth grade track irregularity of U.S.compared to the measured track irregularity when the radius is 800m are ? and 1.07×1031.It's shows that strengthening maintenance of the track structure could significantly improve the reliability of ballasted track bridge system subjected to heavy-haul trains.5)The failure probability of track bridge system in lateral and vertical directions are greater when the axle load of the vehicle increase.In order to ensure the safety of the existing heavy haul railway bridge under larger axle load vehicles,the vehicle axle load should be controlled below 35 tons.