Fatigue Stress Amplitude Of Highway-Light Rail Steel Bridge In Service Analysis

With the development of urban rail transit,rail traffic bridge steel structure fatigue problem has attracted wide attention in the industry.The structural fatigue analysis is more complicated due to the diversity of the load.In this paper,the construction of the Chongqing Municipal Science and Technology Project " Study on Lateral Stiffness and Fatigue Design of Steel Box in Urban Rail Transit ",the highway-light rail steel bridge fatigue stress amplitude were analyzed.This paper first introduces the development trend of rail transit bridge,and expounds the basic theory of fatigue of highway steel bridge and the basic theory of fatigue analysis.It is concluded that the key to determining the fatigue stress amplitude of the bridge is to determine the fatigue load of the vehicle and find the internal force influence line of the checking component.The method of calculating the fatigue load model of highway and light-railway is obtained by summing up the fatigue model of the vehicle at home and abroad.Secondly,the traffic survey of Chongqing QianSiMen Bridge is carried out.The total weight of road fatigue vehicles is calculated according to the principle of fatigue damage equivalent.The road vehicle fatigue herein with other domestic bridge load spectrum for comparison,results in terms of area of Chongqing highway-light rail steel bridge upper road calculated fatigue stress amplitude fatigue load specification taken BS5400 standard fatigue vehicle is feasible.Calculate the equivalent axle load of the rail vehicle vehicle for each rail of Chongqing Rail Transit based on the traffic volume and vehicle parameters of Chongqing Rail Line 1,Line 2,Line 3 and Line 6.Steel highway-light Rail steel bridge or light Rail steel bridge design,the use of rail traffic prediction calculation standard rail fatigue axle weight,wheelbase vehicle design to take the actual wheelbase.In the absence of predictive traffic data can be taken directly axle weight 100 kN.While the fatigue analysis of the bridge in orbit of the in-service track or the rail will be determined by the actual weight of the rail vehicle and the actual traffic volume.Finally,based on the construction of Chongqing QianSiMen Bridge,the finite element analysis software Midas / civil 2015 was used to build the full bridge 3D model.Compared with the stress amplitude of the typical cross-section calculation point,it is concluded that the road load has a great influence on the structure of the main girder of the dual-use steel bridge,which has no effect on the structure of the lower beam.The stress amplitude result of the light rail model is opposite.Comparing the dynamic stress test results of the load test with the calculated stress amplitude,it is verified that the model of the road fatigue truck in the BS5400 standard is applicable to the calculation of the whole fatigue stress amplitude of the highway-light Rail steel bridge.Through the calculation to find the weak components of the bridge,and then in accordance with the norms at home and abroad on the door of the most dilapidated fatigue fatigue calculation,the results show that meet the regulatory requirements.It is shown that the standard fatigue vehicle model proposed in this paper and the highway standard fatigue truck in BS5400 can be used for the analysis of fatigue stress amplitude of highway-light rail steel bridge.