The Study On Vehicle-bridge Coupling Vibration And Fatigue Property Of Reinforce Steel Brace Composite Box Girder Of High-speed Railway

The main bridge of Weihe super-large bridge on Yinxi line of high-speed railway is a simply supported beam with a span of 60 m,and the section form is a composite box girder with stiffening steel diagonal bracing.This type of structure can effectively reduce the weight of the structure above the bearing,reduce the construction amount of the bridge substructure,and reduce the proportion of the cost of the bridge substructure in the total cost of the bridge.The design speed of this route is 250 km / h.When the train runs at a high speed,the bridge will have a relatively intense vibration effect,which also brings higher requirements for the fatigue resistance of the structure.However,as a new type of bridge structure,stiffened steel diagonal bracing composite box girder is first used in the field of high-speed railway in China.At present,the literature on vehicle-bridge coupling vibration research and fatigue performance analysis of this type of structure is very limited,so it is necessary to study the fatigue of this type of bridge.The research object of this paper is the stiffened steel diagonal composite box girder bridge of the main bridge of Weihe Bridge on the Yinxi Line.The vehicle-bridge coupled vibration model is established,and the vehicle-bridge coupled vibration analysis is carried out under different working conditions.The wheel-rail force history of the train is extracted and applied to the finite element model of the bridge to study the fatigue performance of the stiffened steel diagonal composite box girder bridge.This paper mainly has the following research contents :(1)The multi-body dynamics software SIMPACK and the general finite element software ABAQUS are used to establish the train dynamics model and the bridge finite element model respectively.The bridge structure is imported into SIMPACK as an elastic body to establish the vehicle-bridge coupling vibration analysis system.(2)SIMPACK and ABAQUS are combined for simulation.Six working conditions of single-line and double-line driving are selected for vehicle-bridge coupling vibration analysis.The calculation results are evaluated in combination with the vehicle-bridge dynamic evaluation standard to explore the variation law of vehicle-bridge dynamic response under single-line and double-line driving conditions at different speeds.(3)The nominal stress method and hot spot stress method in fatigue performance analysis method are introduced in detail.The fatigue performance evaluation steps of steel structures with complex structures are optimized.The refined bridge finite element model is established,and the train wheel-rail force history is extracted.With the help of VDLOAD subroutine in ABAQUS,the train wheel-rail force is applied to the bridge finite element model for transient dynamic analysis,and the fatigue stress history of vulnerable details is extracted.The rain flow counting method is used to process the fatigue stress history to obtain the stress spectrum.Combined with the S-N curve and the fatigue damage accumulation criterion,the fatigue damage assessment of steel inclined braces is carried out.