| With the gradual improvement of the domestic railway network,the continuous improvement of train operation speed and the rapid increase of traffic volume,the novel double-layer and multi-line railway steel bridge began to appear in the construction of railway bridges.The interaction between the train and the bridge is more complex when multi trains are running on the double-layer and multi-line bridge,so it is necessary to study the coupled vibration of the train bridge system when the double-layer and multi-line train is running at the same time.With the continuous occurrence of some fatigue failures in the connection details of existing steel bridges,the fatigue problem has also become one of the key indicators of steel bridges.The increase of train speed and axle load not only makes the coupling vibration of train and bridge more significant,but also aggravates the fatigue load effect of bridge.Therefore,it is necessary to study the fatigue of steel bridge based on train bridge coupling vibration analysis.In this paper,the train bridge coupling vibration analysis is connected with the fatigue analysis of the railway steel bridge,and the double-layer and multi-line train bridge coupling vibration analysis is carried out for the selected double-layer and multi-line railway cable-stayed bridge.At the same time,based on the train bridge coupling vibration results,the fatigue research is carried out for the connection details of the main truss members of the bridge.Based on the coupling vibration analysis theory of vehicle bridge system,a super large railway cable-stayed bridge with double layers and six lines is taken as the research object in this study.The coupling vibration simulation model of train bridge system is established to analyze the coupling vibration of vehicle bridge.At the same time,based on the results of train bridge coupling vibration analysis,the fatigue of the bridge is studied.The main research contents are as follows:(1)Based on the basic theory and modeling method of multi-body dynamics,the finite element model of the whole bridge and the train dynamics model are respectively established by using the finite element software ANSYS and the multi-body dynamics software SIMPACK.Based on the realization method of introducing the elastic body substructure into SIMPACK,the coupling vibration simulation model of the train bridge system is established by using the wheel rail contact system.(2)In the train bridge coupling vibration system,considering the different track irregularity of the upper and lower layers,the vehicle bridge coupling vibration calculation is carried out under 10 working conditions,including single track driving,double track driving on the same layer,double track driving on the double layer and three track driving on the double layer.According to the evaluation criteria,the vehicle bridge coupling vibration dynamic index is evaluated when driving on different lines;the double track,double track and three track driving on the double layer are compared with the dynamic indexes of vehicle bridge under corresponding single line driving.This paper analyzes the influence of different loading methods on the dynamic indexes of double-deck and multi-line bridge.(3)Based on the results of train bridge coupling vibration analysis,three working conditions are selected,and the wheel rail force of the train is loaded on the bridge model in ANSYS in the form of moving concentrated load.The transient analysis is carried out and the stress time history of various members of the main truss is obtained.The rain flow method is used to treat it as stress amplitude,and the stress time history and the change of stress amplitude of fatigue members under each working condition are summarized and compared.Based on the S-N curve,the fatigue assessment is carried out,and the maximum damage degree of the connection details of the most unfavorable fatigue members in the design and operation life of the bridge is calculated by Miner linear damage theory and S-N curve. |
PDF Full Text Request