Analysis Of Vehicle Safety And Reliability On Long-span Cable-stayed Bridge Exposed To Stochastic Winds

Bridge is the throat of transportation,and it is easy to be attacked by strong wind and generate strong vibration when crossing rivers and canyons.When the vehicle is driving on the bridge in a strong wind environment,the side force and lift of the vehicle increase sharply,and the possibility of side slip and roll accidents will also increase greatly.At present,wind load has become one of the key factors affecting the driving safety of long-span bridge.At the same time,the wind load has a certain randomness due to the existence of turbulence,and it has a greater impact on the safety and reliability of vehicles on the bridge.In this paper,the wind load is regarded as a random variable to analyze the driving safety and reliability of long-span cable-stayed bridge under cross wind.The main contents of this paper are as follows:(1)Using the Lagrange method,the vehicle models of four types of vehicles such as two-axis,three-axis,four-axis and five-axis are established;Based on the finite element model of the bridge,the modal motion equation of the bridge is established by introducing the modal superposition method;Based on the principle of virtual work,the coupling relationship between vehicle and bridge is established,and the aerodynamic load model of vehicle and bridge is introduced.Finally,the wind-vehicle-bridge coupling vibration analysis model is established,and the corresponding calculation program is compiled.(2)The aerodynamic characteristics of the wind vehicle bridge system of Dongpinghe super large bridge are studied by using CFD numerical simulation method;The vehicle aerodynamic coefficients and aerodynamic moment coefficients considering the aerodynamic interference between vehicles and bridges are obtained;the variation of vehicle aerodynamic load coefficients with the wind deflection angle is studied compared with the wind tunnel test results.(3)The static driving safety analysis method and the driving safety analysis method considering vehicle-bridge coupling vibration were established respectively,and corresponding calculation and analysis programs were compiled.The difference between the prediction results of the two methods was compared and studied.The result show that for side slip accident,the critical wind speed calculated by static driving safety analysis method is lower than that calculated by driving safety analysis method considering coupling vibration of vehicle and bridge;for rollover accident,it is just the opposite.(4)considering the randomness of wind speed,a limit state function model is established to solve the failure probability,and the response surface method is used to evaluate the reliability of vehicle driving safety on the bridge.The response surface method is used to calculate the failure probability of the side slip accident and the rollover accident of the vehicle under different speed and different wind speed,and to evaluate the safety of the vehicle on the bridge under the random wind load.