Driving Safety Of Vehicles On Bridges Considering Driving Behavior Under Cross Wind

In recent years,with the continuous increase of bridge span lead to the decrease of bridge body structural stiffness,the increase of bridge deck height make the wind speed increase,the complex environment of bridge site resulting in worse wind environment and many factors,the impact of cross wind on traffic safety on the bridge is becoming more and more important.Traffic safety accidents on bridges caused by cross wind are common,so it is of practical significance to study the safety and stability of vehicles in cross wind environment.Taking a high pier bridge in a mountainous area as the background,considering the influence of Reynolds number and test conditions,a 1:15vehicle beam and bridge model is designed and manufactured.Through systematic wind tunnel test,the aerodynamic coefficient of typical vehicles and its variation with bridge deck and incoming flow environmental parameters are studied;Through the self-made program,the operation law of vehicles on the bridge considering the influence of driving behavior under the action of cross wind is analyzed,and the influence of driving environment on driving safety index is studied,which provides theoretical and data support for the design value of critical wind speed for driving safety of vehicles on the bridge.The main work of this paper includes:(1)The aerodynamic coefficients of four kinds of vehicles in cross wind environment are explored,the variation laws of vehicle aerodynamic coefficients with different lanes and different ancillary facilities are compared and analyzed,and the influence of six component coefficient on driving safety and comfort of vehicles on the bridge is further studied.(2)Based on the aerodynamic coefficient obtained from wind tunnel test,the aerodynamic stability and evaluation index of high-speed vehicle are studied.The quasi-static coupling analysis model of vehicle and crosswind is established.Using the vehicle instability mechanics model,which mainly includes two failure modes of rollover and sideslip,the failure probability is quantified by introducing the reliability method,and suggestions are put forward for the setting of the critical wind speed of vehicle rollover and sideslip on the bridge.(3)Considering the complexity of the flow field in the process of overtaking in crosswind environment,especially when light and small vehicles(such as cars,small Van trucks,motorcycles,etc.)overtake large and heavy vehicles,the upstream vehicles have a strong interference with the flow field of downstream vehicles,forming a complex transient aerodynamic force acting on the vehicle and affecting the driving safety and comfort of the vehicle.Based on the quasi-static theory in the wind tunnel laboratory,the variation law of the flow field and aerodynamic force around buses and cars with the overtaking process is studied,and the effects of different wind deflection angles and the ventilation rate of auxiliary facilities on the driving safety of overtaking vehicles are explored.(4)Considering the control effect of driving behavior on the vehicle,the vehicle dynamic model of driving behavior is established to calculate the dynamic response of the vehicle on the bridge in the crosswind environment,and to predict more accurately the running state of the vehicle on the bridge under the crosswind.In addition,the dynamic response of the vehicle on the bridge without driving behavior is also compared,the importance of driving behavior for the safe driving of the vehicle in the crosswind is verified.The driving safety reliability analysis is further carried out,and the driving safety risk of vehicles on the bridge in cross wind environment is studied.