Effect of sudden change of vehicle wind loads in windvehiclebridge system  by wind tunnel test

Abstract Under cross wind action, the wind loads acting on vehicle can be changed dramatically when vehicle is passing through the wake of bridge tower or two vehicles are passing each other, which will influence the running safety and comfort ability of vehicles. Based on the selfdeveloped of wind tunnel test rig with moving vehicle model, three-vehicle model and single-vehicle model are used to simulate respectively the rail vehicle and highway vehicle, the sudden change of vehicle aerodynamic forces are measured when vehicle is passing through the bridge tower and two vehicles are passing each other, and the effects of wind speed, vehicle speed, rail position of vehicle and vehicle type on the vehicle aerodynamic coefficients are investigated. The analysis show that the aerodynamic coefficients of vehicle have different degree of sudden change in the process of vehicle passing through the tower and two vehicles passing each other, the train induced wind can weaken the sudden change of vehicle drag coefficient, lengthen the effective region of windshield, the effect of sudden change of wind loads for the highway vehicle is more obvious than rail vehicle. The wind loads of vehicle which on leeward side of the deck rapidly decrease while the aerodynamic coefficients of vehicle which on windward side of the deck change smoothly during two vehicles passing each other.