Dynamic Response of Vehicle-Driver Couple to the Aerodynamic Loads due to the Crossing of a Bridge Tower Wake

In the paper, a procedure to assess the quality of the shielding effect of wind barriers to protect large sided vehicles crossing the wake of a bridge pylon under cross wind conditions is proposed. The methodology is based on Multi-Body simulations of the response of the vehicle-driver system when it is subjected to the sudden change of the aerodynamic forces due to the wind-tower interaction. The aerodynamic forces that are instantaneously acting on the vehicle are computed according to a force distribution approach that relies on wind tunnel tests that may be performed on still scaled models. From the knowledge of the aerodynamic force distribution along the vehicle at different yaw angles and of the mean wind profile across the tower wake, the aerodynamic force, acting on the moving vehicle, is reconstructed at each time step taking into consideration the actual vehicle-driver dynamics. The numerical procedure is applied to compare the different responses that the vehicle-driver system exhibits in presence or absence of wind barriers close to the tower. In particular the two situations are compared by computing the characteristic wind curves and considering synthetic indexes that are able to contemporary consider the risk of lane change or vehicle overturning, for different conditions of vehicle loading.