Wind tunnel investigations of aerodynamic coefficients of road vehicles on bridge deck

To assess the safety of road vehicles running over a long span bridge in high wind, the knowledge of aerodynamic forces and moments on the vehicles is required. This could be obtained through wind tunnel investigations and expressed in terms of aerodynamic coefficients. However, very few investigations have been carried out to find aerodynamic coefficients of road vehicles on a bridge deck, compared with the aerodynamic coefficients of road vehicles on the ground. This paper therefore presents the results of wind tunnel tests carried out to determine aerodynamic coefficients of four types of road vehicles over a typical bridge deck. The aerodynamic coefficients of the same road vehicles on the ground are also presented to explore the effects of the bridge deck on aerodynamic coefficients. Different wind directions are taken into consideration to observe variations of aerodynamic coefficients with wind direction. Furthermore, the effects of vehicle position in different road lanes of the bridge deck are investigated. The test results show that the existence of bridge deck reduces side forces for all four types of vehicles remarkably but increases rolling moments to some extent. Such effects also vary with types of vehicles and lanes of the bridge deck where vehicles run.