Effects of wind barrier on a vehicle passing in the wake of a bridge tower in cross wind and its response

Vehicles passing behind a bridge tower in strong cross winds are affected by sudden change of wind forces acting on them, which may cause accidents due to miss-steering of the drivers. As a countermeasure, wind barrier has sometimes been applied. However, the efficiencies of wind barrier are not known quantitatively, because the characteristics of the aerodynamic forces acting on a vehicle and the response of the vehicle due to those forces are not clear. In this paper, aerodynamic forces acting on a vehicle passing in the wake of a bridge tower with wind barrier are measured and their characteristics are presented first. Then, using the prediction procedures proposed in a previous study by the authors (J. Wind Eng. Ind. Aerodyn., submitted for publication), a vehicle response simulation was conducted and the effects of the wind barrier on the vehicle response were examined. In the experiment, the change of wind speed is confirmed to become moderate and the magnitude of the aerodynamic forces variation is found to reduce with the installation of wind barrier. Based on simulation results without wind barrier, the vehicle response becomes larger due to increased wind and vehicle speed, and reaches maximum when the wind direction is skewed 30degrees from the axis normal to the bridge axis and against the vehicle heading direction. The effects of the wind barrier were studied with a fixed steering simulation, and the responses such as side acceleration and yaw angular acceleration are found to be reduced effectively. (C) 2004 Elsevier Ltd. All rights reserved.