Wind tunnel measurements of crosswind loads on high sided vehicles over long span bridges

Abstract

This paper presents the results obtained from a series of wind tunnel experiments undertaken in order to assess (and improve) the operation of a generic long span bridge subjected to strong winds (the operation of the bridge is evaluated in terms of the aerodynamic loads on a number of vehicles—in all cases the mean crosswind is greater than or equal to 10m/s). The aerodynamic loads, in terms of mean and peak side and lift force coefficients and rolling moment coefficient are presented for three 1:40 scale model vehicles placed on the bridge: a Van, a Bus and a Lorry. These vehicles were tested under static conditions (i.e., the motion between the vehicle and the bridge deck was not simulated), and subjected to a uniform turbulent crosswind at different incoming directions. Two separate bridge deck scenarios were examined—an ‘Ideal’ and a ‘Typical’ deck shape. The data show a good agreement with the findings of previous research with respect to the ‘Ideal’ bridge geometry. The Typical bridge section enables the differences between the idealised bridge and a more realistic deck geometry to be explored. The work indicates that the Lorry, rather than the Van or the Bus, is the critical vehicle in terms of overturning stability (as characterized by the highest magnitudes of the rolling moment coefficient). An approximately linear decrease of the side force and rolling moment coefficients is found on the Typical deck when the vehicle is positioned at a progressively larger distance from the windward edge. The research provides novel data and interpretation on the aerodynamic loads experienced by road vehicles.