Experimental measurements of the loads induced on an overhead highway sign structure by vehicle-induced gusts

The results of an initial investigation of the induced horizontal loads by vehicle-induced gusts on an overhead highway sign structure are given here. The experimental effort was designed to measure unsteady loads on a model highway sign (1.30 scale) produced by a model vehicle passing underneath. Tests with varying vehicle speed, vehicle length, vehicle shape, and sign height were conducted. In all cases, the qualitative nature of the results were similar. Several characteristic features of these loads (which appear to be universal to all types of vehicles) have been identified and discussed in detail. Further research is needed were ambiguities exist. It was observed that the most severe wind-loading condition registered in the direction opposite to the vehicle motion and occurred when the leading edge of a rectangular vehicle was in the proximity of the sign panel. Typically, this force was approximately: the product of the dynamic pressure based upon the vehicle speed and the area of the sign. This load was followed by a force in the opposite direction of approximately 1/8 the same product which occurred later by Ut/L = 0.3. The latter force seems strongly dependent upon vehicle shape. (C) 2000 Elsevier Science Ltd. All rights reserved.