Validation of fatigue design wind loads for natural wind gusts and for truck-induced wind gusts using full-scale measurements

Abstract

Full-scale instrumentation is carried out for a typical variable message sign overhead truss support structure and a typical simply supported tri-chord sign overhead truss support structure commonly found in Ontario, Canada. The measurements are used to develop wind loads and responses induced by natural wind gusts and by truck induced gusts. The results are used to investigate the modelling error, and to validate fatigue design wind loads in the context of the Canadian Highway Bridge Design Code. Comparison of the measured responses to the predicted responses obtained by using finite element (FE) models indicates that the actual responses of the instrumented structures are, on average, about 70% of that calculated by using the FE models, if the effects of aerodynamic admittance and spatially incoherent winds are not considered. The bias is practically eliminated if these effects are included. The modelling error is uncertain with a coefficient of variation of about 0.2. The statistics of the truck-induced wind pressure coefficient based on the full-scale measurements are consistent with those reported in the literature. They are used to support the calibrated fatigue design loads for natural wind gusts and for truck-induced wind gusts for Canadian practice.