Using strain gauge measurements to predict load effects from traffic

Assessment of existing bridges in the Netherlands uses LM1 from the Eurocode NEN-EN 1991-2 and the additional national code NEN8700 series. The latter prescribes lower safety factors, based on a lower reliability index. Applying this load model for specific individual bridges may still be conservative compared to the actual traffic. There is a need for alternative methods to determine traffic load effects. This paper determines load effects from traffic by applying a probabilistic analysis on strain gauge measurements on key members of a large steel bridge. The process involves pre-processing the strain gauge data, fitting an extreme value distribution to the data and incorporating uncertainties and trends. The outcome of this study are design stresses of the measured load effects. The results are derived based on the codified reliability index and thus can be used during the assessment.