Reliability evaluation of the Eurocode model for fatigue assessment of steel bridges

In European countries, the design of bridges is conducted following the specifications in the Eurocodes. For verification against fatigue of steel bridges, a simplified model is suggested based on a single vehicle load model together with λ factors to estimate a representative stress range. Since the release of the Eurocodes the accuracy of this format has been discussed and questioned. In the current paper, a probabilistic model for fatigue assessment is suggested estimating the load effect from bridge weigh-in-motion (BWIM) measurements. The probabilistic model has been used to estimate the reliability reached with the existing verification format for road bridges. The result shows a large scatter depending foremost on the bridge geometry and the traffic volume. A tentative calibration of the verification format has been performed and new functions for two of the λ factors have been derived. With these new functions a significant improvement in the consistency of the reliability level has been achieved. The study demonstrates the need for a more extensive calibration of the Eurocode model and indicates the parameters to focus on.