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Probabilistic traffic load model for short-span city bridges

L. Hellebrandt 1, C.B.M. Blom 2,3, R.D.J.M. Steenbergen 1,4

1 TNO, Structural Reliability, Delft, the Netherlands
2 TU Delft, Concrete Structures, Delft, the Netherlands
3 Ingenieursbureau Rotterdam, Rotterdam, the Netherlands
4 Ghent University, Department of Structural Engineering, Ghent, Belgium

In the coming years numerous existing traffic bridges in cities are subject to re-evaluation. In this paper a new probabilistic traffic load model for short-span bridges is proposed. As an example, site-specific weigh-in-motion data from Rotterdam, the Netherlands, is included in the model. The method proposed in this paper allows for a very efficient computation and at the same time takes into account the stochastics in axle loads and distances. For a simply supported 6 m single lane bridge the probabilistic load model provides a design load effect that is slightly lower than currently prescribed EN 1991-2 and the Dutch Guidelines for existing structures NEN 8700 and NEN 8701. This indicates that there is possible potential for a small reduction of the traffic load for short-span city bridges compared to the current standards. However, given the questionable quality of recorded measurements, a more extensive measurement campaign using WIM measurements is needed to get an adequate quantification of the traffic load parameters for city traffic conditions.

Key words: Traffic load, probabilistic, weigh-in-motion (WIM), short-span bridge