Measurement-based traffic loading assessment of steel bridges - a basis for performance prediction

The Europabrucke, a well-known Austrian steel bridge near Innsbruck that was opened in 1963, is one of the main alpine north-south routes for urban and freight traffic. Currently the bridge is stressed by more than 30,000 motor vehicles per day (approximately 20% freight traffic). The superstructure is represented by a steel box girder (width 10 m, variable height along the bridge length 4.70-7.70 m) and an orthotropic deck and bottom plate. This motorway bridge with six spans of different lengths (longest span 198 m, supported by piers with an elevation of 190 m) and a total length of 657 m comprises six lanes, three for each direction distributed on a width of almost 25 m. It represents a bridge generation where bridge designers acted on a maximum of building material economisation. A long-term preoccupation of Vienna Consulting Engineers with the bridge monitoring system BRIMOS (R) on the Europabrucke (since 1997), with regard to fatigue problems and possible damage, led to the installation of a permanent monitoring system in 2003. As lifetime predictions in modern standards depend on lots of assumptions, the emphasis is to replace those premises (referring to loading) by measurements. A dynamic weight registration procedure for freight traffic (the major feature of the permanent monitoring system), mainly based on a pattern recognition algorithm, is introduced.