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Eurocode 3 Part 2 - Steel bridges - design of orthotropic steel decks

Koistein, M.H. / Bruls, A.

Higher wheel loads and increasing traffic intensity mean that bridges are subjected to greater fatigue loading than in the past. This has resulted in the occurrence of fatigue cracks in modern steel bridges within their service lives. Also, detailing and fabrication was not always carried out to a sufficient high standard. Detailed studies of the fatigue design and behaviour of steel bridges were required in particular on the components of orthotropic deck structures, as the deck is directly subjected to the severe impact of heavy wheel loads. The works of this research on the fatigue design of orthotropic steel decks take place in a European inter-laboratory study. The aim is to derive conclusions and recommendations on how to produce more efficiently designed steel orthotropic bridge decks against fatigue, and how to further develop existing codes accordingly to promote the use of steel in bridge construction. The research program includes the fatigue assessment of a heavy loaded orthotropic steel bridge deck using measured stress spectra and fatigue strength curves of specific welded details intended to be included in Eurocode 3, part 2, Steel bridges and plated structures. Furthermore, calculations have been made of a similar deck using influence lines for some of these details using the fatigue design loadings of Eurocode 1, part 3, Traffic loads on bridges. Results show that compared to fatigue calculations using measured stress spectra, the fatigue load models of the Eurocode lead to a more conservative design which results in heavier steel decks. Furthermore, the influence of the temperature on the composite action of the deck surfacing and steel deck must be included in the design rules. Without this effect the calculated design life of the orthotropic decks would be considerably underestimated.