Fatigue performance of laser-welded steel bridge decks

Steel orthotropic decks provide the most economical form of construction for long span bridges and other weight-critical structures. However, conventional stiffened plate decks are costly to produce and many have suffered premature deterioration or lacked wholly satisfactory longterm performance. This is largely because of fatigue susceptibility of fillet welds and also lack of endurance of roadway surfacing systems due to inherent flexibility of the lightly stiffened deck plate. Sandwich construction, with both lower and upper plates, would potentially be more efficient. In recent years laser welding technology has developed such that it is now feasible to fabricate sandwich panels from plates thick enough to be suitable for bridge decks.

Fatigue endurance is critical in the design of steel bridge decks. At the present time there is little data on the fatigue performance of laserwelded joints apart from butt welds. In this paper the fatigue performance of laser stake welds in two different configurations is examined with a view to assessing the overall fatigue endurance of sandwich panel decks. It is shown that the performance of laser-welded joints is very promising. Hence, the overall sandwich panel configuration is also likely to have good endurance and affords a radical evaluation of steel bridge deck design.

S. R. Bright, BEng, CEng, MICE

Cass Hayward and Partners, York House, Welsh Street, Chepstow, NP16 5YL

J. W. Smith, BSc (Hons), PhD, CEng, FIStructE, FICE
Department of Civil Engineering, University of Bristol, Bristol BS8 1TR