Steel Orthotropic Decks: Developments in the 1990s

Abstract

Recent developments in the field of steel orthotropic decks, which made possible the design of several recently completed highway bridges with record-breaking spans, are summarized. The more efficient, but fatigue sensitive, decks with closed ribs were prevalently used. Extensive research on the fatigue of closed-rib orthotropic decks was conducted, and the results were used in new deck design provisions in the United States and in Europe. Empirical design of details subject to distortion-induced fatigue has been adopted in the AASHTO Specifications. Recent fatigue cracks and failures in the deck plates of closed-rib orthotropic decks in the Netherlands brought to light the stress concentrations in the deck plate at rib intersections with the floor beams that were not previously recognized in the design. This observation is discussed, and a solution is proposed for future designs. Orthotropic decks with open ribs are free from second-order, local stress concentrations, and their fatigue performance has been generally satisfactory. Such decks have been extensively used on railway bridges in Europe. Also, several long-span highway bridges with open-rib decks have been built recently. Because of their good performance record, a more frequent use of the decks with open ribs on future bridges may be indicated. Surfacing research has shown that deck cracking is directly related to a composite action with the orthotropic deck, which must have adequate rigidity for good surfacing performance. Elastic properties of surfacings need more research. The possibilities for further development are included in the discussion.