Fatigue Evaluation of Orthotropic Deck for a Signature Bridge

Recently the fatigue performance of a replacement steel orthotropic deck for a signature suspension bridge was evaluated by full scale testing at the ATLSS Engineering Research Centre, Lehigh University. The deck consisted of closed trapezoidal ribs with full depth internal bulkhead plates and shallow subfloor beams with cutouts. Despite many benefits, in service fatigue cracking from bulkhead/subfloor beam-to-rib and rib-to-deck are of major concerns with orthotropic decks.

Fatigue testing was conducted using six actuators loaded in series, simulating the passage of tandem axles at three times AASHTO fatigue design load. A finite element analysis of the deck was performed to understand the deck complex behaviour of the and prediction of its fatigue performance. The study provided critical information on issues related to fabrication, installation, design improvement and the effectiveness of the replacement deck design in achieving more than 100 years’ service life.