Fatigue Evaluation of a Steel Orthotropic Deck for a Lift Bridge by Laboratory Testing of a Full Scale Prototype

Recently, the design and fabrication of a proposed orthotropic deck for a vertical lift bridge were evaluated for infinite fatigue life by testing a full-size prototype of the part bridge deck at the ATLSS Engineering Research Center of Lehigh University. Contrary to the more conventional orthotropic decks, the design incorporated a thicker deck plate stiffened by round bottom ribs and fitted floor beams (FB). Although similar details have been implemented in service, infinite life fatigue performance of the deck for the proposed geometric parameters was not known. Multilevel 3D Finite Element Analyses (FEA) were performed to design the specimen and the test set up for adequately reproducing the design stresses due to AASHTO fatigue loading. The study provided critical information on issues related to cost-effective fabrication and rational fabrication tolerances, and established a life-cycle cost-effective standard orthotropic deck design that can provide a service life exceeding 100 years with minimum maintenance.