Fatigue Durability of Concrete Bridge Decks

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Victor Li, University of MichiganThe investigation addresses the fatigue durability of concrete bridge decks. Recent research suggests that the fatigue cracking can be a precursor to severe failure of concrete bridge docks. The fundmentals of fatigue damage and corresponding remedial action on bridge decks are currently poorly understood. This investigation focuses on basic understanding of fatigue durability of concrete bridge decks and on fatigue durability enhancement by the use of fiber reinforcement. fiber reinforcement is especially focused on because of the extensive documentation of fatigue resistance enhancement of fiber reinforced concrete (FRC) in laboratory. The mechanism of crack growth under fatigue loading, and aggregated and fiber bridging (across a concrete crack) response subjected to cyclic loading, are analyzed with a statistical/micromechanics based theoretical model. In addition, the degradation of the fiber/cement and aggregate/cement interface are expilicitly accounted for based on experimental observations.Four important consequences of this research are:1) Bridge deck slab design procedure against fatigue damage; 2) Fundamental understanding of the mechanisms governing fatigue failure of FRC; 3) Micromechanics based model for design of fatigue resistance FRC composites; and 4) Evaluation/repair procedure of brige decks using FRC. This research leads to mechanism based structural performance design forcing a tight connection between materials and structural engineering. The approach adopted is combination of experimental and theoretical work. Field data of bridge deck performance and laboratory data of fatigue specimens are emphasized. The nature of this reseach requires combined knowledge of bridge engineering as well as composite materials engineering.