Full-Scale Experimental Investigation of Repair of Reinforced Concrete Interstate Bridge Using CFRP Materials

An experimental study is presented of the behavior of eight reinforced concrete bridge girders taken from a decommissioned Interstate bridge and retrofitted with three different carbon-fiber-reinforced polymer (CFRP) systems. Specimens were subjected to monotonic loading to failure with and without significant fatigue conditioning. Experimental observations indicated that intermediate crack-induced debonding was the dominant failure mode for monotonically loaded beams and that degradation of the CFRP-to-concrete interface was caused by fatigue conditioning. Conventional adhesive applied and near-surface mounted (NSM) CFRP systems behaved well under monotonic loads, with the NSM system exhibiting significantly greater ductility. Powder actuated fastener applied retrofit was observed to be less efficient, requiring a relative slip of the CFRP in order to engage the shear transfer mechanism of the fasteners. The application of current accepted design guidelines for FRP retrofit indicated that guidelines aimed at mitigating debonding failure appear to be appropriately conservative under monotonic loading conditions; however, a significant additional reduction in CFRP strain limits is required to account for even small levels of fatigue loading.