Fiber-Reinforced Polymer Strengthening of Concrete Bridges that Remain Open to Traffic

This paper describes a study of traffic loads applied to a reinforced concrete bridge during and after its strengthening with externally bonded fiber-reinforced polymer (FRP) reinforcement. In a laboratory, eight beams were tested. Seven of them were strengthened with a precured, unidirectional, carbon-fiber laminate strip that represented the materials used on the actual bridge. The variables tested included the intensity and frequency of load cycles applied during the epoxy-curing period, the thickness of the epoxy layer, and the thickness of the FRP strip. All these beams failed initially with the FRP debonding in the maximum moment region. For all of the traffic loads applied during and after installation no reduction in strengthening was seen. The experiment concluded that concrete bridges can be strengthened effectively even if they remain open to traffic during the procedure.