Fiber Reinforced Polymer Repair Techniques for Reinforced concrete Beams Pre-Damaged in Shear

Abstract

Nowadays FRP (fiber reinforced polymers) has been widely used for both strengthening and repair of reinforced concrete (RC) members. FRPs were first used in seismic retrofitting of RC columns by wrapping. FRPs were then used in the flexure strengthening of RC beams and slabs, later they were used in the shear strengthening of RC beams. Typically Carbon or glass fiber sheets externally bonded to the bottom and sides of RC beams were used for the shear strengthening of RC beams. Another technique, previously proposed by the authors, is to strengthen RC beams in shear by drilling holes through the depth of the beams and then embedding FRP rods in these holes. In this paper a comparison of these two techniques in strengthening and repairing RC beams is presented. Six beams were tested; a control beam without strengthening, two beams strengthened using externally bonded CFRP (Carbon Fiber Reinforced Polymer) sheets and two beams strengthened using embedded CFRP rods. For each technique one specimen was preloaded beyond the formation of the first crack before strengthening while the other was not preloaded in order to study the effects of preloading. The last specimen was the control specimen which was retrofitted after being loaded to failure in shear then retested again after repair. Preliminary findings from this on-going work and some recommendation for  the use of FRP to strengthen concrete structures as a mainstream technology throughout the world where a specific research projects should be aimed for better understanding to the underlying  mechanics of this techniques are outlined here.