The Experimental Study of the Effect of FRP Laminates on Shear Strength of RC Fixed Ended Deep Beams

Very little researches hasbeen performed about strengthening and repairing of deep beams. In this paper, shear strength of Reinforced Concrete (RC) deep beams in two cases of repair and strengthening with Carbon Fiber Reinforced Polymer (CFRP) is evaluated. To achieve the objective of the research, six deep beams were constructed in three coupling groups with constant reinforcement arrangement and concrete strength and clear span-to-depth ratio of 2. In each group, one beam without strengthening was used as reference beam. This beam was loaded up to failure and then reinforced by CFRP and reloaded again. The other one was reinforced before loading, similar to the first one. The results indicated that repair and strengthening the beams would increase the ultimate load. In general, when one directional CFRP strip is attached to the face of the beams perpendicular to crack with the angle of 45o (SS45), the ultimate strength is increased by 7 and 61%, respectively. Therefore it can be conclude that SS45 system because of uniform distribution of CFRP perpendicular to the direction of shear cracks, could be the best method for repair and strengthening of tested fixed ended deep beams and in comparison with reference beam, if it used to repair the damaged beam, the ultimate load would increase up to 7 percent.