Strengthening reinforced concrete (RC) beams with openings by using aramid fiber reinforcement polymers (AFRP)\non the beamsââ?¬â?¢ surfaces offers a useful solution for upgrading concrete structures to carry heavy loads. This paper presents a\nrepairing technique of the AFRP sheets that effectively strengthens RC beams, controls both the failure modes and the stress\ndistribution around the beam chords and enhances the serviceability (deflection produced under working loads be sufficiently small\nand cracking be controlled) of pre-cracked RC beams with openings. To investigate the possible damage that was caused by the\nservice load and to simulate the structure behavior in the site, a comprehensive experimental study was performed. Two unstrengthened\ncontrol beams, four beams that were pre-cracked before the application of the AFRP sheets and one beam that was\nstrengthened without pre-cracking were tested. Cracking was first induced, followed by repair using various orientations of AFRP\nsheets, and then the beams were tested to failure. This load was kept constant during the strengthening process. The results show\nthat both the preexisting damage level and the FRP orientation have a significant effect on strengthening effectiveness and failure\nmode. All of the strengthened specimens exhibited higher capacities with capacity enhancements ranging from 21.8 to 66.4%, and\nthe crack width reduced by 25.6ââ?¬â??82.7% at failure load compared to the control beam. Finally, the authors present a comparison\nbetween the experimental results and the predictions using the ACI 440.2R-08 guidelines.
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