Experimental Investigation on Flexural Behavior of RC Beams Strengthened by NSM CFRP Reinforcements

Abstract

Synopsis: This study presents the results of experiments performed on RC (Reinforced Concrete) beams strengthened with NSM(Near Surface Mounted) reinforcement. A total of 8 specimens have been tested. The specimens can be classified into EBR(Externally Bonded Reinforcement) specimens and NSM(Near Surface Mounted) reinforcements specimens. Two of NSM specimens were strengthened with 12 mechanical interlocking grooves with a width of 20 mm and spacing of 200 mm in order to prevent debonding failure of the CFRP(Carbon Fiber Reinforced Polymer) reinforcement. Experimental results revealed that NSM specimens used CFRP reinforcements more efficiently than the EBR specimens, but debonding failure between adhesive and concrete occurred. This showed that, similarly to EBR specimens, NSM specimens also required countermeasures against debonding failure. Failure mode of NSM specimens added with mechanical interlocking grooves failed by rupture of CFRP rod and strip. The measured ultimate load showed an increase of 15% compared with the common NSM specimens. The application of mechanical interlocking grooves made it possible to avoid debonding failure and to enhance strengthening performance.