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


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

Author(s): W.-T. Jung, Y.-H. Park, J.-S. Park, J.-Y. Kang, and Y.-J. You

Publication: Special Publication

Volume: 230


Appears on pages(s): 795-806

Keywords: carbon fiber reinforced polymer; externally bonded CFRP reinforcements; near surface mounted CFRP reinforcements; strengthening

Date: 10/1/2005

This study presents the results of experiments performed on RC (ReinforcedConcrete) beams strengthened with NSM(Near Surface Mounted) reinforcement. A totalof 8 specimens have been tested. The specimens can be classified into EBR(ExternallyBonded Reinforcement) specimens and NSM(Near Surface Mounted) reinforcementsspecimens. Two of NSM specimens were strengthened with 12 mechanical interlockinggrooves with a width of 20 mm and spacing of 200 mm in order to prevent debondingfailure of the CFRP(Carbon Fiber Reinforced Polymer) reinforcement. Experimentalresults revealed that NSM specimens used CFRP reinforcements more efficiently thanthe EBR specimens, but debonding failure between adhesive and concrete occurred.This showed that, similarly to EBR specimens, NSM specimens also requiredcountermeasures against debonding failure. Failure mode of NSM specimens addedwith mechanical interlocking grooves failed by rupture of CFRP rod and strip. Themeasured ultimate load showed an increase of 15% compared with the common NSMspecimens. The application of mechanical interlocking grooves made it possible toavoid debonding failure and to enhance strengthening performance.