Efficiency of grooving method used for deficient RC beam-column joints seismically rehabilitated with CFRP sheets

Abstract

Beam-column joints are key members in reinforced concrete (RC) moment frames resisting seismic loads which their failure may lead to total collapse of structure. Application of fiber reinforced polymer (FRP) composites has been received much attention in seismic rehabilitation of these members. However, the main challenge facing this technique is the premature debonding of FRP composites off the concrete substrate posed. Grooving method (GM), as an alternative to the conventional externally bonded reinforcement (EBR) technique, has yielded promising results in postponing, or in some cases eliminating altogether, the undesirable debonding failure mode in the flexural/shear strengthening of beams. The present experimental study was conducted to investigate the effects of GM in the seismic behavior of exterior RC beam-column deficient joints strengthened with CFRP sheets taking advantage of the special technique of externally bonded reinforcement on grooves (EBROG) coupled with FRP fan at termination point of FRP composites in postponing or completely elimination of undesirable debonding failure mode in shear strengthened RC beam-column joints. To do so, three half-scale RC beam-column subassemblies were tested under reversed cyclic lateral load. Results revealed that GM, coupled with FRP fan at termination point of FRP composites, was able to eliminate altogether the debonding failure mode and remarkable improvement in terms of load-carrying capacity, ductility, and energy dissipation was achieved.