Experimental Investigation of the Efficacy of EBROG Method in Seismic Rehabilitation of Deficient Reinforced Concrete Beam–Column Joints Using CFRP Sheets

Abstract

A major cause underlying the collapse of reinforced concrete (RC) moment-resisting frames observed in past earthquakes is the shear failure of nonseismically detailed exterior beam–column joints. A number of studies have investigated the external application of fiber-reinforced polymer (FRP) composites for the seismic rehabilitation of these members. However, the main challenge facing this technique is the premature debonding of FRP composites off the concrete substrate posed. The 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 carbon-FRP (CFRP) sheets taking advantage of the special technique of externally bonded reinforcement on grooves (EBROG). Another facet of the study is the investigation of the performance of FRP fans in preventing the splitting failure of the concrete cover. For the purposes of this study, six half-scale RC beam–column subassemblies with no transverse reinforcement in the joint region were constructed. Results revealed that the EBROG technique, coupled with FRP fans at the termination point of FRP sheets, was able to eliminate altogether the debonding. It was, further, able not only to delay the brittle shear failure of the beam–column joints but also to relocate the beam plastic hinge away from the column interface under specific circumstances. Moreover, it was found that application of CFRP composites via the EBROG method was able to produce a significant enhancement in the seismic capacity of the test specimens in terms of their strength, stiffness, ductility, pinching width ratio, and energy dissipation.