Retrofitting of Reinforced Concrete Beam-Column Joints by Composites-Part II: Analytical Study

Abstract

Beam-column joints (BCJs) in reinforced concrete (RC) structural systems are the critical regions, especially when they are subjected to high shear demands. According to earthquake reports and joint subassembly tests in the literature, mostly brittle failures were experienced due to inadequate design detailing. To avoid such failures, several strengthening techniques were developed for weak BCJ regions such as externally applied steel and RC jackets, and fiber-reinforced polymer (FRP) materials. Experimental results revealed alleviation of these deficiencies and improved shear capacities of the strengthened joints. Shear capacity predictions of these retrofitted joint subassemblies for design purposes require analytical models. In this stu dy; an analytical model and computation procedure was proposed to predict the lateral load capacities of the shear-critical joint subassemblies with or without carbon fiber-reinforced polymer (CFRP) wrapping technique. Several failure mechanisms such as shear failure in joint panel, crushing of concrete in the beam, yielding of the beam reinforcement, or rupture of CFRP wrapping were determined for each incremental lateral load level and most critical ultimate lateral load capacity was found. The predicted results were compared with the experimental results in Part I of this paper as well as other research in the literature, and they were in good agreement.