Retrofitting of Reinforced Concrete Beam-Column Joints by Composites—Part II: Analytical Study
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 study, 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.
Keywords: analytical
model; beam-column joints; carbon fiber-reinforced polymers (CFRPs);
joint capacity; joint failure mechanisms; reinforced concrete; shear
strengthening
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