Flexural strengthening of code-compliant RC beam-column joints using CFRP

Effectiveness of externally bonded fibre reinforced polymers (FRPs) in order to repair/retrofit of deficient RC beam-column joints has been confirmed in recent years. Code-compliant structures could even benefit from FRP retrofitting if there is any significant change in the usage of the structure or more strict codes are imposed due to some inevitable circumstances. Towards this, an experimental investigation has been conducted on nine small scale (1/2.85) RC beam-column joint specimens; seven of them retrofitted using carbon FRP (CFRP) on top and bottom sides of the beam. The retrofitting design is aimed to increase the flexural strength of beam-column sub-assemblage. In addition, the efficiency of an almost novel technique in precluding the debonding brittle failure and facilitating the flexural moment transmission from beam to columns is investigated. Both monotonic and cyclic loading regimes are implemented to estimate, albeit approximately, the seismic responses of the test specimens. The experimental results in terms of load-displacement curves, ultimate strength, and ductility are compared before and after retrofitting. The outcomes indicate the capability of the suggested retrofitting scheme in not only enhancing the loading capacity, but also the relocation of the plastic hinges away from the column face if specified retrofitting details are implemented.