Retrofitting of partially damaged reinforced concrete beam-column joints using various plate-configurations of CFRP under cyclic loading

This paper presents an experimental work on repair of partially damaged reinforced concrete beam- column joints using carbon fiber-reinforced plastics (CFRP) plates. The investigation carried out is mainly dedicated to study the behavior of repaired RC beam-column joints under cyclic loading with a variety of retrofitting schemes. Eight specimens were prepared and tested to investigate the repairing efficiency for improving strength-capacity, stiffness and behavior of partially damaged RC joints. The control specimen was tested up-to-failure under cyclic loading. Seven specimens were loaded up-to a certain load level which was about 80% of expected failure load (known as preload). Then, they were retested after repairing using various schemes of CFRP-plates. The results were examined through load versus drift-ratio; initial-stiffness of curve, ductility index and maximum load. Besides, strains in CFRP-plates were measured and the failure modes of the test specimens; due to crack-pattern and CFRP-debonding, were monitored. The results showed the important issue of repairing and enhancing the joint-performance and hence delaying premature debonding of the various CFRP-configurations. All repaired joints show improved strength, which reached almost the existing shear-strength of the beam-column joint. Hence, the resulted repaired joints enhanced a much larger strength-capacity than the reference joints.