Experimental Investigation on the Seismic FRP Retrofit of Realistic Full-Scale RC Beam-Column Joints

The results of four cyclic tests on full-scale beam-column joints with typical pre1970s deficiencies are presented. The challenges incurred by the presence of a floor slab and transverse beams in retrofitting deficient specimens are often ignored, but are here fully taken into account in the experimental set-up. A realistic repair and retrofit scheme using carbon fibre-reinforced polymer (CFRP) sheets is proposed. The scheme aims to improve the ductility of the deficient joints, while providing continuity of the flexural strengthening through the joint. The results highlight that the proposed retrofit can successfully increase the ductility of the joint by activating the beams. The presence of the slab has a significant effect on the global behaviour of the sub-assembly, which ultimately does not reach failure in the beams due to the stiff slab limiting rotation. Despite significant pre-damage, the repair scheme is very efficient, with only minor differences in terms of initial stiffness and lateral strength compared to the retrofit.