Seismic behaviour of deficient RC frames strengthened with CFRP composites

A full-scale two-storey RC building with poor detailing in the beam–column joints was tested on a shake table as part of the European research project ECOLEADER. After the initial tests which damaged the structure, the frame was strengthened using carbon fibre reinforced materials (CFRPs) and re-tested. This paper investigates analytically the efficiency of the strengthening technique at improving the seismic behaviour of this frame structure. The experimental data from the initial shake table tests are used to calibrate analytical models. To simulate deficient beam–column joints, models of steel–concrete bond-slip and bond-strength degradation under cyclic loading are considered. The analytical models are used to assess the efficiency of the CFRP rehabilitation using a set of medium to strong seismic records. The CFRP strengthening intervention enhanced the behaviour of the substandard beam–column joints, and resulted in substantial improvement of the seismic performance of the damaged RC frame. It is shown that, after the CFRP intervention, the damaged building would experience on average 65% less global damage compared to the original structure if it was subjected to real earthquake excitations.