Repairing and strengthening of earthquake-damaged RC beams with CFRP strips

This paper summarizes the results of an experimental investigation into earthquake-damaged (damaged in shear under cyclic load) reinforced concrete (RC) beams repaired and strengthened by externally bonded carbon fibre-reinforced polymer (CFRP) strips. Eight specimens, apart from the reference beam, were separated into two distinct groups. Four experimental beams in the first group were subjected to cyclic load up to failure then properly repaired and CFRP strengthened. Four undamaged specimens from the second group were repaired and strengthened following the identical scheme as the first group for comparison. This study examines whether earthquake-damaged RC beams that have been repaired and strengthened will demonstrate similar strength and behaviour to equally strengthened, undamaged RC beams. In the absence of steel stirrups, increases of minimum 57% and maximum 72% in shear capacity according to the reference were obtained from the strengthened specimens. Accordingly, a strength similarity with a distinction of 5% according to strengthened specimens was obtained for the repaired and strengthened specimens. Additionally, vertical and inclined CFRP strips were evaluated in the experimental programme to establish which application type is more efficient for repairing and strengthening. Test results confirmed that both strengthening schemes, which were evaluated in the experimental programme, were efficient for repairing and strengthening the specimens with the cracking patterns considered.