Seismic response of FRP-strengthened corner RC beam-column joints

In the present paper an innovative and practical technique for the seismic rehabilitation of poorly detailed beam-column corner joints using FRP composite sheets has been proposed. A full scale corner beam-column sub-assemblage was constructed with inadequate joint shear strength and no transverse reinforcement in the joints representing pre-seismic code design construction practices of joints and encompassing the vast majority of existing joints. The corner joint specimen was tested under reversed cyclic lateral load histories so as to provide the equivalent of severe earthquake damage. The damaged specimen was repaired using a suggested scheme and then subjected to the similar cyclic lateral load history. Response histories of the specimen before and after repair were then compared through hysteretic loops, load-displacement envelopes, ductility and stiffness degradation. The test results indicated that the suggested repair scheme is very effective in upgrading the shear capacity and ductility of the joint. The results also show that, with the proposed FRP scheme of repair, the repaired specimen achieves a substantially higher load carrying capacity, higher ductility and slower stiffness degradation.