Cyclic Loading Behavior of CFRP-Wrapped Non-Ductile Beam-Column Joints

摘要

Use of fiber reinforced polymer (FRP) material has served as a proper solution to overcome the weakness of concrete members caused by substandard design, changes in the load distribution, or to correct the weakness of concrete structures subjected to hostile weather conditions. Concrete beam-column joints designed and constructed before 1970s were characterized by weak joints. Lack of transverse reinforcement within the joint reign, hence lack of ductility in the joints could be one of the main reasons that many concrete buildings have failed during earthquakes around the world. In the present work, carbon fiber reinforced polymer (CFRP) sheets were used as Externally Bonded FRP System to compensate for the lack of transverse reinforcement in the beam-column joints in order to retrofit the joint region and to transfer the failure to the concrete beams. Six specimens of approximately one-third scale were designed, constructed, and tested. A new technique of rehabilitation scheme is proposed for retrofitting. The scheme proved to be effective in improving the behavior of non-ductile beam-column joints, and to change the final mode of failure. The comparison between beam-column joints before and after retrofitting is presented by load versus deflection, load versus CFRP strain, energy dissipation, and ductility.