Use of FRP for RC Frames in Seismic Zones: Part I. Evaluation of FRP Beam-Column Joint Rehabilitation Techniques

Multi-storey reinforced concrete frames that were built prior to the 1970's generally do not meet current seismic design code requirements. The lateral load carrying capacity of these structures is often insufficient due to non-ductile reinforcement detailing, which includes either insufficient or no beam-column joint transverse reinforcement. It was observed during recent earthquakes that deficient beam-column joints can jeopardise the integrity of entire structures. Thus, several beam-column joint rehabilitation techniques have emerged to upgrade such substandard joints. It is essential to evaluate the standings of joints rehabilitated with such techniques based on current design code requirements.This paper critically examines beam-column joint rehabilitation techniques using FRP that emerged in the last decade. For this purpose, a full-scale code-conforming beam-column joint was made and tested under reversed cyclic load to serve as a benchmark for this comparison. Enhancements imparted to substandard beam-column joints by FRP rehabilitation techniques in terms of strength, ductility and energy dissipation gains are assessed. It is shown that FRP joints repair schemes generally enhanced the performance of substandard joints, but they often came short of satisfying current standard level performance, and that different rehabilitation strategies can be adopted depending on the type of joint deficiency and the purpose of the rehabilitation scheme.