Upgrading cyclic response of heat-damaged RC beam-column joints using CFRP sheets

Abstract

In this study, experimental work is used to determine the efficacy of carbon fiber reinforced polymer (CFRP) sheets, which are used as externally bonded reinforcement in recovering the structural performance and mitigating the failure mechanism of heat-damaged reinforced concrete (RC) beam-column joints. Twelve RC beam-column joints were cast in-house and classified into three batches: four joints were kept at ambient temperature, four joints were subjected to 400 °C temperature, and four joints were subjected to 600 °C temperature. Following the addition of one, two, or three layers of CFRP sheets for reinforcement, three joints from each batch were tested under a quasi-static cyclic load. The ultimate load capacity in pulling and pushing, as well as its corresponding lateral displacement, horizontal load-lateral displacement envelopes, energy dissipation, displacement ductility, and stiffness degradation, were all considered while evaluating the structural performance of the joints. The experimental results showed that the cyclic performance of heat-damaged RC beam-column joints strengthened with CFRP sheets had improved (greater lateral displacement, higher load capacity, higher energy dissipation, higher displacement ductility, and slower secant stiffness degradation). Additionally, when heat damage increases in severity, CFRP sheets become more effective.