Effect of Long-term Thermal Conditioning on GFRP-RC Beams
Jahanzaib and Shamim A. Sheikh
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Results from an experimental program consisting of 10 large beams are presented herein that investigated the behavior of reinforced concrete (RC) beams reinforced with glass fiber-reinforced polymers (GFRP) bars, before and after thermal conditioning. All the beams were completely reinforced with GFRP bars. Control beams tested at room temperature were designed to investigate the flexural behavior of the most-recent generation of GFRP straight bars as well as stirrups. Thermal treatment was designed to study the long-term durability of GFRP-RC beams considering the recent climate challenges of continuously increasing temperatures across the North American regions. Beams were conditioned at 50°C for 4 months under 60% relative humidity and were subjected to sustained load throughout the conditioning duration. Test results of the control beams showed that GFRP-RC beams can show significant increase in the ultimate failure load when appropriately confined in the flexure zone with transverse reinforcement. Deterioration of beams’ behavior was studied as a result of thermal conditioning, especially for stages related to concrete crushing as well as ultimate failure. Under-reinforced beams designed to fail in bottom bars’ rupture showed approximately 22% reduction in the ultimate failure load due to conditioning, but over-reinforced beams did not observe substantial reductions in the ultimate capacity although the load corresponding to initiating of concrete crushing reduced by approximately 10%.