Investigation of the structural behavior of GFRP-reinforced concrete beams exposed to elevated temperatures

This study presents an investigation aimed at understanding the behaviour of the glass fiber reinforced polymer (GFRP) bars under elevated temperatures. For this purpose, reinforced concrete beams with GFRP reinforced bar, and GFRP, steel, and concrete cube specimens gradually heated from 100ºC to 800ºC, and cooled at room temperature, then subjected to loading tests. The results show that, concrete cubes lost 55% of the compressive strength under 600ºC, and 82% at 800ºC; GFRP bars lost 65% of the tensile strength at 400ºC, %90 at 500ºC, and at higher temperatures, they lost all mechanical properties; steel rebars lost 30% of the yield strength at 800ºC. Examinations of the material bond strengths in pull-out tests showed that GFRP bars lost 55% of their slip strength at 500ºC, and lost entire slip strength at 800ºC; steel rebar specimens lost 42% of their slip strength at 600ºC, and the loss increased up to 88% at 800ºC. For GFRP reinforced concrete beam specimens, they lost 48% of their load-bearing capacity at 500ºC, and this loss became 85% when temperature increased to 600ºC. At the bottom line, it was observed that concrete and reinforced concrete systematically affected by elevated temperatures with respect to the bonding of the materials, and bearing capacity, thus, they have significant role under these circumstances.