Experimental Study on the Thermo-Mechanical Behavior of Hand-Made Carbon Fiber Reinforced Polymer (H-CFRP) Simultaneously Subjected to Elevated Temperature and Mechanical Loading

Among two common forms of CFRP used in strengthening/repairing construction structures (pultruded and hand-made), hand-made CFRP is popularly used with column and other structures where the strengthening surfaces are complicated. Normally, the hand-made CFRP (H-CFRP) includes woven carbon fibers, prefabricated in the factory and the polymer matrix which is added during the installation process. When a fire happens, structures and reinforced material are simultaneously exposed to high temperatures (up to 1200 °C) and mechanical loadings, which are complicated and difficult to be experimentally simulated. As far as the authors concern, the studies of CFRP and structure reinforced with CFRP in fire are rare due to expensive cost of experiments and insufficient theoretical calculations. For these reasons, this study aims to investigate the thermo-mechanical behavior of H-CFRP via two different elevated-temperature and mechanical load regimes. The first regime studies the ultimate-strength evolution as the exposed temperature increases while the second studies the variation of rupture temperature when applied load changes. The results from the first regime show that the ultimate strength and the Young modulus of H-CFRP generally reduce 50% and 25% when the applied temperature level increases from 20 °C to 400 °C. The second series show that the rupture temperature of H-CFRP steadily reduces from about 640 °C to about 467 °C as its mechanical stress ratio increases from 0.1 to 0.5 (of its ultimate strength at 20 °C). Remarkably when the mechanical stress ratio of H-CFRP increases to 0.75, the rupture temperature dramatically drops to about 50 °C. The rupture modes and correlation between two regimes will also be discussed.