Effect of fatigue loading on flexural performance of NSM CFRP-strengthened RC beams under different service temperatures

Abstract

This paper presents an experimental work to investigate the effect of fatigue loading and high service temperature on the flexural performance of near-surface mounted (NSM) carbon fiber reinforced polymer (CFRP)-strengthened reinforced concrete (RC) beams. The experimental program included 11 beams, where the effect of the strengthening (CFRP) ratio (0.06 % and 0.18 %), fatigue load level (R1 = 0.57 and R2 = 0.38) and applied temperature (20 °C and 70 °C) have been considered. Experimental results on fatigue tests showed that high service temperature resulted in an increase in deflections and reduction in the stiffness of the specimens along the test. Moreover, the application of fatigue cycles with larger amplitude resulted in the failure of the specimens (by steel rupture), whilst specimens submitted to lower fatigue amplitude survived to the fatigue cycles. The NSM CFRP-strengthening helped to postpone the final failure of strengthened RC beams after steel reinforcement rupture during the fatigue test. Besides, damage due to fatigue derived in lower residual yielding and ultimate load in the post-fatigue test.