Effect of high-stress level loads on the fatigue performance of GFRP-RC beams

GFRP (Glass fiber reinforced polymer) reinforced concrete (GFRP-RC) structures are often used in harsh engineering environments to replace steel bars to resist environmental corrosion. Due to the low fatigue stiffness of the GFRP-RC structure, the structure is prone to failure due to excessive fatigue deformation after experiencing high-stress level loads such as tsunamis and earthquakes. In order to further study the characteristics of the mechanical performance of GFRP-RC beams under high fatigue stress levels, this paper carried out fatigue tests on 10 GFRP-RC beams at fatigue stress levels (S) of 0.85, 0.70, 0.65, and 0.60. The results show that the fatigue stress level can affect the failure mode of GFRP-RC beams, and high-stress loading is prone to inclined section failure. Otherwise, vertical cracking failure will occur. Increasing the fatigue stress level will not affect the damage growth rate during the stable stage of fatigue. However, it will exacerbate the accumulation of structural damage and the degree of fatigue stiffness degradation. In addition, the applicability of three existing fatigue deflection prediction models in GFRP-RC structures was also checked by experimental data, and it was found that only the CEB-FIP model had a higher accuracy.