Study on crack propagation behavior between CFRP and concrete under fatigue loading

The purpose of this research was to experimentally investigate the carbon-fiber-reinforced polymer (CFRP)-concrete interface crack propagation behavior in concrete structures externally bonded with CFRP under fatigue loading. According to elastic fracture mechanics, the energy release rate was adopted to describe the growth of cracks. Based on this method, a growth-rate model for interface fatigue cracks induced by flexural cracks in CFRP sheet strengthened beams was developed according to the experimental results of fatigue tests of CFRP sheet strengthened concrete beams. The results show that, evolution of interface fatigue cracks has three stages, including crack initiation and rapid propagation, slow propagation and instability propagation. The interface fatigue crack propagation rate decreases with the increase of load cycles before instability propagation. The relationship between the interface fatigue crack propagation rate and G/Gc (G and Gc are the amplitude of the energy release rate and fracture energy respectively) can bedescribed by Paris equation. It is indicated by comparing the calculated results of the model with test results that, the model can accurately predict the full process of CFRP sheet-concrete interface crack propagation. ©, 2014, Science Press. All right reserved.