The effect of fatigue loading on the behavior of externally bonded CFRP-to-concrete joints using the grooving method

Grooving methods (GM) have remarkably shown higher efficiency than externally bonded reinforcement (EBR) in anchoring the fiber-reinforced polymers (FRP) used for retrofitting concrete structures. The behavior of the EBR and GM installation methods were evaluated in many studies, however the behavior of grooving methods under fatigue loading has not been assessed yet, and the present study is the first attempt to achieve the above aim. Accordingly, three concrete slabs with the dimension of 650×650×200 mm3 were strengthened using carbon FRP (CFRP) sheets bonded via the EBR and grooving methods and then tested by a single lap-shear setup. Furthermore, the bond behavior of CFRP strips-to-concrete substrate was investigated in this research in terms of the load capacity, slip, and debonding mechanism. The results showed that the grooving method improved the bond properties of CFRP-to -concrete joints under fatigue loading. By using this alternative technique, the number of cycles until failure (fatigue life) increases incredibly under the same fatigue cycle loading and the service life of strengthened members could be improved under fatigue loading.