Experimental study of external bonded CFRP-concrete interface under low cycle fatigue loading

The main problem with carbon fibre reinforced polymers (CFRPs) in reinforcement is the bonding of the reinforcement to the concrete because the failure generally occurs by debonding. In the case of seismic loading, a high level of stress with cyclic loading may appear in the adhesive zone that's why this study focuses on the low-cycle fatigue of a concrete/CFRP interface under a high level of shear stress. It focuses on the influence of the fatigue loading amplitude on the service life (number of cycles prior to failure). This paper presents the results of an experimental campaign conducted on double shear test, an analysis of the failure mechanism, and the development of an analytical model to predict the lifetime of a CFRP/concrete interface. We studied two different CFRPs, one based on a unidirectional textile, composite A, and the other reinforcement based on a bidirectional textile (with a 70/30 ratio), composite B. The results of this study will allow the development of an empirical model based on Wohler's fatigue law describing the fatigue life of a CFRP-concrete interface as a function of the imposed fatigue loading amplitude. Once validated and enhanced, this empirical model will make it possible to predict and therefore reduce the risk of disbonding.