Experimental study of CFRP-to-concrete bonded joints under fatigue loading

Externally bonded (EB) FRP strengthening of reinforced concrete (RC) structures has gained popularity worldwide because of its many advantages compared to conventional strengthening methods. Performance of the structures strengthened using EB FRP laminates depends significantly on the performance of the bonded interface between the FRP and concrete. Therefore, extensive research has been carried out to study the behaviour of FRP-to-concrete bonded joints, and numerous theoretical models have been developed to predict the behaviour of such bonded joints under monotonic loading. However, only limited research efforts have been made on understanding and modelling the behaviour of FRP-to-concrete bonded joints under fatigue cyclic loading. This paper presents the results of an experimental study aimed at investigating the behaviour of FRP-to-concrete bonded joints under fatigue cyclic loading. A customized data acquisition system was developed to capture the axial strains of FRP plate during fatigue cyclic loading. From the test results, it was observed that the loading amplitude, concrete strength and the type of the CFRP plate used significantly affected the failure mode of FRP-to-concrete bonded joints under fatigue cyclic loading