Numerical Modeling of Response of CFRP–Concrete Interfaces Subjected to Fatigue Loading

Abstract

For interfaces between externally bonded fiber-reinforced polymer (FRP) laminates and concrete, the incremental fatigue analysis for each load cycle using a finite-element (FE) model is exceptionally time-consuming. This study introduces an accurate and efficient numerical approach that accounts for the bond–slip effect under fatigue loading. A preload cycle was adopted to model the damage caused by the previous load cycles. The formulae for the upper limit of the preload and the unloading stiffness in the local bond–slip model were established. The reloading and unloading stiffnesses in the bond–slip model for an arbitrary load cycle were defined. Moreover, different bond–slip models were adopted for a numerical analysis to compare the effect of the bond–slip relations on the fatigue response of a carbon FRP (CFRP)-strengthened concrete structure. The comparisons between the numerical results and the experimental data show that the proposed approach is capable of accurately predicting the fatigue response of CFRP-strengthened structures. The debonding process of the CFRP plate from the concrete surface under fatigue loading can be predicted by the proposed model. Compared with the existing bond–slip models, the proposed model in this study is more effective in predicting the mechanical response of the CFRP-to-concrete interfaces subjected to fatigue loading.