Analytical Model for Bond Behavior Prediction of CFRP-Concrete Joints with End Anchorage

Use of the end anchorages can significantly control the debonding of CFRP-to-concrete bond interface, and improve the bearing capacity of CFRP strengthened concrete member. An analytical model was presented in this paper to predict the bond behavior and debonding process of CFRP-concrete bonded joint with end anchorage. The calculation formulas of bond failure load and effective bond length for anchored CFRP-concrete joint are derived from the proposed analytical model. According to these models and formulas, the influence of different bond lengths on the mechanical behaviors during the debonding process was analyzed. Results show the load-slip curves of end anchored CFRP-concrete joints could be divided into three branches: elastic stage, stable stage, and enhancement stage. As the bond length increases, the plateau length in stable stage increases. Besides, the bond failure load decreased firstly to a lower limit and then increased with the increase of bond length. The effective bond length of CFRP-concrete joint with end anchorage was longer than that of the external bonded joint, and the value of effective bond length for end anchored joint shall be at least 7.2/AB, where the parameters A and B were related to the interfacial properties of bonded joint. Furthermore, a single shear test was carried out on the end anchored CFRP-concrete bonded joint with different bond lengths, to verify the consistency of the proposed model and formulas. The analytical result of load-slip response at the load end, as well as the strain distribution of CFRP material and the bond failure load, was compared with the experimental result. The comparisons showed that the analytical results had a good agreement with the experimental results.