Single-shear test of CFRP plate-ECC-concrete composite interface

To solve the problems of CFRP plate being easy to peel off from concrete of concrete structure strengthened with carbon fiber reinforced polymer (CFRP) plate and the limited increase of bearing capacity of concrete structure strengthened with engineered cementitious composites (ECC), the CFRP plate-ECC-concrete composite interface was proposed to take full advantage of both the high tensile strength of CFRP plate and good durability of ECC with multiple cracking. 21 single-shear specimens with different ECC thickness and concrete/ECC strength were designed and tested. The distribution of interface load-carrying capacity, strain distribution, and bond-slip curve of specimens were obtained. The result shows that the failure pattern of all specimens with ECC layer is the debonding failure which occurs in the interface between the CFRP plate and ECC. It demonstrates that the ECC layer can obviously delay the debonding of CFRP plate, meanwhile, transfer the interfacial shear stress effectively. Compare with the specimens without ECC layer, the ultimate load-carrying capacity of specimens with ECC layer increases by 27.3%-59.6%. Based on the Lu Xinzheng’ ultimate load-carrying capacity calculation model, a prediction model of the load-carrying capacity of single-shear specimens considering the thickness of ECC was proposed, and the calculated value is consistent with the experimental results. Different bond-slip models were adopted to analyse the test results and the comparison shows that: Ferracuti et al model considers more comprehensive factors and fits better with the test results than other models.