Interfacial bond-slip degradation relationship between CFRP plate and steel plate under freeze-thaw cycles

•A set of loading device was designed to test CFRP-steel single-shear specimen.•The degradation models for the bond-slip parameters were formulated by introducing the damage factors.•The CFRP-steel interfacial bond-slip degradation relationships under different freeze-thaw cycles were developed. The bond-slip degradation relationship of a carbon fiber reinforced polymer (CFRP)-steel bonded interface is crucial for predicting the long-term behavior of CFRP-strengthened steel structure under a freeze-thaw (F-T) environment. A total of 16 single-shear bonded joints were tested to investigate the effect of the bond length and the F-T cycles on the CFRP-steel bonded interfaces. The strains on the CFRP surface and the relative slips between the CFRP plate and steel plate were measured by using three-dimensional digital image correlation (3D-DIC) technology. The main properties of the bonded joints were examined, including the failure mode, the ultimate load, the load-slip curve, the CFRP strain distribution and the bond-slip relationship. The degradation models for the bond-slip parameters were formulated by introducing the damage factors, and the interfacial bond-slip degradation relationships were subsequently developed. Finally, the proposed degradation relationship was validated through comparison with the experimental bond-slip relationships and the predicted relationships under different F-T cycles.