Bond-slip models for CFRP plates externally bonded to steel substrates

This paper examines the development of the bond-slip models for carbon fiber reinforced polymer (CFRP) plates externally bonded to steel substrates where debonding failure occurs in the adhesive layer. Thirteen single-shear bonded joints were tested to investigate the effects of the adhesive properties and the adhesive thickness on the bond-slip behavior of the interfaces. The test results showed that the bond-slip relationship for the bonded joints with the Sikadur-30 adhesive was approximately triangular, whereas that with the Araldite-2015 adhesive can be simplified to a trapezoidal shape. Based on a careful analysis of a database of CFRP-to-steel bonded joints, expressions were formulated for the key parameters employed in the triangular and trapezoidal bond-slip models, including the interfacial fracture energy G f , the peak interfacial shear stress τ max , and the relative slip indexes s 1 , s 2 and s f . The influences of the adhesive properties and the adhesive thickness were accounted for in the proposed models. The comparisons between the predicted and test results showed that the predicted results have good agreement with the collected test data and that the proposed models have reasonable accuracy. The proposed bond-slip models are expected to be useful in the theoretical modeling of CFRP plate-strengthened steel members.