A new bond-slip model for adhesive in CFRP–steel composite systems

Debonding of CFRP from steel surface is an important issue in the field of strengthening of steel structures. In this paper, a new method for analysis of bonded connections of CFRP and steel substrates is presented. This method simulates the connection via a series of equivalent discrete springs. In this approach, simple closed-form solutions are derived to calculate total elastic stiffness as well as effective elastic bond length of a plate bonded to a rigid substrate. Furthermore, a new bond-slip model is suggested by adding a plastic part to the previous bond-slip curve. In this model, initial stiffness is determined from elastic properties of adhesive. Two other parts are defined in such a way that the area under the curve is equal to interfacial fracture energy. Comparison of results obtained from the proposed model and experimental data shows that ultimate debonding load may be accurately estimated by the proposed model. In addition, load–displacement curve obtained by the present model is quite comparable to experimental curves. Moreover, effective bond length shows good agreement with those determined from experimental tests. In this model, unlike some previous bond-slip models, ultimate debonding load is independent from adhesive thickness.

► A new method for analysis of bonded connections of CFRP and steel substrates is presented.
► A new bond-slip model is suggested by adding a plastic part to the previous bond-slip curve.
► In this model, unlike previous bond-slip models, ultimate debonding load is independent from adhesive thickness.