Combined cohesive-bridging zone model for prediction of the debonding between the FRP and concrete beam interface with effect of adherend shear deformations

Prediction of the IC debonding failure of FRP-strengthened RC beams based on the cohesive zone model

“…The existing IC debonding prediction models of FRP-strengthened plain concrete beams based on the CZM all derive the interface shear stress distribution law by defining a nonlinear interface bond-slip relationship (Wang, 2006a;Wang, 2006b;Chen and Qiao, 2009;Hadjazi et al, 2012;Houachine et al, 2013;Hadjazi et al, 2016;Bennegadi et al, 2016); thus, the bond slip curve (τ δ − curve for short, whereτ is the Interfacial shear stress and δ is the relative size of the slip) plays an important role in the prediction of IC debonding. The constitutive relation of the FRP-concrete interface is described by the bilinear model ( Figure 5), which is widely used to define the interface behavior of FRP-strengthened RC beams due to it being convenient for use and accurate prediction of interface debonding (Liu et al, 2007;Faella et al, 2008;Shukri et al, 2018;Razaqpur et al, 2020).The constitutive equations for the slip law expressed by the following equations:…”

“…After determining the relationship between the spring rotation stiffness and the interface bond-slip relationship, the debonding between FRP and concrete can be analyzed by nonlinear fracture mechanics method, which takes into account the coupling effect of several parameters. Although such models have been continuously improved in the past 10 years (Bennegadi et al, 2016;Chen and Qiao, 2009;Hadjazi et al, 2012;Houachine et al, 2013;Hadjazi et al, 2016), these analytical model is always created to quantitatively analyze the relationship between interface shear stress and the debonding failure of the FRP-strengthened linear elastic pre-cracked plain concrete beams. In such studies, the flexural cracks are pre-set before loading begins, and the effect of steel reinforcement and the nonlinear behavior of the strengthened beam are not considered.…”

Size effect on the methodology with cylinder specimens for FRP-to-concrete debonding analysis

“…Some advantages, compared to the use of other strengthening materials, are that FRP are noncorrosive, they are materials with high strength-to-weight [12], [13], and high stiffness-to-weight [1], [2], [14]- [16] ratios. However, there are some questions about failure modes, in particular the collapse at the interface, which occurs by means of FRP and concrete debonding in regions of high stress concentrations.…”