Modeling reinforced concrete cracking due to corrosion with a fracture mechanics approach

With the increasing need of developing service life models for corrosion-induced damage in reinforced concrete structures, there has been a movement to model the concrete cover as a thick-wall cylinder subjected to an internal pressure due to corrosion products accumulation on the reinforcing steel. These models allow determining the amount of corrosion product necessary to initiate and propagate cracks along the cover. The first generation of models assume that concrete behaves linearly elastic and that the concrete cover does not have any residual tensile capacity once the tensile strength of the concrete has been reached. More advanced models include the softening behaviour of concrete beyond cracking initiation. This thesis proposes such a model wherein the state stress of the concrete cover due to accumulation of corrosion products is determined by analyzing an equivalent thick-wall cylinder subjected to a uniform internal pressure. Concrete is assumed to be an isotropic material, and deformations due to Poisson's ratio are ignored. To describe the behaviour of concrete in the softening region, a linear relation of stress versus displacement and a constant strain field are assumed. Mathematical expressions that determine the state of stress due to corrosion build-up at any point in the concrete cover are obtained by integrating the softening equations along the concrete cover. Analytical models for cracking initiation as well as longitudinal cracking of the concrete cover are formulated for both unconfined and confined conditions. The latter are the result of the presence of shear stirrups or tie/spiral reinforcement. To determine the validity of these models, their results are compared to published experimental data and finite element analyses. Finally, a parameterc analysis using the models is carried out in order to establish the role of significant model parameters on the resulting state of stress of the concrete cover and the associated damage.