Analysis Of Corrosion-induced Expansive Cracking Of Concrete Cover Based On Fracture Mechanics Approach

With the increasing need of developing service life models for corrosin-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 residual tensile capacity once the tensile strength behaviour of concrete beyond cracking initiation. This thesis proposes such a model wherein the state stress of the concrete cover due to accumulation of corrosin prodcts is determined by analyzing an equivalent thick-wall cylinder subject to a uniform internal pressure. Concrete is assumed to be an isotropic material, and deformations due to Poisson's ratio are ignored. To descibe the behaviour of concrete in the softening region, a relation of stress versus displacement and a constant strain field are assumed. Mathematical experssions that determind 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 longitdinal cracking of the concrete cover are formulated for unconfined conditions. To determine the validity of these models, their results are compared to published experimental data. Finally, a parametric 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.