Time-dependent reliability analysis of corrosion-induced concrete cracking based on fracture mechanics criteria

Practical experience and observations suggest that corrosion affected reinforced concrete structures are more prone to cracking than other forms of structural deterioration. Around the world, maintenance and repairs resulting from premature concrete cracking and spalling are associated with very high running cost. Furthermore, the ever-increasing demand for greater load carrying capacity of existing reinforced concrete structure only exacerbate the issue. Consequently, this increases the probability of failure of corrosion-affected reinforced concrete structure. It is therefore vital to study corrosion-induced concrete cracking and to perform a service life prediction to avoid unwanted corrosion-induced failures and develop cost-effective methods for maintenance and rehabilitation of reinforced concrete structures.<br><br>This research attempts to examine the process of concrete cracking and determine the critical crack depth at which a corrosion-induced crack becomes unstable and suddenly propagate to the concrete surface. In the analytical model, a model for corrosion-induced critical crack depth has been derived based on the concept of stress intensity factor. In the numerical model, an extended finite element method has been used to predict the concrete cover capacity based on a maximum principal stress fracture criterion. To validate the developed models, an accelerated corrosion experiment was conducted and the time to corrosion-induced cracking and the growth of crack width was measured. With the developed model, a time-dependent remaining service life prediction for corrosion-induced cracking in RC was conducted.<br><br>It is concluded that the analytical method is one of the very few theoretical methods that can predict with reasonable accuracy corrosion-induced critical crack depth in reinforced concrete. It was also found that the extended finite element method can be used to model the concrete cover capacity which can then be used to predict the time to corrosion-induced concrete cracking.  It was also found that the porous zone in concrete can significantly affect the time to corrosion-induced cracking. It was also found that corrosion rate and concrete cover are the most influencing factors that will affect the remaining service life of corrosion affected reinforced concrete structures. With the developed models in this thesis, the information provided can help asset managers and engineers in making more inform decisions with regards to maintenance and rehabilitation strategies of corrosion affected reinforced concrete structures.