| An integrated service life prediction procedure for chloride induced steel corrosion in reinforced concrete structures is achieved by including a dynamic crack propagation process resulting from corrosion to provide a more realistic prediction on the life of RC bridge structures. The significant phenomena that contribute to the rate and amount of reinforcement corrosion; i.e. heat and moisture transfer, chloride, oxygen transport, are modeled by the two-dimensional time-dependent nonlinear finite difference method. Finite element analysis is adopted to provide fundamental information on how cracks propagate in concrete as the level of corrosion build-up increases. Based on an assumption of uniform distribution of corrosion products, the proposed service life prediction model are capable of predicting the corrosion initiation and propagation process under prescribed initial and boundary conditions.;Through analysis, the variation of the corrosion rate represented by the anodic current density and the amount of reinforcement corrosion with time is obtained within a prescribed environment. Comparison between the proposed cracking model and the conventional non-cracking model indicates that the non-cracking model yields more conservative results and overestimates the service life of structures. The impact of cracks generated from corrosion on service life of corrosion-affected RC structures can not be ignored. Parametric studies indicate that the effect of the material properties of the concrete such as water-cement ratio, cover depth and bar diameter on corrosion rate is significant at the earlier stages before the chloride concentration in contact with the entire steel surface reaches a specified threshold value; while physical factors, such as, the Tafel slopes of the anodic and cathodic reactions, and the oxygen concentration at the outside surface of concrete, have a very significant influence on the corrosion propagation stage. The proposed service life prediction model can serve as a useful tool or guide for engineers, operators, and asset managers in decision making with regard to the serviceability of corroded concrete structures. |
