On the corrosion in reinforced concrete beams: comparative study between different concrete diffusivity prediction models and its effects on the resistance degradation considering the reliability theory

Abstract

Reinforced concrete structures are widely used systems in the world today due to their low relative cost, good structural strength, good fit to imposed shapes and good durability in environments of low environmental aggressiveness. However, as the aggressiveness increases, as in the case of large industrialized cities and/or coastal regions, the durability of these structures may be affected by chemical attack. Among the various chemical agents that attack the concrete structures, chloride ions, via diffusion process inside the concrete, is the main agent of the durability loss, since it starts the reinforcement corrosion. Corrosion is a complex physicochemical process influenced by several parameters that are difficult to control and supervise, which shows the difficulty of modeling. Moreover, several corrosion parameters have great uncertainties inherent to their values, making difficult the realistic representation of the phenomenon. Within this context, there are several models used to quantify and predict this phenomenon. In this context, this project presents the study of reinforcement corrosion and its importance on the durability of reinforced concrete beams, by means of different models of evaluation of the chloride diffusion coefficient within the concrete. These models are compared to each other in a deterministic approach to determine chloride concentrations in concrete, as well as in a probabilistic approach, via Reliability Theory, in the evaluation of the probability of corrosion on reinforced concrete beams. After corrosion has begun, the beams will also be probabilistically evaluated for the deterioration in time of their bending moment and shear strength, also considering the uncertainties in the material parameters. (AU)