The Structural Behaviour of Corroded Reinforced Concrete Beams: Experimental and Numerical Studies for the Assessment of Corrosion-damaged Reinforced Concrete Beams

Assessing the structural performance of reinforced concrete (RC) structures damaged by chloride-induced corrosion is an important research topic with a high societal impact. Different models exist in the literature to predict the flexural capacity of corroded RC beams. These models incorporate corrosion damage according to damage relations calibrated on a specific set of data. The variety of approaches and relations in incorporating pitting corrosion and bond deterioration makes it challenging to extend these models for the assessment of corrosion-damaged structures. Therefore, the thesis investigates a modelling approach, which incorporates corrosion damage without the need for calibrated damage relations.

To achieve the goal of the thesis, a fundamental understanding of the relation between the different types of corrosion damage (rebar cross-section loss, corrosion cracks, and interface damage) and their influence on the flexural capacity is studied. Accelerated corrosion experiments are performed to study the relation between the longitudinal and transverse corrosion cracks as well as the layout of the reinforcement on the development of the cross-section loss and pits in the rebar. Then, bending tests are performed to study the influence of pitting corrosion and bond deterioration on flexural behaviour; mainly the development of flexural cracks and the flexural capacity.

Two types of models are developed in the thesis. A 2D RC tension bar model and a 2D numerical model of beams were developed based on the beams of the experimental tests. The RC tension bar model aims to study methods to modify the interface stiffness to simulate developed cracking patterns. It also studies the reduction of the bending capacity as a function of the average and local cross-section losses of the rebar. The developed methods incorporate corrosion damage without the need for empirically calibrated damage relations. The 2D beam models incorporate the interface stiffness in addition to the pitting corrosion to simulate the reduction in the flexural capacity. The validity of the predictions is investigated by comparing the numerical results to the experimental ones.

As an application, the developed modelling approach is extended to assess the residual capacity based on corrosion crack width measurements. Three relations between the crack width and the corrosion level are studied. They were calibrated on samples with one rebar, two rebars, or calibrated on an extensive dataset. The latter relation includes parameters such as the rebar diameter, cover depth, and concrete material properties. The reliability of the prediction of each type of relation is assessed by deriving partial safety factors of the modelling error.