Bridges are vital components of transportation infrastructure, and their functionality is crucial for the entire network. If bridges become inoperable, it can cause severe disruption to the transportation system. As reinforced concrete (RC) bridges age, they become more susceptible to environmental stressors such as carbonation and chloride-induced corrosion. Among these stressors, chloride-induced corrosion of the reinforcing steel is particularly significant and widespread, affecting the performance and safety of aging RC bridges. The Swiss Federal Roads Office (FEDRO) initiated research projects to address the corrosion of cantilever walls, which led to the updating of building regulations.

To gain insights into the behaviour of corroded structural elements, the Corroded Tension Chord Model (CTCM) was developed and implemented in ANSYS Mechanical APDL software. This model allows for the evaluation of load-deformation behaviour and load redistribution resulting from localized corrosion. The primary objective of this thesis is to enhance the understanding of the load-bearing and deformational behaviour of reinforced concrete bridges affected by local corrosion.

Two versions of box-girder bridges were designed for this study, one with a edge beam and one without. Two loading conditions were analyzed: one applied the load from load model 1 according to SIA standards, while the other imposed a displacement on a single node. The analysis also explored various combinations of corrosion parameters to comprehensively investigate their effects.

By examining these factors, this research seeks to contribute to the knowledge base surrounding the structural response of corroded bridges. The findings have the potential to inform bridge design, maintenance, and repair strategies, ultimately enhancing the resilience and durability of reinforced concrete bridges in the presence of localized corrosion.

The finite element models utilized in this study provided valuable insights into the localized impacts of corrosion on force distribution around corrosion damage areas. Due to the presence of membrane forces, corrosion pits had a negligible effect on overall load- bearing behaviour. Alternative force paths were observed locally, directing loads towards stiffer regions within the structure, particularly at higher stress levels. However, caution is necessary as the absence of experimental verification of the Corrosion and Corroded Tension Chord Model (CTCM) limits the certainty of the finite element model results in describing real structural behaviour. Therefore, careful consideration and further validation of the CTCM through experimental set-ups are essential.

Exploring supplementary support systems and alternative load paths can provide valuable insights into the effects of corrosion. It is recommended to apply corrosion in regions with lower or absent membrane forces, as these forces may positively influenceii

the overall load-bearing behaviour in the presence of corrosion damage. The modelling of corrosion pit geometry and the sequencing of loading should be carefully considered to accurately simulate structural behaviour. Additionally, the inclusion of time-varyingpitting geometry may further enhance the realism of the model.