Effect of corrosion on cyclic behaviour and damage progression of reinforced concrete beams

This study investigates the cyclic performance of reinforced concrete (RC) beams with different grades of reinforcement (Fe 500D, Fe 550D, and Fe 550 SD) and subjected to varying levels of corrosion. Beams with 0%, 15%, and 30% target corrosion, primarily affecting the bottom longitudinal reinforcement and stirrups, are tested under reversed cyclic loading. Digital Image Correlation (DIC) is employed to capture strain localisation and damage evolution, while 3D scanning is used to characterise corrosion morphology and quantify residual cross-sectional area loss of the reinforcement. The non-corroded specimens exhibit stable ductile flexural behaviour, whereas corroded beams develop pronounced directional asymmetry and brittle flexural–tension failure governed by premature fracture of the bottom longitudinal bars at locations of severe pitting near the fixed end. Severe stirrup deterioration may have contributed to the reduced post-yield deformation capacity through loss of lateral restraint and its possible interaction with the fracture of severely pitted longitudinal bars. Corrosion markedly increases stiffness degradation and reduces cumulative energy dissipation, indicating a pronounced loss of ductility and cyclic performance even at moderate corrosion levels. The corrosion indicators show stronger associations with deformation-related response parameters than with strength parameters. A numerical simulation has also been performed to support the experimental findings and provide complementary insight into the observed cyclic response.