Influence of corrosion on nonlinear tension stiffening of concrete under monotonic and cyclic loading

Reinforced concrete (RC) structures are highly susceptible to reinforcement corrosion, which leads to a significant reduction in their structural capacity. Corrosion particularly affects the bond between concrete and steel reinforcement in RC members, affecting the tensile capacity of the uncracked concrete between cracks—a phenomenon known as tension stiffening. Existing research on tension stiffening behaviour in corroded RC members has primarily focused on low corrosion levels under monotonic loading, leaving gaps in understanding its behaviour at higher corrosion levels or under cyclic loading. This study addresses these gaps by experimentally investigating the effects of corrosion on the nonlinear tension stiffening behaviour of RC members under both monotonic and cyclic loading, across a range of corrosion levels. A total of 28 RC specimens, including uncorroded and artificially corroded specimens, were tested under uniaxial tension. Crack formation and propagation were monitored using Digital Image Correlation (DIC). The results demonstrate that corrosion significantly reduces the tension stiffening of concrete, with larger steel bar sizes exacerbating this effect. Furthermore, current models are insufficient in prediction of crack spacing and width of corroded structural elements, which highlight the need for more robust and reliable models.