Influence of a triaxial stress state on the load-deformation behaviour of axisymmetrically corroded reinforcing bars.

[Display omitted] • Triaxial stress state occurs pronouncedly for short pit lengths at corroded rebars. • Apparent uniaxial peak stress increases up to 35% for axisymmetric damage. • Ductility of pit region is higher than predicted by strain localisation models. • Yield behaviour of steel at corrosion pit is significantly altered. • Pit geometry strongly influences intensity of triaxial stresses. Local corrosion damage reduces the load-bearing capacity of reinforcing bars and, even more severely, their deformation capacity. These effects are mainly attributed to the reduced cross-sectional area and the accompanying strain localisation. However, several experimental studies found an altered load-deformation behaviour of naturally corroded as well as artificially damaged reinforcing bars, including an apparently increased tensile strength, which cannot be explained solely by strain localisation. Accordingly, in an experimental campaign carried out by the authors on locally axisymmetrically damaged reinforcing bars, the observed peak load increased with decreasing damage length, and the deformation capacity was much less impaired than predicted by established strain localisation models. A series of nonlinear FE analyses was carried out to investigate a potential effect of the local stress state in the vicinity of the local corrosion damage. The results indeed revealed a triaxial stress state in this region, caused by the local deviation of the stress trajectories, explaining the experimental observations on a mechanical basis, and indicating a pronounced influence of the triaxial stresses on the uniaxial stress–strain behaviour of the bar in the vicinity of the corrosion pit. A parametric study was conducted to investigate a broader range of corrosion damage geometries and the corresponding triaxial stresses. The results indicate that the transverse stresses strongly affect the apparent uniaxial mechanical steel properties (yield stress, tensile strength, deformation capacity, loss of yield plateau) for short damage lengths typically found for pitting corrosion. A simplified modelling approach is proposed to capture the governing effects on the apparent uniaxial stress–strain curve of locally corroded reinforcing bars. [ABSTRACT FROM AUTHOR]