Influence of pits characteristics on the failure mode of viaduct in service steel rebars

In the present work, the failure mode of rebars extracted from a reinforced concrete viaduct suffering corrosion in Spain has is studied. It has been confirmed the validity of the strategy based on performing hardness sweeps along a diameter of the bars for determining the mode of failure suffered in service. The same number of rebars extracted from the bridges have failed by plastic collapse or fatigue considering two viaducts suffering corrosion problems. The synergistic effect of corrosion and stress hardening explains how pits location along the bar diameter influences the mode of failure. Large pits close to the longitudinal ribs in the non-parallel ribs side generate a plastic collapse failure according to FEM (Finite Element Modelling) calculations. Fatigue failure is mainly related to the hydrogen concentration associated to pits position. These findings have been obtained from tensile tests between 5.0⁎10 -4 s -1 and 2.4⁎10 -6 s-1 strain rates and fatigue tests between 5 and 30kN. The main contribution of this work is the combination of stress concentration and hydrogen concentration in order to explain tilted fractures (brittle and ductile) in rebars of reinforced concrete bridges in service. • The rebars obtained from a damaged bridge mainly showed pitting at the bar-rib interface. • The location of the pitting is influenced by the corrosion phenomena and stress concentration. • The tilted appearance of the rebar fracture can be explained by shear and hydrostatic stress terms.