A corrosion model for the interpretation of cyclic behavior of reinforced concrete sections

A generalized cyclic steel model characterized by isotropic and kinematic hardening, inelastic buckling in compression and corrosion of rebars in reinforced concrete (RC) structures is presented. This model has been implemented in in-house fiber code CYRUS-M developed in MATLAB, to perform seismic analysis of RC sections. The model is particularly accurate with respect to experimental cyclic behavior of rebars with buckling in compression when the strain does not exceed 1.5 %. 12 configurations of RC cross-sections were selected as case studies for 3 geometries and different steel configurations, assumed representative of RC columns or bridge piers (in a suitable scale). Each section was subjected to two groups of cyclic curvature histories representative of severe seismic loads, not far from collapse. Different axial loads and corrosion percentages (no corrosion, moderate or high) have been selected to perform cyclic parametric analyses. The results of the comparison among RC sections with uncorroded and corroded rebars have been discussed. Numerical results show that the maximum compressive strain is always smaller than 1.5 %, therefore the proposed steel model is a valid tool for structural assessment. Corrosion reduces the section capacity in terms of strength and energy dissipation and hysteretic damping.