Normalized stiffness degradation C8, C20, C30

A total of 30 full-scale reinforced concrete (RC) columns were tested to develop models for the prediction of the structural behavior of corroded RC columns. Of these, 25 RC columns were tested under cyclic loading for two different applied axial load ratios, namely, 0.20 and 0.40, at three concrete strength levels, namely, 9, 27, and 37 MPa (1305, 3915, and 5365 psi, respectively), and at four corrosion levels. Five RC columns were loaded monotonically with an axial load ratio of 0.20 at four corrosion levels to calculate the damage index. The actual corrosion levels were obtained by breaking the concrete and extracting all the reinforcement bars. The test results demonstrated that the ductility ratios of the corroded RC columns, which were not determined in accordance with energy-based or bilateral failure criteria, could be misleading. The determined energy dissipation capacity and damage index of the columns further revealed the corrosion effects.