Time dependent moment–curvature relationships

Corrosion of reinforcement bars in concrete is directly responsible for serious damage to concrete structures, which may result in premature failure of the structures as a function of time. Therefore, it is necessary to evaluate its damage on the structural performance level. Many models have been developed to predict the corrosion rate of steel in concrete and its effects on structures. It is also possible to evaluate and identify the seismic performance level of reinforced concrete (RC) structures. This study contributes to an understanding of the relationship between these two topics as a function of time to predict the performance level of corroded RC buildings. Three combined parameters (loss of the cross sectional area of reinforcement bars, reduction of the concrete strength, and additional displacement due to slip) as a consequence of corrosion effects were calculated as a function of the corrosion rate for five different time periods (i.e., non-corroded (t: 0), 25, 50, 75, and 100 years). Obtained results were used to perform nonlinear time-history analyses for 20 ground motion records. The results showed that the effect of the corrosion of steel on the seismic performance level is highly significant, and it should be considered carefully in performance analysis.