Predicting Performance Level of Reinforced Concrete Structures Subject to Corrosion as a Function of Time

ABSTRACT: Deterioration due to corrosion becomes a more serious problem when the exact time of expected earthquakes is unknown. Therefore, the prediction of performance levels of corroded reinforced concrete (RC) structures is important to prevent serious premature damage. Many models have been developed regarding the effects of corrosion as a function of time. It is possible to evaluate and identify the performance level of RC structures as immediate occupancy (IO), life safety (LS), collapse prevention (CP), and collapse (C). The first part of this study contributes to an understanding of time dependent effects of corrosion on seismic performance levels of corroded RC buildings that will be a guideline for the further studies for strengthening and assessing of RC buildings. The developed model in the first part of this thesis provide to predict the time dependent seismic performance levels of RC buildings by considering three major effects of corrosion (e.g., deformation due to bond-slip relationships, loss of cross sectional area of reinforcement bars and reduction in concrete compressive strength). In second part of this thesis, the effect of corrosion on the bond strength between reinforcement bars and concrete was studied in a series of experiments. An accelerated corrosion method was used to corrode the reinforcement bars embedded in concrete specimens. Pullout tests were performed to develop an empirical model for the ultimate bond strength by evaluating bond strengths in two different concrete mixes, three concrete cover depths and different mass losses of reinforcement bars after corrosion. Bond-slip relationships for the different corrosion levels were compared for different concrete classes and concrete cover depths. In contrast to developed models found in the literature for the prediction of ultimate bond strength, the newly developed bond strength models in this study provide to predict the bond strength as a function of corrosion level, concrete strength level, crack width and cover-to-diameter (c/D) ratios. It was found that previously developed bond strength models do not represent the actual corrosion behaviour where the bond strength decreases rapidly with increasing corrosion level in those models. Keywords: Corrosion, time-history analysis, performance levels, pullout test, bond strength, bond-slip relationship. ……………………………………………………………………………………………………………………………………………………………………………………………………………………