ABSTRACT
Condition assessment of existing reinforced concrete (RC) structures has been a major issue. Nevertheless, analysis of existing structures requires a distinct approach as compared to design of new ones, with particular emphasis on the selection of the target reliability index. When comparing reliability levels of new RC structures and existing ones, it must be considered that the analysis corresponds to two different times. In the design of new structures, there is an unaccounted extra safety margin due to concrete strength gain with age. The research presented herein evaluates the reliability of existing RC columns based on the same time reference. To this end, an equivalent 28-day concrete strength is obtained from the one associated to the existing structure. Probabilities of failure are computed by Monte Carlo simulation and the effects of different parameters are investigated. The results indicate that the effect of concrete gain with age should not be overlooked.
