Failure Probability of Damaged RC Frame under Fire Using Markov Chain.

Engineering structures are subjected to different loads during their lifetime, which may cause damage or secondary loading effects. Among loading effects on structures, explosion and earthquake may also cause fire. A damaged structure can experience a different response under fire loading in comparison to the intact structure. In addition to strength loss, damaged reinforced concrete (RC) frames may be exposed to cracking and spalling of concrete cover at various damage levels. These phenomena affect heat transfer in the structural section. In this study, Markov probability chain analysis is used to determine the probability of the occurrence of first failure in a 7-story RC frame damaged at different levels is evaluated under fire loading. The time of the first failure in structural elements is also calculated and presented for each damage level. The results show that increased damage levels in RC frame results in a greater probability of failure and reduced time of failure under fire loading scenario. The failure probability was found as zero at damage indices of 0, 0.1 and 0.2, with non-zero probabilities for greater damage indices. The framework developed in this paper outlines the performance assessment procedure for a damaged structure that is later exposed to fire loading.