Time-dependent reliability-based redundancy assessment of deteriorated RC structures against progressive collapse considering corrosion effect

redundancy of reinforced concrete (RC) structures, which is generally used to describe the progressive collapse performance, has gained worldwide interests since it is greatly related with the vertical bearing capacity of the structure when subjected to loss of structural components. Especially, in some aggressive environments, the redundancy of RC structures may be an even severer problem since corrosion of reinforcement will cause deterioration of the material properties, thus the progressive collapse potential may get increased. In this paper, we present a quantitative study of the influence of the corrosion effect on the redundancy of the structures. The reliability-based redundancy quantification framework is firstly introduced, in which the static pushdown method is used to represent the progressive collapse behavior of the structure and the probability density evolution method (PDEM) is employed to calculate the reliability index. Then an efficient deterministic finite element modeling strategy is presented in detail, where the fiber element is adopted to model the beam/column components and the macro-level joint model is used to model the bond-slip behavior at the beam-to-column connections. Thirdly, a probabilistic corrosion model is adopted to represent the corrosion effect, which accounts for the variability in both time and space domains. Then the deterioration of concrete properties, rein forcement properties, as well as the bond behavior between these two materials that are induced by the corrosion effect is incorporated into the finite element model. Finally, a case study of RC building subjected to progressive collapse is designed to demonstrate the capacity of the framework and to investigate the time-dependent reliability and redundancy of the structure. Meanwhile, the influences of different corrosion modeling assumptions are also studied.