PDEM-based reliability assessment of RC frames against progressive collapse considering initial local failure

With the increased frequency of progressive collapse events, an accurate and efficient reliability based method for preventing potential structural collapse has become a research focus. Several methods for structural reliability against progressive collapse have recently been proposed; however, they ignore the effect of initial local failure, which may have a significant influence on risk management in protecting structures against progressive collapse. Therefore, this study developed a computation framework for assessing the overall reliability of reinforced concrete (RC) frames against progressive collapse that considers the impact of the initial local failure. The proposed framework quantifies the overall reliability of the structure using the full probability method, which comprises three levels of determination of the initial local failure location, initial local failure assessment, and structural progressive collapse analysis. The efficient probability density evolution method (PDEM) was then employed to calculate the initial local failure probability and structural progressive collapse probability, which are required for achieving a tradeoff between computational efficiency and accuracy. Thereafter, the developed framework was applied to a prototype RC frame, in which the structural resistance was captured using 3-D macro based numerical modeling, which was initially validated by experimental data. Finally, the overall reliability of the RC frame was evaluated according to three different failure criteria, and based on reliability results, various structural strengthening strategies were discussed. Results show that the developed framework can effectively quantify the impact of initial local failure on the reliability of RC frames against progressive collapse. The overall reliability of the structure increases as the input energy decreases. When the input energy greater than or equal to 132 kJ, the overall reliability of the structure investigated is 0.933 for the ultimate damage criterion.