An analytical model on compressive arch action capacity of 3D beam-column sub-assemblages under failure of one or two adjacent interior columns

Abstract Compressive arch action (CAA) is a desired load-bearing mechanism to mitigate the progressive collapse risk of commonly designed reinforced concrete (RC) frames. Thus, there have been number of studies concentrated on the behavior of in-plane beam-column sub-assemblages under a single column removal scenario. However, the effect of possible multicolumn loss scenarios due to severe vehicular impact or terrorist attacks has been neglected in the previous CAA calculation models. This paper develops analytical models to estimate CAA capacity of 3D beam-column sub-assemblages under failure of one or two adjacent interior columns. Due to shortage of relevant data, the proposed formulas are validated through comparisons with the numerical results of a full-scale sub-assemblage. Evaluating the response of sub-assemblages extracted from sample buildings with various frame span lengths, it is shown that the failure of two adjacent interior columns along shorter spans of the floor is more likely to reduce CAA capacity than loss along longer spans. The contributions of the bridging beams over removed columns to arch action capacity are also compared.