An evaluation method for progressive collapse resistance based on a collapse probability and a resistance reservation indexes

The existing evaluation indexes for the structural progressive collapse resistance are related to the specific initial local failure in a structural system, which cannot be effectively used to assess the progressive collapse-resisting performance of the structure. A collapse probability index and a resistance reservation index were proposed based on the analysis of structural systems under all typical initial local failures to comprehensively assess the progressive collapse resistance of overall structural systems. A simplified method to evaluate the progressive collapse resistance for the practical engineering was also suggested to feasibly calculate the two indexes. The numerical examples show that the collapse probability index decreases and the resistance reservation index increases with the improvement of seismic fortification intensity and the enhancement of slabs. The numerical results are consistent with the results of theoretical analysis, indicating the progressive collapse resistance of structures can be quantitatively assessed by the two proposed indexes. The simplified method can feasibly measure these two indexes to meet the requirement of engineering design and optimization.