Probability-based progressive collapse-resistant assessment for reinforced concrete frame structures

Abstract

Progressive collapse is a form of disproportionate damage, which is induced by an initial local failure that propagates throughout a large portion or the entirety of structural systems. The initial local failure may occur anywhere in a structural system, which consequently exhibits different collapse behaviors. However, the progressive collapse resistance is an inherent property of the entire structural system regardless of any specific initial local failure. This article proposes a collapse probability index to assess the progressive collapse resistance of reinforced concrete frame structures. Such an index is capable of measuring all typical initial local failures instead of any specific ones. The collapse fragility curve is further established based on the collapse probability index, which varies with an increase in the nominal gravity. The structural redundant resistance to progressive collapse can be assessed by the fragility curve. Furthermore, a simplified assessment method is proposed to measure the collapse probability indices feasibly of reinforced concrete frames under different nominal gravity levels. The proposed method based on the collapse probability index can comprehensively evaluate the progressive collapse resistance of reinforced concrete frames which is validated through analysis of a single four-story and a group of eight-story reinforced concrete frame structures.