Systematic Reliability-Based Approach to Progressive Collapse

Abstract

Recent structural failures in buildings, occurring in a progressive way, have raised awareness of the profession toward the need for robustness in structural design. However, systematic approaches for robust design, considering inherent design uncertainties, are still scarce. This paper proposes a systematic reliability-based approach to the analysis of progressive collapse, with a main goal of identifying key elements in a redundant structure. The approach involves a threat-specific analysis, in which initial damage probabilities are evaluated for a given loading event. Damage propagation and ultimate collapse are also investigated and used to rank elements in a system in terms of their vulnerability regarding structural collapse. The key element is identified as the one presenting the largest intersection between vulnerability and importance with respect to collapse. Identification of key elements can help to guide and simplify the design process. The formal procedure proposed herein should also be useful for automatically guiding design optimization software, having robustness as a design goal.