Disproportionate Collapse Design Considerations — A Comprehensive Approach

Abstract

Recent efforts to develop progressive collapse guidelines in the United States reveal an interest in improving design requirements to address disproportionate collapse, especially in the context of blast-resistant design. As a result, several ongoing research projects are investigating structural response under disproportionate collapse conditions. Generally, disproportionate collapse considers the complete loss of a critical load-carrying element - typically a column - that leads to a disproportionate collapse of other parts of the structure. However, simply considering disproportionate collapse through a complete member removal, as is typical per current design procedures, does not account for disproportionate failures that may occur due to localized effects. Engineers need to consider all possible failure mechanisms in design, including disproportionate collapse, for a more accurate determination of the initiation of a global failure. Inspired by such tragedies as the Hyatt Regency walkway collapse where the localized connection failure led to the disproportionate collapse of two entire walkways, this study examines expanding the definition of disproportionate collapse to consider local failures and their effect on members or systems. By characterizing the response and behavior of a structural member after localized failure occurs, appropriate design considerations can be developed. Results from this study will highlight the localized effects on the structural capacity considering disproportionate collapse and show why these types of failures must be considered by design professionals, code developers, and research efforts.