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Progressive (Disproportionate) Collapse

Throughout history, there have been many significant structural failures.  While many of these failures have resulted in negative consequences (i.e., death, injury, property loss, etc.), these events present an opportunity to evaluate the validity of engineering design approaches and procedures.  From an engineer's perspective, observation of a structural failure can be as educational as exposure to several years of engineering theory.  In an attempt to improve structural design and prevent structural disasters, engineers continue to refine design guidelines.  Because of these efforts, catastrophic structural failure has become a rare occurrence.  This fact reflects well on the current state of design, as well as the abilities of the engineers that develop and carry out these engineering procedures.

Worldwide, there are several building codes that directly address the type of progressive (disproportionate) collapse (e.g., the United Kingdom Building Regulations, etc.).  While some regulations do a better job of conveying progressive (disproportionate) collapse requirements than others (i.e., by quantifying allowable damage amounts, specifying a design load, etc.), currently there is no explicit engineering design method available pertaining to this potential structural problem.

GSA has improved and supplemented the current progressive (disproportionate) collapse provisions outlined in the GSA and ISC Security Design Criteria.  This effort has consisted of developing an engineering-level analysis and design guideline that provides an engineering-based process that may be applied by both the designer (in the case of new construction) and the analyst (in the case of evaluating a new design or an existing building) for reducing or accessing the potential for progressive (disproportionate) collapse.

See definitions of progressive (disproportionate) collapse.

See examples of progressive (disproportionate) collapse.

See a diagram of a collapse.

See progressive collapse guidelines.
Last Reviewed 3/13/2009