Best Practices for Reducing the Potential for Progressive Collapse in Buildings NISTIR 7396 [Eng.CiviL]

ABSTRACT

This document is intended to provide owners and practicing engineers with current “best practices” toreduce the likelihood of progressive collapse of buildingsin the event of abnormal loading. The reportincludes a discussion of an acceptable risk approachto progressive collapse, which involves defining thethreat, event control, and structural design to resistpostulated event. Practicalmeans for reducing risk fornew and existing buildings are presented. An extensivereview is provided of the design methods used toenhance a buildings resistance to progressive collapse. These include the indirect method (providingsufficient tie forces), the specific local resistancemethod (designing key elements to withstand abnormalloads), and the alternate load path method (allowing forredistribution of load in the event of the loss of akey member). Design considerations for differentstructural materials are summarized. The methodologyfor evaluating and mitigating progressive collapse potential in existing buildings isalso discussed. Threeappendices provide supporting information. AppendixA presents a worldwide review of progressivecollapse provisions in various national design standards. Appendix B identifies knowledge gaps related toprogressive collapse that require research. Appendix C provides case studies of progressive collapses.This document is not intended to provide step-by-step design guidance for practicing engineers; however,applicable design standards are referenced and summarized in Appendix A.