Best practices for reducing the potential for progressive collapse in buildings

Abstract

This document is intended to provide owners and practicing engineers with current "best practices" to reduce the likelihood of progressive collapse of buildings in the event of abnormal loading. The report includes a discussion of an acceptable risk approach to progressive collapse, which involves defining the threat, event control, and structural design to resist postulated event. Practical means for reducing risk for new and existing buildings are presented. An extensive review is provided of the design methods used to enhance a buildings resistance to progressive collapse. These include the indirect method (providing sufficient tie forces), the specific local resistance method (designing key elements to withstand abnormal loads), and the alternate load path method (allowing for redistribution of load in the event of the loss of a key member). Design considerations for different structural materials are summarized. The methodology for evaluating and mitigating progressive collapse potential in existing buildings is also discussed. Three appendices provide supporting information. Appendix A presents a worldwide review of progressive collapse provisions in various national design standards. Appendix B identifies knowledge gaps related to progressive 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.

Material modelling of tensile steel component under impulsive loading

“…The dependency on the strain rate of the bolts' material is accounted considering literature reports: impact tests on A 325 bolts recovered from the WTC debris showed very low sensitivity to strain rate [9], showing that high strength steels are less sensible to the effects of strain rate variation. According to Chang and his co-authors [10], a dynamic increase factor (DIF) of 1.1 may be considered for the bolts.…”

Reassessing the Plastic Hinge Model for Energy Dissipation of Axially Loaded Columns

“…Ever since the collapse of the 110 storey twin towers in New York, USA, the research efforts have intensified on the topics such as progressive collapse of buildings [1,2], blast resistant design of buildings [3,4] and energy dissipation of structures [5,6]. Some studies exist on the topic of energy dissipation of structural members, however, they are generally confined to the automotive industry whose aim is to improve crash worthiness of their manufactured vehicles.…”

Disproportionate collapse analysis of cable-stayed steel roofs for cable loss

“…Although disproportionate collapse has been an area of significant research lately (Ellingwood et al, 2007;Starossek, 2007;Structures Congress SEI, 2009), most efforts have focused on the effects of the phenomenon on buildings (Tomasetti et al, 2005;Byfield et al, 2007;Demonceau and Jaspart, 2008;Izzuddin et al, 2008;Gerasimidis et al, 2009;Kim and Kim, 2009;Knoll and Vogel, 2009;Dubina et al, 2010) rather than roofs or bridges. It is not surprising that most of the guidelines produced so far (GSA, 2003;DoD, 2009) include mainly criteria and requirements for building structures.…”