Abstract

Disproportionate collapse or progressive collapse first attracted the attention of engineers when in 1968, Ronan Point, a 22-storey apartment building in London, collapsed (Ministry of Housing and Local Government, 1968). The events of September 11, 2001 (NIST NCSTAR, 2005), which caused the collapse of the Twin Towers in New York, are another milestone in the research and new design measures to resist progressive collapse of buildings. The incident caused several researchers to focus on the causes of progressive collapse in building structures, seeking the establishment of rational methods for the assessment and enhancement of structural robustness under extreme events. The 9/11 attack also caused increasing enforcement of new design guidance to prevent progressive collapse of different types of structures.