History has demonstrated that buildings designed to conventional design codes can lack the robustness necessary to withstand localised damage, partial or even complete collapse. This variable performance has led governmental organisations to seek ways of ensuring all buildings of significant size possess a minimum level of robustness. The research community has responded by advancing understanding of how structures behave when subjected to localised damage. Regulations and design recommendations have been developed to help ensure more consistent resilience in all framed buildings of significant size, and rigorous design approaches have been specified for buildings deemed potentially vulnerable to extreme loading events. This paper summarises some of the more important progressive collapse events, to identify key attributes that lead to vulnerability to collapse. Current procedures and guidelines for ensuring a minimum level of performance are reviewed and modelling methods for structures subjected to localised damage are described. These include increasingly sophisticated progressive collapse analysis procedures, including linear static and non-linear static analysis, as well as non-linear static pushover and linear dynamic methods. Finally, fully non-linear dynamic methods are considered. Building connections potentially represent the most vulnerable structural elements in steel-framed buildings; their failure can lead to progressive collapses. Steel connections also present difficulties with respect to frame modelling and this paper highlights benefits and drawbacks of some modelling procedures with respect to their treatment of connections.

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Breakage of glazing is the largest source of injury from an explosion in an urban area, whether the explosion is due to military attack, terrorist attack, accidental explosion or a natural disaster such as the meteorite over Cheylabinsk, Russia on 15 February 2013. The reasons for this are the ubiquity of glazing in the modern built environment and its proximity to people, its brittleness and low fracture energy, and the formation of elongated and sharp-edged glass fragments. To minimise the injury hazard it is desirable to be able to assess the response. This briefing note explains the response of glazing and glazing systems to blast waves from an external explosion. By choice of suitable makeup of a glazing system, the hazard level to building occupants from a given level of blast loading can be reduced to acceptable levels.