Development of a threat-oriented, risk-based analysis & design approach for blast protection of window glazing building envelope systems in downtown centres

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With the introduction of the new Canadian Standards CSA S850-12 - Design And Assessment of Buildings Subjected to Blast Loads, Entuitive is tasked with evaluating the vulnerability of existing glazing systems, which comprise a large portion of the building envelope systems within high rise buildings in downtown centers in Canada. Evidence from past incidents, including the bombings of Manchester UK in 1996 and Oklahoma City in 1995, shows that a large number of injuries often results from extensive damage to building envelope components including glass facades, which may occur at considerable distance from the detonation site. To address this problem, a number of standards for the blast protection of buildings (e.g. CSA S850-12 and ASCE 59-11) and safety criteria (e.g. ISC 2001) were put forth in the past two decades, in addition to software for the design and analysis of window glazing subjected to blast loads (e.g. USACE 2012). However, currently implemented measures for blast performance enhancement and rehabilitation (hardening) of buildings' glazing facades vary considerably. These hardening measures may involve the use of a wide range of strategies individually or in combinations, including: fragment retention films, laminated glass, blast curtains, catching systems (e.g. catch cable/bar retrofit and energy-absorbing systems), mesh screens, and secondary window systems. However, no guidelines are made available in the current North American standards (CSA S850-12 and ASCE 59-11) regarding the building envelope performance indicator necessary to