Storm & Security

SPecIAL/REPORT Tackling Tornadoes Success of hurricane impact standards spur interests in window standard for tornadoes In late February, a tornado out- break spread across areas of the South and Midwest, leaving 13 people dead in Kansas, Missouri, Illinois and Ten- nessee. In some areas, almost nothing was spared; 200 homes and more than 25 businesses were damaged in the small town of Harrisburg, IL. Then, just 48 hours later, another line of storms that stretched from Mississippi to the Ohio River Valley produced 159 reported tornadoes, resulting in 37 fatalities. March and April also have had their share of devastating storms. One hundred twenty-four tornadoes touched down across the country in March. And in early April, a tornado out- break spread across a portion of the Dallas-Fort Worth, TX, area damaging more than 1,000 homes and leaving nearly 350 of them completely destroyed. Due to the increasing frequency of severe weather events, interest has grown in tornado-mitigating fenestration products, says Greg McKenna (Kawneer Co., Inc.), member of American Architectural Manufacturers Association's (AAMA) Tornado Hazard Mitigation Task Group. Dennis Kelly (Graham Architec- tural Products), also a member of AAMA's Tornado Hazard Mitigation Task Group, believes there has been a keener awareness of protecting inhabitants since the publication of hurricane impact standards, which have been proven successful, as well as blast mitigation standards. Adequate protective construc- tion standards do exist, notably as Federal Emergency Management Agency (FEMA) 361 (2008), Design and Construction Guidance for Community Saferooms, and the inter- related International Code Council (ICC) 500-08, Standard for the Design and Construction of Storm Shelters. While these standards specifically address designated storm shelters, many experts recommend that "essential" (International Building Code Occupancy Category IV) facili- 14 ties, such as hospitals, fire/rescue stations, etc., should be built to these storm shelter standards. While a windowless concrete bunker likely would stand up well, the architect's challenge is to include storm protection without eliminating glass or other cladding that enhances the building's aesthetics. FEMA 361 and ICC 500 allow for windows, so long as they are tested for structural integrity and debris impact at tornadic wind speeds and are shielded by louvers or other protective devices. However, these require- ments do not address all window performance aspects for a functional building. In response to the challenge, and in keeping with ongoing AAMA collaboration with National Institute of Building Sciences' Building Enclosure Technology and Environmental Council (BETEC) to develop security-related fenestration test methods and standards, AAMA has published AAMA 512-11, Voluntary Specifications for Tornado Hazard Mitigating Fenes- tration Products. | by Dean Lewis | A windowless bunker would stand up well, but not fit all occupant needs. With tornado incidents on the rise, a new generation of heavy commercial windows and doors offers a higher degree of protection from wind damage. STORM&SecURITy PROTecTION / 2012 FORECAST

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