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Explore the impact physics of large and small missiles like timbers, roof tiles, and glass particles near ground level. Learn about debris analysis standards and provisions in building codes, including ASTM E1886-02 and ASCE7-02. Discover glazing and shutter system designs meeting impact standards and product approvals from authorities like Dade County and ICC. Dive into the risk model associated with windborne debris.
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THE BUILDING ENVELOPE: Lecture 6 Analysis of Debris Loads
DEBRIS LOADS: PHYSICS Large Missiles: Timbers, roof tiles, sheet metal, bricks Fly or tumble near ground Impact speed 1/3 to 1/2 of V Small Missiles: Roof gravel, glass particles, Fly at rooftop elevations Impact speed 90% of V
ASTM STANDARD E1886-02(TEST METHOD) • Large missile: 4.5 - 15 lb 2x4 timber impacting between 0.10 and 0.55 of the basic wind speed (3-sec gust) • Small missile: solid steel ball having a mass of 2 gm impacting between 0.40 and 0.75 of the basic wind speed (3-sec gust)
DEBRIS IMPACT PROVISIONSIN ASCE 7-02 • Hurricane prone regions • Wind borne debris regions • Glazing, impact resistant • Impact resistant covering
IMPACT TEST PROTOCOL • Impact with representative missile • large missile (2x4 timber) • small missile (2 gm steel ball or rock) • Apply fluctuating pressures • inward acting • outward acting
U.S. CODES AND STANDARDS WITH DEBRIS IMPACT PROVISIONS • ASCE 7-02 • International Building Code • International Residential Code • Florida Building Code • TWIA Building Code • ASTM E1886/1996
GLAZED OPENING DESIGNS FOR WINDBORNE DEBRIS
PRODUCT APPROVALS • Dade County (Florida) Office of Code Compliance • Texas Department of Insurance • ICC Product Evaluations