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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
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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