Saturday, September 12, 2009

Wind Exposure Category ...

... here are the `Exposure Categories' for wind design from the 2003 IBC. You will need these for your homework problem. My intent here is educational (not that you use these instead of `buying' your own). Before you start designing in real life (IRL) you will want to get a current copy of the applicable code for your project ... and/or ... a current copy of ASCE-7.

Enjoy ... (And let me know if there are typos.)

Borrowed from … 2003 IBC

1609.4 …


Exposure B. Urban and suburban areas, wooded areas or other terrain with numerous closely spaced obstructions having the size of single-family dwellings or larger. Exposure B shall be assumed unless the site meets the definition of another type …

Exposure C. Open terrain with scattered obstructions, including surface undulations or other irregularities, having heights generally less than 30 ft … This exposure shall also apply to any building located within Exposure B-type terrain where the building is directly adjacent to open areas of Exposure C-type terrain in any quadrant for a distance of more than 600 ft. This category includes flat open country, grasslands and shorelines in hurricane-prone regions.

Exposure D. Flat, unobstructed areas exposed to wind flowing over open water for a distance of at least 1 mile … inland waterways, the Great Lakes and coastal areas of California, Oregon, Washington and Alaska. This exposure shall apply only to those buildings and other structures exposed to the wind coming from over the water … extends inland 1500 ft or 10 times the height of the building or structure, whichever is greater.

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