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ASCE 7 wind speeds

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Dave,

I downloaded the data files that were referenced in that paper to see what 
was used for the Tucson area to develop the ASCE wind chart.  I don't have 
the data at hand, but IIRC, Tucson was part of two different sets of 
superstations.  Actual data for Tucson came from two sources, the USWB, which 
is located at the Tucson International Airport, and Davis-Monthan AFB, which 
is about 3 miles from TIA.  Although weather data have been collected in 
Tucson since the late 1800's, and the USWB is one of the 128 U.S. weather 
stations, only 30 years of wind records were included in the USWB data, and 
about 40 years of wind records were included in the Davis-Monthan AFB wind 
records.  Even in the 30 year record, there were several gusts in the 80-90 
mph range, which should probably give Tucson a 100 mph 3-second gust with a 
50-year return interval instead of the 90 mph in ASCE 7.  This would 
represent about a 20 percent increase in wind force.

If nothing else, I think that the claim that the research had not been 
published, nor available for critical review before it was adopted by ASCE 
makes the values suspect.  I think that this alone is sufficient to have the 
research conducted again.

Since in previous editions of ASCE 7, the gust factors applied to the 
fastest-mile wind speeds were in the .2 to .3 range, and the fastest-mile 
wind speed for Tucson was 75 mph, I am using a design wind gust of 100 mph in 
my designs.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Dave Evans wrote:

. > A paper in the April 2003 issue of the ASCE J. of Structural Engineering 
. > concludes that the current ASCE 7 wind map significantly 
. > overestimates wind loads in some areas of the US and underestimates 
. > it in others.  Does anyone know if the map is going to be revised and, if 
. > so, who is in charge of the revision process?  I'm interested in any 
. > possible changes in the map for the northeast corner of Maine.

. > Thanks,
. > David Evans, P.E.
. > TNH, Inc.

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