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Wind Loads-UBC vs. ASCE

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ASCE 7-98 wind map shows maximum "3 sec. gust wind
speed" of 150 mph, whereas according to UBC 97, the
maximum "Basic Wind Speed" is limited to 130 mph. Is
there any correlation between the two terms? If not,
is there any formula for extrapolating wind stagnation
pressure for basic wind speed in excess of 130 mph,
while using UBC 97?

2. ASCE 7-88 showed the gust factors, gz, as a
function of the height 'z' along the height of the
structure.  However, ASCE 7-98 gives a single value
for gz (Sec. 6.5.8). Quick calculation indicates that
the force due to wind would be less, if calculated
with 7-98 provisions. The reduction is not
insignificant. Were the provisions of 7-88 overly
conservative or is there something in error in 7-98?

Rajendran

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