ASCE 7 Basic Wind Speed

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Per definition by ASCE 7-22, ASCE 7-16 & ASCE 7-10, Section 26.2 is defined as:


BASIC WIND SPEED (V): Three-second gust speed at 33ft above the ground in Exposure C (see Exposure Categories) as determined in accordance with ASCE-7  Section 26.5.1.

The wind shall be assumed to come from any horizontal direction. The basic wind speed shall be increased where records or experience indicate that the wind speeds are higher than those reflected [in ASCE 7-22/16 Section 26.5.1].

Basic wind speed is typically reported in ultimate load (Vult).  This is a factored value that is reduced by the formula Vasd=Vult* sqrt(0.6).  Vasd is the allowable design wind speed. [both though represent a 3-second gust; it’s just how the number is presented].

Important to note that there are different values for sustained vs. 3-second gust winds vs. sustained one-minute fastest mile.  When you hear a weather report stating ‘gusts up to XXmph’, that’s typically the 3-second value vs the sustained winds reported.  Sustained wind velocities are the average wind speed over a period of one minute. Sustained wind speeds are what are used to classify hurricanes & for the  Saffrir-Simpson Hurricane Wind Scale.  Gusts would be higher than these velocities.

Wind speed is not wind pressure.
There are many wind pressures that could develop from a single wind speed.  Click here to learn more.

Here’s a helpful video found (by others) to explain the difference between basic wind speed & wind gust.

Last Update: February 15, 2024  

March 12, 2021  Codes & Standards  
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