Basic Wind Speed Conversion Using Uniform Building Code


From UBC 97, under SECTION 1616 – DEFINITIONS:

BASIC WIND SPEED is the fastest-mile wind speed associated with an annual probability of 0.02 measured at a point 33 feet (10 000 mm) above the ground for an area having exposure category C.

From SBC 301, under SECTION 6.2 – DEFINITIONS

Basic Wind Speed, V. 3-second gust speed at 10 m above the ground in Exposure C (see Section 6.4.2) as determined in accordance with Section 6.4.1.

FIGURE 6.4-1
BASIC 3-SECOND GUST WIND SPEED IN km/h FOR SELECTED CITIES OF SAUDI ARABIA.
ADOPTED FROM SAUDI ARAMCO DATA SAES A-112.

From [ 2007 California Building Code‚ Title 24‚ Part 2 (First Printing)‚ Includes Supplements through Jan 11 ] –  SECTION 1609 WIND LOADS  – 1609.3 Basic wind speed.

1609.3.1 Wind speed conversion.

When required, the 3-second gust basic wind speeds of Figure 1609 shall be converted to fastest-mile wind speeds, Vfm, using Table 1609.3.1 or Equation 16-34.

( Equation 16-34)

where: V3S = 3-second gust basic wind speed from Figure 1609.

TABLE 1609.3.1 EQUIVALENT BASIC WIND SPEEDS a, b, c

For SI: 1 mile per hour = 0.44 m/s.

a. Linear interpolation is permitted.
b. V 3S is the 3-second gust wind speed (mph).
c. Vfm is the fastest mile wind speed (mph).


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