Basic wind speed

Specified basic wind speed and relevant site data. 

In the latitudes occupied by the US the climate is dominated by westerly winds. The basic wind speed may be adjusted to ensure that the risk of it being exceeded is the same for all directions. This is achieved by the wind speed factor Sa. 

Basic wind speed (mph) Wind design pressure (Ib/ft )... 

For a comparison, for category C (open flat terrain areas) the allowable design wind pressure is 29.7 Ib/fF at basic wind speed of 100 mph. 

T = period of vibration, sec V = basic wind speed from map. Figure 3-1, mph... 

V,ef = basic wind speed converted to ft/sec Vz = mean hourly wind speed at hei t z, ft/sec z = equivalent height of vessel, ft = minimum design height, ft, from Table 3-3... 

Figure 3-1. Basic wind speed (Reprinted by permission from ASCE 7-95 Minimum Design Loads for Buildings and Other Structures, published by...

The basic wind speed on the map. Figure 3-1, corresponds to a 3-sec. gust speed at 33 ft above the ground, in Exposure Category C with an annual probability of 0.02 (50-year mean recurrence interval). 

Exposure D represents the most severe exposure in areas with basic wind speeds of 80 mph or greater, and terrain, which is flat, unobstructed and faces large bodies of water over one mile or more in width relative to any quadrant of the building site. Exposure D extends inland from the shoreline 4 lids or 10 times the building height, whichever is greater. 

Figure 3-6. Basic wind speed map of the U.S. minimum basic wind speeds in miles per hour (x 1.61 for Km/h). (Reproduced from the 1997 edition of the "Uniform Building Code, copyright 1997, with permission of the publisher, the International Conference of Building Officials.)...

V = basic wind speed, mph Vc = critical wind velocity, mph Vj,j,Vc2 = critical wind speeds for modes 1 and 2, mph or fps... 

Figure 4-1 a. Basic Wind Speeds for Occupancy Category I Buildings and Other Stnjctures. With permission from ASCE. 

BASIC WIND SPEEDS IN MILES PER HOUR from (he UNIFORM BUILDING CODE... 

In addition, it is necessary to modify Eq.a by the force coefficient Cj, which is 0.6 for a cylinder, and by the gust factor Gj for the height of the vessel above ground level. Once the basic wind speed is determined from Fig. 16.3, the velocity pressure for a cylinder is obtained from Table 16. la. To determine the... 

Height Above (iround (ft) Basic Wind Speed (mph) from Fig. 16.3 ... 

Setting/i = fundamental natural frequency of the tower (ASCE 7-2005 [2] uses i), V = basic wind speed, mph (m/s), in which 80 < V< 140mph (some note as Vret)-... 

Wind force coefficient, Cf = 0.7 Basic wind speed, V = 85mph Importance factor, 1 = 1 Exposure category = C Wind Directionality Factor, Q = 0.95 Topographic Factor, K, = 1.00... 

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