-*»acteristics, shall be designed using recognized literature Documenting such wind load effects or shall use the wind tunnel
•ocedure specified in Section 6.6.
<L5,2.1 Shielding. There shall be no reductions in velocity pres-iar- due to apparent shielding afforded by buildings and other aractures or terrain features.
<kSJ,2 Air Permeable Cladding. Design wind loads deter-
——ed from Section 6.5 shall be used for air permeable cladding '•less approved test data or recognized literature demonstrate h—cr loads for the type of air permeable cladding being
-awdered.
AJ-J Design Procedure.
; The basic wind speed V and wind directionality factor K^ shall be determined in accordance with Section 6.5.4.
1 An importance factor I shall be determined in accordance »ith Section 6.5.5.
: An exposure category or exposure categories and velocity pressure exposure coefficient K^ or K/,, as applicable, shall be determined for each wind direction in accordance with Section 6.5.6.
•'• A topographic factor Kz, shall be determined in accordance with Section 6.5.7.
; A siist effect factor G or G f, as applicable, shall be deter-auned in accordance with Section 6.5.8.
i- An enclosure classification shall be determined in accordance with Section 6.5.9.
'ilernal pressure coefficient GCp, shall be determined in A^-ordance with Section 6.5.11.1.
» Lcermil pressure coefficients Cp or GCp/, or force coeffi-"-/nis Cf, as applicable, shall be determined in accordance »iih Section 6.5.11.2 or 6.5.11.3, respectively.
* Velocity pressure qz or qh, as applicable, shall be deter-•mned in accordance with Section 6.5.10.
i Design wind load p or F shall be determined in accor-tece with Sections 6.5.12, 6.5.13, 6.5.14, and 6.5.15, as ^piicable.
'•lit* 1—c Wind Speed. The basic wind speed, V, used in ik —enination of design wind loads on buildings and other
———b shall be as given in Fig. 6-1 except as provided in W—— 6-5.4.1 and 6.5.4.2. The wind shall be assumed to come ii— — horizontal direction.
i«fc*J Special Wind Regions. The basic wind speed shall be in-
——— ••ere records or experience indicate that the wind speeds
•Rilllkr dun those reflected in Fig. 6-1. Mountainous terrain, JfLJnd special regions shown in Fig. 6-1 shall be examined for
———I »«»d conditions. The authority having jurisdiction shall,
ii! '--.aBary adjust the values given in Fig. 6-1 to account for .wwms suai »ind speeds. Such adjustment shall be based on meal information and an estimate of the basic wind speed
• accordance with the provisions of Section 6.5.4.2.
—•ation of Basic Wind Speeds from Regional
Dta. In areas outside hurricane-prone regions, re-
-:ic data shall only be used in lieu of the basic ^ a\ en in Fig. 6-1 when (1) approved extreme-value
•lysis procedures have been employed in reducing I (2) the length of record, sampling error, averaging er height, data quality, and terrain exposure of

the anemometer have been taken into account. Reduction in basic | wind speed below that of Fig. 6-1 shall be permitted.           |
In hurricane-prone regions, wind speeds derived from simulation techniques shall only be used in lieu of the basic wind speeds given in Fig. 6-1 when (1) approved simulation and extreme value statistical analysis procedures are used (the use of regional wind speed data obtained from anemometers is not permitted to define the hurricane wind-speed risk along the Gulf and Atlantic coasts, the Caribbean, or Hawaii) and (2) the design wind speeds resulting from the study shall not be less than the resulting 500-year return period wind speed divided by \/1.5.
In areas outside hurricane-prone regions, when the basic wind speed is estimated from regional climatic data, the basic wind speed shall be not less than the wind speed associated with an annual probability of 0.02 (50-year mean recurrence interval), and the estimate shall be adjusted for equivalence to a 3-s gust wind speed at 33 ft (10 m) above ground in exposure Category C. The data analysis shall be performed in accordance with this chapter.
6.5.4.3 Limitation. Tornadoes have not been considered in developing the basic wind-speed distributions.
6.5.4.4 Wind Directionality Factor. The wind directionality factor, K^, shall be determined from Table 6-4. This factor shall only be applied when used in conjunction with load combinations specified in Sections 2.3 and 2.4.
6.5.5 Importance Factor. An importance factor, 7, for the building or other structure shall be determined from Table 6-1 based on building and structure categories listed in Table 1-1.
6.5.6 Exposure. For each wind direction considered, the upwind exposure category shall be based on ground surface roughness that is determined from natural topography, vegetation, and constructed facilities.
6.5.6.1 Wind Directions and Sectors. For each selected wind direction at which the wind loads are to be evaluated, the exposure of the building or structure shall be determined for the two upwind sectors extending 45° either side of the selected wind direction. The exposures in these two sectors shall be determined in accordance with Sections 6.5.6.2 and 6.5.6.3 and the exposure resulting in the highest wind loads shall be used to represent the winds from that direction.
6.5.6.2 Surface Roughness Categories. A ground surface roughness within each 45° sector shall be determined for a distance upwind of the site as defined in Section 6.5.6.3 from the categories defined in the following text, for the purpose of assigning an exposure category as defined in Section 6.5.6.3.
Surface Roughness B: Urban and suburban areas, wooded areas, or other terrain with numerous closely spaced obstructions having the size of single-family dwellings or larger.
Surface Roughness C: Open terrain with scattered obstructions having heights generally less than 30 ft (9.1 m). This category includes flat open country, grasslands, and all water surfaces in hurricane prone regions.
Surface Roughness D: Flat, unobstructed areas and water surfaces outside hurricane prone regions. This category includes smooth mud flats, salt flats, and unbroken ice.
6.5.6.3 Exposure Categories
Exposure B: Exposure B shall apply where the ground surface roughness condition, as defined by Surface Roughness B, prevails in the upwind direction for a distance of at least 2,600 ft (792 m) or 20 times the height of the building, whichever is greater.

assign Loads for Buildinas and Other Stnift-.roc