Chapter 6 WIND LOADS

€.1 GENERAL
'1.1 Scope. Buildings and other structures, including the Main " r-j-Force Resisting System (MWFRS) and all components and i.»:i.ting thereof, shall be designed and constructed to resist wind Liianis as specified herein.
• 1-2 Allowed Procedures. The design wind loads for buildings l: :'her structures, including the MWFRS and component and
-•OJing elements thereof, shall be determined using one of the fl«?'*ing procedures: (1) Method 1—Simplified Procedure as
-«i",'ned in Section 6.4 for buildings meeting the requirements »--. ";ed therein; (2) Method 2—Analytical Procedure as speci-i--: -^ Section 6.5 for buildings meeting the requirements speci-i-i -Terein; (3) Method 3—Wind Tunnel Procedure as specified
•:: aeoion 6.6.
«.'-* Wind Pressures Acting on Opposite Faces of Each Itmuding Surface. In the calculation of design wind loads for ir VA'FRS and for components and cladding for buildings, the
-:kt.uc sum of the pressures acting on opposite faces of each nu—ng surface shall be taken into account.
- Minimum Design Wind Loading. The design wind load, »•:.:•—ined by any one of the procedures specified in Sec-"m"i - ; .2, shall be not less than specified in this section.
-A.1 Main Wind-Force Resisting System. The wind load to i" &cij in the design of the MWFRS for an enclosed or partially •JHOooed building or other structure shall not be less than 10 Ib/ft2 '"" k-\/m2) multiplied by the area of the building or structure csed onto a vertical plane normal to the assumed wind direc-The design wind force for open buildings and other struc-Aall be not less than 10 Ib/ft2 (0.48 kN/m2) multiplied by the .lima i; ^
• ; Components and Cladding. The design wind pressure
ponents and cladding of buildings shall not be less than .«& .ressure of 10 Ib/ft2 (0.48 kN/m2) acting in either direction 1111—u to the surface.
- 3EFINITIONS
lowing definitions apply only to the provisions of
..*«,,»-: 6:
ndlTROVED: Acceptable to the authority having jurisdiction.
basic WIND SPEED, V: Three-second gust speed at 33 ft iflftikr above the ground in Exposure C (see Section 6.5.6.3) as
———ned in accordance with Section 6.5.4.
•H-DING, ENCLOSED: A building that does not comply -- requirements for open or partially enclosed buildings.
•.U-DING ENVELOPE: Cladding, roofing, exterior walls, .iBiBi- door assemblies, window assemblies, skylight assem-'•d other components enclosing the building.

BUILDING AND OTHER STRUCTURE, FLEXIBLE;
Slender buildings and other structures that have a fundamental natural frequency less than 1 Hz.
BUILDING, LOW-RISE: Enclosed or partially enclosed buildings that comply with the following conditions:
1. Mean roof height h less than or equal to 60 ft (18 m).
2. Mean roof height h does not exceed least horizontal dimension.
BUILDING, OPEN: A building having each wall at least 80 percent open. This condition is expressed for each wall by the equation Ao >_ O.&Ag where
Ao = total area of openings in a wall that receives positive external pressure, in ft2 (m2)
A, = the gross area of that wall in which Ay is identified, in ft2 (m2)
BUILDING, PARTIALLY ENCLOSED: A building that complies with both of the following conditions:
1. The total area of openings in a wall that receives positive external pressure exceeds the sum of the areas of openings in the balance of the building envelope (walls and roof) by more than 10 percent.
2. The total area of openings in a wall that receives positive external pressure exceeds 4 ft2 (0.37 m2) or 1 percent of the area of that wall, whichever is smaller, and the percentage of openings in the balance of the building envelope does not exceed 20 percent.
These conditions are expressed by the following equations:
1. Ao > LlOAo,
2. Ao > 4-sq ft (0.37 m2) or >0.01A,, whichever is smaller,
and ao,/a,, 5 0.20 where
Ao, Ag are as defined for Open Building
Ao; = the sum of the areas of openings in the building envelope (walls and roof) not including Ao, in ft2 (m2)
Agi = the sum of the gross surface areas of the building envelope (walls and roof) not including Ag, in ft2 (m2)
BUILDING OR OTHER STRUCTURE, REGULAR-SHAPED: A building or other structure having no unusual geometrical irregularity in spatial form.
BUILDING OR OTHER STRUCTURES, RIGID: A building or other structure whose fundamental frequency is greater than or equal to 1 Hz.
BUILDING, SIMPLE DIAPHRAGM: A building in which both windward and leeward wind loads are transmitted through floor and roof diaphragms to the same vertical MWFRS (e.g., no structural separations).
COMPONENTS AND CLADDING: Elements of the building envelope that do not qualify as part of the MWFRS.