Draft

2.3LateralLoads 37

Thus,thedesignpressurep(psf) is givenby

p=CeCqIqs (2.6)

Thepressureis assumedto benormalto allwallsandroofsand

CeVelocity PressureCoecientaccounts forheight, exposureandgustfactor.It accounts

forthefactthatwindvelocity increaseswithheight andthatdynamiccharacterof the

air
ow (i.ethewindpressureis notsteady),Table2.6.

Ce Exposure

1.39-2.34 D Open,
atterrainfacinglargebodiesof water

1.06-2.19 C Flatopenterrain,extendingone-halfmileor openfromthe

sitein any fullquadrant

0.62-1.80 B Terrainwithbuildings,forest,or surfaceirregularities 20 ft

or morein height

Table2.6:CeCoecients forWindLoad,(UBC1995)

CqPressureCoecient is a shape factorwhich is givenin Table2.7forgabledframes.

WindwardSide LeewardSide

GabledFrames(V:H)

Roof Slope <9:12 0 : 7 0 : 7

9:12to 12:12 0 : 4 0 : 7

12:12 0 : 7 0 : 7

Walls 0 : 8 0 : 5

Buildings(height< 200 ft)

VerticalProjections height<40 ft 1 : 3 1 : 3

height>40 ft 1 : 4 1 : 4

HorizontalProjections 0 : 7 0 : 7

Table2.7:WindPressureCoecientsCq, (UBC1995)

IImportanceFactoras givenby Table2.8. where

I EssentialFacilities: Hospitals;Fireandpolicestations; Tanks;Emergencyvehicle

shelters,standby power-generatingequipment; Structuresandequipment in govern-

ment. communicationcenters.

II HazardousFacilities: Structureshousing,supportingor containingsucient quan-

titiesof toxicor explosive substancesto be dangerousto thesafety of thegeneral

publicif released.

III Specialoccupancystructure: Coveredstructureswhoseprimaryoccupancyis pub-

licassembly, capacity> 300 persons.