2900 GRAND AVE FARMERS MARKET 2020-04-06

MINIMUM DESIGN LOADS PART 2: LOW-RISE BUILDINGS User Note:Part 2 of Chapter 30 is a simplified method (SIMPLIFIED) to determine wind pressures on C&C of enclosed low rise buildings having flat,gable or hip roof shapes. 30.5 BUILDING TYPES The provisions of Part2 are based on the Envelope Procedure of Part 1 with wind pressures determined The provisions of Section 30.5 are applicable to an from.a table and adjusted as appropriate. enclosed: -Low-rise building(see definition in Section 26.2) -Building with h<-60 ft(18.3 m) The building has a flat roof,gable roof, or hip roof. Table 30.5-1 Steps to Determine C&C The steps required for the determination of wind loads Wind Loads Enclosed Low-rise Buildings on components and cladding for these building types (Simplified Method) are shown in Table 30.5-1. Step 1:Determine risk category,see Table 1.5-1 30.5.1 Conditions Step 2: Determine the basic wind speed, V,for For the design of components and cladding the applicable risk category see Figure 26.5-1A, building shall comply with all the following B or C conditions: Step 3: Determine wind load parameters: 1. The mean roof height h must be less than or equal D Exposure category B,C or D,see to 60 ft(18.3 m) (h<_60 ft(18.3 m)). Section 26.7 2. The building is enclosed as defined in Section 26.2 D Topographic factor,K„see Section 26.8 and Figure 26.8-1 and conforms to the wind-borne debris provisions of Section 26.10.3. Step 4:Enter figure to determine wind pressures at 3. The building is a regular-shaped building or h=30 ft.,p„,,,,,see Fig. 30.5-1 structure as defined in Section 26.2. Step 5:Enter figure to determine adjustment for building 4. The building does not have response characteristics height and exposure,a,see Fig.30.5-1 making it subject to across wind loading, vortex Step 6: Determine adjusted wind pressures,p,,„see shedding,or instability due to galloping or flutter; Eq.30.5-1. and it does not have a site location for which channeling effects or buffeting in the wake of upwind obstructions warrant special consideration. 5. The building has either a flat roof,a gable roof with 0<-45°,or a hip roof with 0<-27°. 30.5.2 Design Wind Pressures Net design wind pressures,p„,„for component and cladding of buildings designed using the proce- dure specified herein represent the net pressures(sum of internal and external)that shall be applied normal • to each building surface as shown in Fig. 30.5-1.p„e, shall be determined by the following equation: Pnei= zrPner3o (30.5-1) where X=adjustment factor for building height and expo- sure from Fig. 30.5-1 K„=topographic factor as defined in Section 26.8 evaluated at 0.33 mean roof height, 0.33h Pnet3o=net design wind pressure for Exposure B, at h =30 ft(9.1 m), from Fig. 30.5-1 319