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October 30, <br />2025 NEWPORT STRUCTURAL DESIGN – PROJECT NUMBER 2025-1305 <br /> <br />Wind Load <br /> <br />A portion of the duct sticks up above the roof: <br />Risk Category II <br />V = 95 mph (Figure 26.5-1A) <br />Kd = 1.00 (Table 26.6-1, Round) <br />Exposure C <br />Kzt = 1.0 (Section 26.8, Flat terrain) <br />Kz = 0.90 (Table 26.10-1, h = 20 ft) <br />qz = 0.00256*(1.0)*(1.00)*(0.90)*(95 mph)2 = 20.8 psf <br />Cf = 0.6 (Figure 29.4-1, Round, Smooth) <br />Therefore, Section 29.7 governs <br />Fwind = (16 psf)*(10”)*(48”) = 54 lbs <br />The spray booth is indoors so the design wind pressure is 5 psf at ASD level. At LRFD level, the <br />design wind pressure is 5 psf / (0.6) = 8.33 psf. <br /> <br />Roof Framing <br /> <br />The gravity load (a portion of 10” duct) being added to the roof is negligible <br />The hole being cut in the roof is not near any diaphragm edges, and the lateral force of 54 lbs is <br />negligible, therefore no lateral analysis of the roof was required. For the wind blowing in any <br />direction the duct is supported by at least two screws with more than enough capacity by <br />inspection (for wind/seismic). <br /> <br /> <br />