09-9141 - Laserfiche WebLink

Browse Search

The following information contains the requirements for a roof - mounted system designed for a wind loading negative 61.5 ( -61.5) pounds per square foot (PSF) corresponding to a wind velocity of 155 miles per hour. This is a higher design pressure than is required in central Florida. This installation will meet F.B.C. 2003 for Florida. Supporting data is provided and analyzed at the new design pressure of 61.5 psf for coastal regions. The Sealed Air FS, FW, and FP series panels have been tested by Hurricane Test Engineering Inc. of Miami Florida at test pressures of ( -60 psf), ( -90 psf) and ( -120 psf). The framed series panels are attached directly to the roof structure (securely into rafters) per installation instructions by factory retaining clips tested to retain the panel at a loading of 95 psf. Use the factory recommended clip arrangement with factory supplied HSS #14 (1/4 ") lag screws having a minimum tensile strength of 45,000 psi, secured by 1/4" zinc plated thrust washers. To calculate the uplift force of the section of panels, use the formula: (P) x (A) x (N) Where: P = Pressure per square foot on the panel surface for the design velocity. A = The width x length of the panel. N = Number of panels mounted on the roof. Example: For the following example, the largest array of the largest collector is used to demonstrate the maximum exposure. Arrays should be limited to 11 collectors or less per bank for thermal performance reasons. All charts supplied have been calculated on the new maximum design pressure of 61.5 psf., and the anchorages are prorated to reflect the higher values. The total uplift of an l 1panel section of 4' x 12' collectors at a wind loading of 61.5 psf would be: 61.5 x 4 x 12 x 11 = 32,472 1b. Lag bolt pull out force is calculated by the thread strength of the lag, and the ability of wood to hold the lag in place. As the length of the lag increases the wood's ability to hold the lag increases until the tensile strength of the bolt is reached. Wood typically used in building roof structures is softwood having a specific gravity of 0.55. The lag bolt pull out force must exceed the uplift force determined above in order to keep the solar array (panel section) in place. The following pull out force is given for lag bolts in wood substrate. Forces are per inch of length imbedded in wood. 1/4" = 260 1b./inch 3/8" = 390 lb. /inch Pull out force can be expressed as follows: Pf =SxL Page 2 of 4