"ASCE705S" Program

Doc"ASCE705S" --- ASCE 7-05 CODE SNOW LOAD ANALYSIS PROGRAMProgram Description:"ASCE705S" is a spreadsheet program written in MS-Excel for the purpose of flat roof snow loading analysis forbuildings and structures per the ASCE 7-05 Code. Specifically, coefficients and related and required parametersare selected or calculated in order to compute the net design snow loads, including snow drift due on lower roofsand rain-on-snow surcharge.This program is a workbook consisting of three (3) worksheets, described as follows:Worksheet NameDescriptionDocThis documentation sheetSnow LoadSnow loading analysis for buildings with flat or low slope roofsSnow MapGround snow loads map (Figure 7-1 of ASCE 7-05 Code)Program Assumptions and Limitations:1. This program specifically follows Section 7.0, Snow Loads, of the ASCE 7-05 Standard, "Minimum DesignLoads for Buildings and Other Structures".2. This program assumes only snow loading analysis for buildings with a flat roof, or low slope roof 20 psf, nor for roof slopes (in degrees) >= W/50,where "W" is equal to the horizontal distance (in feet) from the eave to the ridge on the building.This program conservatively combines the rain-on-snow surcharge loading with snow drift loading. However,per Code, rain-on-snow surcharge loading need not be combined (superimposed) with snow drift loading.6. This program contains numerous comment boxes which contain a wide variety of information includingexplanations of input or output items, equations used, data tables, etc. (Note: presence of a comment boxis denoted by a red triangle in the upper right-hand corner of a cell. Merely move the mouse pointer to thedesired cell to view the contents of that particular "comment box".)

Snow LoadSNOW LOADING ANALYSISCALCULATIONS:Version 1.7Per ASCE 7-05 Code for Buildings with Flat or Low Slope Roofs (=25'Horiz. Dist. from Eave to Ridge, W =150.00ft.Horizontal Distance from Eave to Ridgehdw =3.43ft.hdw = 0.75*(0.43*LL^1/3*(pg+10)^1/4-1.5) with LL>=25'Type of Roof =MonoslopeType of Roof = Monoslope, Gable, or Hiphd(max) =3.81ft.hd(max) = maximum of: (hdL or hdw)Obstruction Height, ho =4.00ft.High Roof - Low Roof ElevationsRatio: hc/hb =1.29If hc/hb >= 0.2 , then snow drifts are required to be appliedRoof Slope, S =0.00in./ft.S = Rise per foot of Runw =25.77ft.If hd(max)hc: w = 4*hd(max)^2/hcExposure Factor, Ce =1.00Table 7-2, page 92hd =2.25ft.If hd(max) hc: hd = hcThermal Factor, Ct =1.20Table 7-3, page 93w(max) =18.00ft.w(max) = minimum of: 8*hc or LLw(use) =18.00ft.w(use) = minimum of: w or w(max)Results:pd =43.20psfpd =hd*g (maximum value)Roof Angle, q =0.0000deg.q = ATAN(S/12)pde =0.00psfpde = 0, as Low Roof Length (LL) >= w(max)Importance Factor, I =1.00Table 7-4, page 93prs =0.00psfprs = 5.0 psf when 0 < pg =25' (Figure 7-9)Windward Drift Height, hdw =3.43ft.hdw = 0.75*(0.43*LL^1/3*(pg+10)^1/4-1.5), with LL>=25'Max. Drift Height, hd(max) =3.81ft.hd(max) = maximum of: (hdL or hdw)Ratio, hc/hb =1.29If hc/hb >= 0.2 , then snow drifts are required to be applied0Drift Length, w =25.77ft.If hd(max)hc: w = 4*hd(max)^2/hcDesign Drift Height, hd =2.25ft.If hd(max) hc: hd = hcDrift Length, w(max) =18.00ft.w(max) = w(max)NOT required for pg > 20 psfRain-on-Snow Surch., prs =0.00psfprs = 5.0 psf when 0 < pg