ASCE705S is a spreadsheet program written in MS-Excel for the purpose of flat roof snow loading analysis for buildings and structures per the ASCE 7-05 Code. About the Author Michael O'Rourke, Ph.D., P.E., is a professor in the Department of Civil and Environmental Engineering at Rensselaer Polytechnic Institute, where he teaches and pursues snow load research. р f = design flat roof snow load. Non-shaded (CS) areas require site-specific Case Studies to establish ground snow loads. Snow load: (ASCE 7-05, 10, IBC 2006, 2009, 2012) ... Flat roof snow load: p f = 0.7 C e C t I s p g. C e is exposure factor. This program assumes only snow loading analysis for buildings with a flat roof, or low slope roof <= 5 degrees. The first is a simple, one story hip roof. I have the same question as Q2 about the snow load used. 7-1 F-6 PROTECTING MaNufaCTuREd HOMEs fROM flOOds aNd OTHER HazaRds A Multi-Hazard Foundation and Installation Guide. Herein the exposure and importance factors are taken to be 1.0. 2. or 1 in./ft.) 2. Maps of ground snow loads in IBC and in ASCE 7 indicate a 2 percent probability of the indicated load being equaled or exceeded in any given year. in ASCE 7-10, unbalanced snow load is not required for roof with slope > 30.2deg (or 7:12) ASCE702S is a spreadsheet program written in MS-Excel for the purpose of flat roof snow loading analysis for buildings and structures per the ASCE 7-02 Code. Flat Roof Snow Loads. Snow Loads: A Guide to the Use and Understanding of the Snow Load provisions of ASCE 7-02 is the only book that provides a detailed, authoritative interpretation of the snow load provisions of Minimum Design Loads for Buildings and Other Structures, Standard ASCE 7-02. р s = design snow load for a sloped roof. р g = ground snow load. Flat Roof Snow Load (p f) p f = 0.7C e C t Ip g p f = 0.7(1.0)(1.0)(1.0)(20) = 14 psf But not less than p f =(I)p g = 20 psf ASCE 7-05 Section 7.2 Figure 7-1 Section 7.3 Eq. If slope ≤ ¼” in 12”, design to prevent ponding. The International Code specifies design snow loads are to be determined according to Section 7 of a document called ASCE 7. Building Classification : Table 1-1, page 3: Ground Snow Load, pg: psf: Figure 7-1, pages 84-85 and Table 7-1, page 92: Length of High Roof, Lu: ft. For C t = 1.0 and I s = 1.0, Equation 7-1 produces ground-to-roof snow Pg = ground snow load Pf = flat roof snow load = Pg*I*Ce*Ct Ps = sloped roof snow load = Pf*Cs The "minimum" Pf is defined in ASCE-7-98 as: I*Pg when Pg is less than or equal to 20psf I*20 when Pg is greater than 20psf +++++ The "minimum" that is specified is for cases when the Ce*Ct<1.00. EXAMPLE CALCULATIONS F Section 7.3.1 Table 7-2 Section 7.3.2 Table 7-3 Section 7.3.3 … If slope ≤ ½” in 12”, add rain-on-snow surcharge (Section 7.10 ASCE 7) 2 yes . Specifically, coefficients and related and required parameters are selected or calculated in order to compute the net design snow loads, including snow drift due on lower roofs and rain-on-snow surcharge. Driven by recent changes to the ASCE 7 snow load provisions, this guide describes: The importance factor, also found in ASCE 7-10, takes into account the type of building for which you are calculating snow loads. "ASCE710S" --- ASCE 7-10 CODE SNOW LOAD ANALYSIS PROGRAM "ASCE710S" is a spreadsheet program written in MS-Excel for the purpose of flat roof snow loading analysis for buildings and structures per the ASCE 7-10 Code. This program specifically follows Section 7.0, Snow Loads, of the ASCE 7-05 Standard, "Minimum Design Loads for Buildings and Other Structures". However, I still have a hard time making sense of it when comparing the calculated drifting snow loads of building with very steep (say 12:12) roof and that with flat roof :) 2. ASCE 7 Table 7-3 Calculate flat roof snow load pf 0.7CeCt Is pg no Is roof flat? I = importance factor. Step 4 - Determine the Flat Roof Snow Load The complexity arises from the variable upwind fetch for unbalance or across-the-ridge drift loads. This program specifically follows Section 7.0, Snow Loads, of the ASCE 7-10 Standard, "Minimum Design Loads for Buildings and Other Structures". This document provides for all roof snow loads to be calculated from ground snow loads, however not every Building Department follows this procedure. Ground snow loads do not discount that actual snow loads may exceed them, only that the risk of snow-load-induced failure is reduced to an acceptably low level. , add Rain-on-Snow Surcharge Loadings, ASCE 7 ) 2 yes of a document called ASCE 7 ) yes... 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