FMG128.xls
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Description
"FMG128" is a spreadsheet program written in MS-Excel for the purpose of determining Factory Mutual Global (FMG) required roof zone ratings for the three (3) zones of a roof, based on FMG Data Sheet 1-28 (2009/2011).
This program is a workbook consisting of two (2) worksheets, described as follows:
Doc
FMG Roof Uplift Ratings - Roof Wind Uplift Pressure Ratings per Factory Mutual Global 1-28
Program Assumptions and Limitations:
1. This program is based on the following reference:
Data Sheet 1-28: "Wind Design" - by Factory Mutual Global, 2009 (Revised April 2011)
2. In the "FMG Roof Uplift Ratings" worksheet, the FMG roof Zone 1 (Field Area) Rating is determined as follows:
a. Get Field Area design pressure from either Table 3, 4, or 5 depending on the Exposure, either B, C, or D.
b. Apply multiplier for Zone 1 from Table 6.
c. Apply a Factor of Safety multiplier of 2.
d. Round value up to the next highest 15 psf rating interval to arrive at the FMG Zone 1 (Field Area) Rating.
Note: for Zone 2 (Perimeter) and Zone 3 (Corners)
3. In the "FMG Roof Uplift Ratings" worksheet, the FMG roof Zone 2 (Perimeter) Rating is determined as follows:
a. Get Field Area design pressure from either Table 3, 4, or 5 depending on the Exposure, either B, C, or D.
b. Apply multiplier for Zone 2 from Table 6.
c. Apply a Factor of Safety multiplier of 2.
d. Round value up to the next highest 15 psf rating interval to arrive at the FMG Zone 2 (Perimeter) Rating.
4. In the "FMG Roof Uplift Ratings" worksheet, the FMG roof Zone 3 (Corners) Rating is determined as follows:
a. Get Field Area design pressure from either Table 3, 4, or 5 depending on the Exposure, either B, C, or D.
b. Apply multiplier for Zone 3 from Table 6.
c. Apply a Factor of Safety multiplier of 2.
d. Round value up to the next highest 15 psf rating interval to arrive at the FMG Zone 3 (Corners) Rating.
5. For components and cladding (roof deck, fasteners, and above deck components), FMG 1-28 requires that the effective area be set = 10 ft.^2 along with an Importance Factor = 1.15. For secondary supporting members (purlins or joists) per FMG 1-28 Section 2.2.3, refer to applicable ASCE 7 Standard and apply the appropriate effective tributary area along with an Importance Factor = 1.15.
6. This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc. (Note: presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell. Merely move the mouse pointer to the desired cell to view the contents of that particular "comment box".)
Calculation Reference
Roof Wind Uplift Pressure
Factory Mutual Global
Wind Loads
Calculation Preview
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At the bottom of the page, for "Zone 3 (Corner Area)......." the text was displaying "FMG Zone 2 (Perimeter Area) Pressure, p3 =", when it should have been displaying "FMG Zone 3 (Corner Area) Pressure, p3 =". This has now been corrected.
The current version of this workbook is now version 1.1.
You're welcome, and I'm glad that you find my spreadsheets useful.
The results of my FMG128.xls spreadsheet reflect the "Minimum Acceptable Design" wind pressures, as outlined in Table 1(page 5) from FMG-128, and are in line with what you would derive from using the ASCE7-5 Code.
By the way, keep in mind that the wind pressures per the newer ASCE7-10 Code are "factored" (LRFD). Thus, you'd have to factor down the results to be comparable to ASCE 7-05.