Snow drift procedures in Canada and the U.S. are compared and evaluated.
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Author Archives : John F. Duntemann, P.E., S.E.
John F. Duntemann is a Senior Principal at Wiss, Janney, Elstner Associates in Northbrook, Illinois. He is the current Chair of the ASCE 7 Snow and Rain Subcommittee and a Fellow of the Structural Engineering Institute (SEI). (jduntemann@wje.com)
Part 2
The American Society of Civil Engineers’ ASCE 7-22 load standard, Minimum Design Loads for Buildings and Other Structures, is now available, and substantive changes have been made to both the snow and rain provisions. This article is the second in a two-part series regarding these changes. Part 1 (STRUCTURE, January 2022) reviewed changes to the ground snow loads, which represents a shift away from uniform hazard to uniform risk, and the addition of a winter wind parameter to account for the variability in winter wind speeds on drift loads. This article reviews other revisions to the snow loads, including a more accurate estimation of the horizontal extent of windward drifts, revised thermal factors Ct to account for current trends in roof insulation and venting, and guidance on design loads for snow capture walls added to this edition. Also, changes were made to Chapter 8 to include a ponding head to the rain load, which provides a consistent approach to assess ponding.
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Part 1
The American Society of Civil Engineer’s ASCE 7-22 load standard, Minimum Design Loads for Buildings and Other Structures, is now available. Substantive changes have been made to the snow and rain provisions within the standard. In particular, the ground snow loads have been revised to reflect more recent snow load data and reliability-targeted values. In addition, the method for estimating drifts has been revised to include a wind parameter, and the procedure for determining design rain loads has been revised to explicitly consider a ponding head. Some of the more substantive changes are discussed, along with the reasons for these changes. This article is Part 1 of a two-part series and reviews the new ground snow loads and a new winter wind parameter. Part 2 will include the other more substantive changes to the snow load provisions and the new rain load provisions.
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