FAQ on SEI Standards

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This quarterly article addresses some of the questions received about structural standards developed by the Structural Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE). Questions from engineers, building officials, and other design professionals are often considered to develop future editions.

These topics and more are discussed on the ASCE Peer-to-Peer Standards Exchange Forum. ASCE/SEI members can ask and answer questions in the forum. Visit https://collaborate.asce.org/standards-exchange/home to learn more and read about other topics.

I have a time-sensitive question regarding SEI standards. Is there a way to get a quicker response than waiting for the quarterly FAQ to be published in STRUCTURE?

Answer: The fastest way to receive a response is to ask Eaves, ASCE AMPLIFY’s new AI Assistant. Eaves can answer questions on nine of SEI’s 21 published standards: ASCE/SEI 7: Minimum Design Loads and Associated Criteria for Buildings and Other Structures, ASCE/SEI 8: Specification for the Design of Cold-Formed Stainless Steel Structural Members, ASCE/SEI 19: Structural Applications of Steel Cables for Buildings, ASCE/SEI 24: Flood Resistant Design and Construction, ASCE/SEI 29: Standard Calculation Methods for Structural Fire Protection, ASCE/SEI 32: Design and Construction of Frost-Protected Shallow Foundations, ASCE/SEI 41: Seismic Evaluation and Retrofit of Existing Buildings, ASCE/SEI 49: Wind Tunnel Testing for Buildings and Other Structures, and ASCE/SEI 55: Tensile Membrane Structures.
You can also search questions and responses on the ASCE Peer-to-Peer Standards Exchange Forum. While ASCE membership is required to post a question or an answer, membership is not required to view the forum.

What is the resolution used in the ASCE 7-22 snow load maps?

Answer: The ASCE 7-22 Design Ground Snow Load Geodatabase provides values for the conterminous United States on an approximately one-half mile by one-half mile grid. To see the variation in snow loads across a region, use the Overlay slider under the View Results tab in the ASCE Hazard Tool. For areas with a significant elevation difference over a short distance, compare the Mapped Elevation provided in the Details tab with the actual elevation of your site. In instances of significant difference over 500 feet, use the Find on Map option to select a location up to one-half mile away with a Mapped Elevation that better matches the actual elevation of your location.

When the “Default” site class is selected, does the ASCE Hazard Tool find the most critical design spectral response acceleration parameters for site classes C, CD, and D and provide as the output the most critical parameters (envelope)?

Answer: Yes.

Minneapolis, Boston, and Baltimore have very different climates. How is it that they all have similar ground snow loads in ASCE 7-22 when they were significantly different in ASCE 7-16?

Answer: The ground snow loads in ASCE 7-22 are reliability-targeted loads that are determined through probability analysis. In locations like Minneapolis where precipitation during the winter months regularly falls as snow instead of rain, there is less year-to-year variability in the annual maximum ground snow loads and the reliability-targeted load is less than 1.6 times the 50-year MRI load. Baltimore, where the average coldest month temperature hovers right above freezing, has more potential for variability, and the reliability-targeted load is more than 1.6 times the 50-year MRI load. Boston falls in the middle where the reliability-targeted load is very close to the 50-year MRI load. The ASCE 7-16 ground snow loads had the same annual probability of occurrence at each location but resulted in different annual probabilities of failure. The ASCE 7-22 ground snow loads have different annual probabilities of occurrence at each location but result in the same annual probability of failure when used for design.

This article’s information is provided for general informational purposes only and is not intended in any fashion to be a substitute for professional consultation. Information provided does not constitute a formal interpretation of the standard. Under no circumstances does ASCE/SEI, its affiliates, officers, directors, employees, or volunteers warrant the completeness, accuracy, or relevancy of any information or advice provided herein or its usefulness for any particular purpose. ASCE/SEI, its affiliates, officers, directors, employees, and volunteers expressly disclaim any and all responsibility for any liability, loss, or damage that you may cause or incur in reliance on any information or advice provided herein.

If you have a question you want to be considered in a future issue, please send it to sei@asce.org with FAQ in the subject line. Visit asce.org/sei to learn more about ASCE/SEI Standards. ■

About the Author

Jeannette Torrents, PE, SE, F.SEI, is the Technical Director of the Structural Engineering Institute.