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Snow and Rain Loads in ASCE 7-22

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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Jan, 2022 By Michael O’Rourke, Ph.D., P.E. and John F. Duntemann, P.E., S.E. In Structural Loads Comments 0

The Long Road

Advancing First-Generation Performance-Based Seismic Design for Steel Buildings

Part 3: Future Efforts for All Structure Types

Capabilities to conduct a performance-based seismic design (PBSD) of retrofitted existing buildings and new buildings have advanced exponentially over the past 25 years. This progress has augmented our knowledge of building behavior given an earthquake intensity. Still, we must be cautious of considering a PBSD as an exact answer; instead, a PBSD gives us information to support decision-making. There is still much work needed to support PBSD capabilities, and this depends on the type of assessment being conducted. At the same time, a vision for the not-so-distant future must also be established.

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Jan, 2022 By Matthew S. Speicher, Ph.D. and John Harris, Ph.D. In Structural Design Comments 1

Two-Stage Analysis Loophole

Engineering projects and building code provisions can often seem like Rorschach tests where two people looking at the same thing can draw sharply different conclusions. This article reviews the two-stage analysis procedure in ASCE 7-16, Minimum Design Loads for Buildings and Other Structures, to consider if the provisions are an innocent inkblot or possibly may be interpreted differently by some.

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Jan, 2022 By Steven Shepherd, S.E. and James McDonald, S.E. In Structural Analysis Comments 0

The Hidden Cost of Copy and Paste

Part 2

In the first installment of this discussion (STRUCTURE, December 2021), I looked at 3 examples of bad habits in contract documents that can cause problems later for fabricators. This month, I offer an additional four examples.

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Jan, 2022 By Jason McCool, P.E. In Engineer's Notebook Comments 0

Niagara’s Upper Falls Bridge Failure

Leffert Lefferts Buck (STRUCTURE, December 2010) had long experiences with bridges across the Niagara River. First, he replaced wires and added anchorages to Roebling’s 1855 suspension bridge. He followed this with replacing the wooden trussing with iron and, still later, he replaced the stone towers with iron, all of these without stopping traffic for any extended period. These modifications took place between 1877 and 1886. With his associate R. S. Buck, he replaced Edward W. Serrell’s Lewiston/Queenston Suspension Bridge in 1889. He widened and strengthened Samuel Keefer’s 1868 Honeymoon Suspension Bridge in 1888. Unfortunately, the deck collapsed in a fierce windstorm in 1889, shortly after it opened. He rebuilt it within two months. In 1895, the owners wanted to widen the bridge and have it support trolley traffic. Buck was chosen to design and build an arch bridge under and around his bridge in 1897. He chose a braced arch, open-spandrel span of 840 feet that made it the longest arch span in the world when it opened on June 20, 1898.

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Jan, 2022 By Frank Griggs, Jr., Dist. M. ASCE, D. Eng., P.E., P.L.S. In Historic Structures Comments 0

Building Safety Assessments Following the Sparta Earthquake

A magnitude 5.1 earthquake struck near Sparta, North Carolina, on August 9, 2020, at 8:07 a.m. local time. The event was the strongest North Carolina earthquake since 1916, producing “very strong” shaking and over 100,000 Did You Feel It? reports throughout the southern, midwestern, and northeastern United States. More than 500 residential and commercial structures were damaged during the quake. As a result, North Carolina Emergency Management deployed eight post-disaster building safety evaluators, including four engineers, to evaluate the damaged structures for safe occupancy.

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Jan, 2022 By Colby Baker, P.E. In InSights Comments 1

Positioning for Continued Success

January typically prompts business planning for a new year. However, since early 2020, the Covid-19 pandemic has made business planning and operations much more volatile. While we all have learned to be more resilient to thrive, it is difficult to gauge when companies will experience more stable economic conditions. This article offers some insight into economic conditions and how to position your company to continue to be successful in the coming months.

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Jan, 2022 By Kacey Clagett, LEED AP BD+C and Tiany Galaskas In Business Practices Comments 0

Edmonton’s Stanley A. Milner Library

Creativity in Design and Execution

A landmark of its time, the Stanley A. Milner Library has lived in the civic heart of downtown Edmonton since 1967. For the expansion and renovation of the monolithic concrete library, the design team was challenged to modernize its Brutalist-style for the 1.2 million visitors it receives every year. Transforming the original concrete façade into a floating, streamlined structure would be no small task. Fast + Epp responded by completely replacing the existing façade with a geometrically complex structure at the north face of the building and incorporating a new lateral system for the building.

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Jan, 2022 By STRUCTURE magazine In Spotlight Comments 0

Invest in Your Success and the Future of Structural Engineering

How much are you willing to invest in your success? Structural engineers spend $10s, if not $100s of thousands preparing to launch their careers technically. And that is usually sufficient for the first five years of a career. Beyond this, what are you personally investing to enhance your career and your practice? For our practices, firms, and companies to grow and thrive requires competent people, 21^st-century solutions to address 21^st-century problems, business savvy, and more. Ensuring a strong pipeline of people, solutions, and business aids necessitates collective investment. No one firm can accomplish this alone. This is where the SEI Futures Fund comes in.

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Dec, 2021 By Anne M. Ellis, P.E., FACI, F.ASCE In Editorial Comments 0

Automation and the Future of Structural Engineering

In July 2021, I discussed the “hot” topic of automation and the future for structural engineers with two of the industry’s leading experts in digital design: Rob Otani is a Senior Principal and the Chief Technology Officer at Thornton Tomasetti, and Zak Kostura is an Associate Principal and the Americas Region leader of Advanced Digital Engineering at Arup. Below are highlights from our discussion.

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Dec, 2021 By Eytan Solomon, P.E., LEED AP In InFocus Comments 0

Current Issue	Resource Guide

Review Category : Articles

Part 1

Advancing First-Generation Performance-Based Seismic Design for Steel Buildings

Part 3: Future Efforts for All Structure Types

Part 2

Creativity in Design and Execution