ASCE has released an update to ASCE/SEI 41-23, Seismic Evaluation and Retrofit of Existing Buildings.
The consensus-based standard providing analysis procedures and specific requirements for buildings and other structures to withstand seismic impacts is the Society's second-biggest-selling standard, behind only ASCE 7.
The update includes provisions to align with the U.S. Geological Survey seismic hazard model and new provisions related to structural steel and reinforced concrete in existing buildings connected to standards published by the American Institute of Steel Construction and the American Concrete Institute.
Also published today: Tier 1 Checklists for Seismic Evaluation and Retrofit of Existing Buildings: Fillable Forms for Standard ASCE/SEI 41-23. Both are available on ASCE’s new interactive platform for standards ASCE AMPLIFY.
The Seismic Retrofit of Existing Buildings Standards Committee of the Codes and Standards Activities Division of the Structural Engineering Institute prepared the update – the work of more than 100 engineers over the course of thousands of volunteer hours, including subcommittee chairs Peter Somers, Dave Martin, Russ Berkowitz, James Parker, Terry Lundeen, Roy Lobo, Jay Harris, Wassim Ghannoum, Bill Tremayne, Phil Line, Brian Kehoe, and Reid Zimmerman.
All led by the committee chair Robert Pekelnicky, P.E., S.E., F.SEI, M.ASCE, who recently spoke with Civil Engineering Source about what civil engineers can expect to find in ASCE 41-23.
Civil Engineering Source: Let’s start at the beginning and outline generally what ASCE 41 does.
Bob Pekelnicky: Sure. ASCE 41 is a standard that provides the user a means to evaluate and retrofit a building for earthquake hazards, and it is intended specifically for existing buildings that would not conform to all the requirements of a new building standard.
The document is set up in a way that provides three different tiers of evaluation and retrofit approach, with each tier being more engineering-intensive but less conservative.
Source: As the committee began work, were there any earthquakes or disasters that altered your approach or what found its way into this update?
Pekelnicky: There really weren’t. This wasn’t like the 2017 cycle where we had the 2010 Chile and 2011 Christchurch earthquakes just before the kickoff of the cycle to have an influence.
But I would say that the 2023 Turkey-Syria earthquake, while it came late in the cycle, brought to the forefront the importance of having accurate standards for seismic evaluation and retrofit.
Source: I’d imagine that almost redoubles your focus when you’re seeing in real-time the importance of your work.
Pekelnicky: We always struggle, as standards writers, with balancing conservative provisions with less conservative provisions. Because if you have a standard where nothing works, then you don’t have a really good way to separate the really dangerous buildings from the maybe-not-as good-as-new-but-also-not-as-dangerous buildings.
So it’s really important to pull back that standards conservatism in that regard, but we also need to recognize – and I think the Turkey earthquake showed us this – how you can’t look at existing buildings through rose-colored glasses.
There are significant dangers, and the tragedy of that event just reinforced that.
Source: So when you look at the different things that are part of this update to ASCE 41, what do you think will be the most impactful change?
Pekelnicky: It’s difficult to say what the most impactful change will be.
For general users of the standard, one of the most impactful things is needing to go to documents published by collaborative partners and other standards-developing organizations – the American Concrete Institute and the American Institute of Steel Construction – for the provisions for reinforced concrete and structural steel, whereas they used to have that material all self-contained within ASCE 41. So that’s a major change for the users of the standard.
As for impacts on people using the standard in their projects, one of the biggest changes is the updated concrete wall provisions, which hadn’t really seen a substantial update since the predecessor documents of the standard in the late 1990s.
It’s been over 25 years since those provisions have been updated, and it coincides with a number of different local jurisdictions in the state of California either having already or having forthcoming ordinances requiring evaluation or, in many cases, retrofit of older concrete buildings.
So these updated provisions, which are for the most part less conservative than the provisions previously, will help people from consultants to building owners who have those types of building buildings covered by those ordinances.
There are also significant changes to the understanding of and seismic hazard parameters used for evaluation and retrofit thanks to additional work by the U.S. Geologic Survey.
And then [there are] just a lot of technical-update updates throughout the document that will have significant impacts on individual projects with evaluating a steel building; there are major changes for reinforced masonry buildings and also some changes for unreinforced masonry buildings.
So, it’s hard to really settle on what’s going to be the most impactful, because it really depends on the specific user’s practice.
And that’s what I’ve always found so great about ASCE 41: how broad a net this document casts across the practice of seismic evaluation and retrofit.
Learn more about ASCE 41-23.
Learn more about ASCE AMPLIFY.