Concentrically Braced Frame Provisions in AISC 342: Evaluation and Retrofit

by Dawn Lehman, Ph.D.

January 12, 2023; 11:00 AM - 1:00 PM Pacific Time

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ICC Preferred Provider Course Number: 34562

Seminar Description

Concentrically braced frames (CBFs) have been used as seismic lateral force resisting systems for many years, but current seismic design provisions were not instituted until about 1995. Hence many older braced frames in seismic regions do not meet current seismic design requirements. The seismic rehabilitation design standard, ASCE 41, is nominally intended to address the seismic performance and retrofit of these older buildings. However, the ASCE 41 provisions for braced frames were developed in early 1990’s, which both preceded development of current AISC 341 for SCBFs and current research on older and retrofitted CBFs. The AISC 342 standard has been approved and is being further updated to replace ASCE 41 provisions for seismic evaluation and retrofit of steel buildings. AISC 342 will update all steel provisions, but it particularly updates provisions for braced frames, since there has been extensive research on the seismic performance of braced frames in the past 20 years. This session will show the background to these AISC 342 braced frame provisions, the changes made in the provisions, the consequences of the changes, and an example application of the new provisions.

1. Brief review of current SCBF capacity-based design requirements including historical development of current braced frame design provisions
2. Review of common deficiencies of braced frames designed before AISC 341.
3. Discussion of experimental research results for frames with these deficiencies
4. Development of improved retrofit provisions to address these deficiencies
5. Braced frame modeling provisions adopted by AISC 342
6. Example application

Speaker Bio

Dawn Lehman is a Professor of Civil and Environmental Engineering at the University of Washington. She received her BS from Tufts University in 1989 and her PhD from U.C. Berkeley in 1989. She worked as a structural engineer in Boston MA between these degrees. She has been a faculty member at the University of Washington since 1999. Her research expertise lies in seismic engineering of structural systems. She has conducted research on a range of systems including reinforced concrete walls and frames, steel braced frames, as well as concrete-filled-tube, precast and reinforced-concrete bridge systems. Her research results have been implemented in codes, design manuals and provisional structural engineering recommendations, including AASHTO, AISC, WSDOT BDM, Caltrans SDM, and ASCE 41. She has authored over 90 peer-reviewed research articles. She led the technical investigation of the CTS collapse as a consultant to the Miami Herald.

Registration Information

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* Registration on or before January 10, 2023

Please note a single registration allows you to have one connection. However, a number of people can view and listen to the seminar using one connection by using an LCD projector (or a large computer monitor) and good computer speakers or a speaker phone.

All attendees, irrespective of the number of registered connections, can earn 0.2 Continuing Education Units (CEUs) or 2.0 professional development hours (PDHs). CEU/PDH certificates are provided free of charge.

FAQ

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• A $15 fee will apply if the seminar registrant wishes to revise the web seminar registration (e.g. switch from one web seminar to another).
• Refunds are limited to 80 percent of fee and must be applied for in writing WITHIN THIRTY DAYS after the scheduled seminar.
• We are a registered provider for continuing education in the State of Florida (Provider # 4732), the State of New York (Provider # 99), the State of New Jersey (Provider # 24GP00014200), the State of Maryland, and for the Structural Engineers Certification Board (SECB) of the National Council of Structural Engineers Associations (NCSEA).