Abstract
The ASCE/SEI 7 Standards Committee has incorporated a new Chapter 6, “Tsunami Loads and Effects,” in the 2016 edition of the ASCE 7 Standard, Minimum Design Loads and Associated Criteria for Buildings and Other Structures. The ASCE 7-16 chapter on “Tsunami Loads and Effects” is the first national, consensus-based standard for tsunami resilience, applicable to the states of Alaska, Washington, Oregon, California, and Hawaii. Furthermore, this new tsunami design standard is included in the requirements of the 2018 International Building Code. Taller structures in a community can provide effective secondary alternative refuge when evacuation out of the inundation zone is not possible or practically achievable for the entire population. Although Risk Category (RC) II buildings and structures are exempt from tsunami design according to the ASCE 7 Standard, local jurisdictions are encouraged to require tsunami design for RC II buildings and structures of designated occupancies exceeding an appropriate mean height, to provide more buildings that are life-safe and disaster resilient. It is necessary to evaluate several important technical factors to inform a jurisdiction’s decision to establish a threshold height of applicability for RC II buildings and structures; this evaluation requires structural engineering expertise as explained in this paper. For many locations in California, Oregon, and Washington, the current seismic design systemic capacity of buildings with minimum threshold heights that provide at least one level above the Maximum Considered Tsunami inundation level [between 7.62 m (25 ft) and 13.72 m (45 ft)] will be sufficiently strong to resist the overall tsunami design load. Coastal buildings with a minimum safe height above the inundation depth in several locations in Oregon and southern Washington would not have sufficient seismic design strength to resist tsunami loads. In these locations, options are discussed for implementing resiliency through tsunami strengthening and zoning policies.
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Acknowledgments
The support of the ASCE, Structural Engineering Institute, and the Coasts, Oceans, Ports, and Rivers Institute toward the development of the tsunami design provisions in ASCE 7-16 by the Tsunami Loads and Effects Subcommittee is gratefully acknowledged. The Tsunami Design Zone maps are developed by the University of Washington (UW). Yong Wei’s work was funded by the ASCE and UW Joint Institute for the Study of the Atmosphere and Ocean (JISAO) under NOAA Cooperative Agreement NA15OAR4320063 (2015–2020), UW/JISAO Contribution No. 2017-083, and PMEL Contribution No. 4641. The recommendations in this article are the authors’ conclusions based on the available information and do not imply endorsement or standards set by the US Federal Government or of the organizations supporting these authors.
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Published In
Journal of Structural Engineering
Volume 144 • Issue 8 • August 2018
Copyright
©2018 American Society of Civil Engineers.
History
Received: Apr 5, 2017
Accepted: Dec 29, 2017
Published online: Jun 11, 2018
Published in print: Aug 1, 2018
Discussion open until: Nov 11, 2018
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