Changes to ASCE/SEI 4-2016 – Seismic Analysis of Safety-Related Nuclear Structures

ASCE/SEI 4-2016 Seismic Analysis Nuclear Structures Changes

ASCE/SEI 4-2016 – Seismic Analysis of Safety-Related Nuclear Structures has been released. This standard, developed by the American Society of Civil Engineers (ASCE), provides minimum guidelines and methods for the seismic analyses of safety-related structures of a nuclear facility, being applicable to above- and below-ground structures, buried piping, vertical liquid storage tanks, distribution systems, anchored and unanchored components, structures with seismic isolation systems, and similar structures in nuclear facilities.

ASCE/SEI 4-2016 revises the 1998 version of the standard for seismic analysis of safety-related nuclear structures, encompassing the great deal of information that emerged from developments in analysis procedures and the corresponding literature since the now-distant former release. Because of this, the changes made to the new standard are extensive.

Changes to ASCE/SEI 4-2016 include:

  • Chapter 2 on seismic input has been rewritten and expanded to emphasize performance-based design motions in keeping with the guidance in ASCE/SEI 43 and using methodology from NUREG/CR-6728 (2001), and it also includes a new section on probabilistic site response analysis.
  • Chapter 3, focusing on the modeling of structures, is an entirely new chapter, deriving from material from Section 3.1 of the 1998 edition.
  • Chapter 4, on the analysis of structures, is also a new chapter, and it traces its origins to Section 3.2 and Section of the previous version.
  • Chapter 5, covering soil-structure modeling and analysis, enhances upon much material from the previous publication, adding content for developing performance-based seismic input motions for use in soil-structure interaction analyses, as well as including a new section on probabilistic soil-structure interaction analysis.
  • Chapter 6 is a new chapter, on input for subsystem analysis, that updates material from the former Section 3.4.
  • Chapters 7 through 12 are also all new additions, dealing with special structures that require special treatment for seismic analysis, including: seismic analyses of buried piping and conduits (Chapter 7), analyses of the parts of nuclear facilities that are below grade (Chapter 8), analyses methods for aboveground liquid storage tanks (Chapter 9), analytical methods used for seismic analysis of mechanical and electrical distribution systems (Chapter 10), analysis of unanchored components (Chapter 11), and seismically isolated structures and components (Chapter 12).
  • Appendix A has been updated, addressing guidance identification of seismic vulnerabilities, along with other considerations beyond the design basis.
  • Appendix B is new, providing guidance for performing nonlinear three-dimensional time domain soil-structure interaction analysis.

As reflected in the changes noted above, ASCE/SEI 4-2016 is vastly different than ASCE 4-98. If you are interested in learning more about the standard and related documents and issues with seismic activity and nuclear structures, please refer to our companion post:

Seismic Analysis and Design Criteria of Nuclear Facilities

ASCE/SEI 4-2016 – Seismic Analysis of Safety-Related Nuclear Structures is available on the ANSI Webstore.

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