In the design of steel structures, seismic design provisions allow engineers only two classifications of moment frame design: special and ordinary moment frames (SMF and OMF). In certain circumstances, a steel structure's actual strength may be significantly higher than that required by seismic codes; therefore, the ductility demand can be much lower than a similar structure whose design is governed by strength. The author proposes a third classification for steel design: intermediate moment frame (IMF). This new classification would lead to more efficient steel designs. The paper reviews current design procedures and drift limit considerations and notes the dilemma regarding high-strength steel and its applications in high seismic regions. It notes that bridge designers have overcome this dilemma through use of the plastic moment concept. The author proposes an alternate design procedure that is rational, flexible, and simple for practical design. Specifically, the concept uses the reserve of structural strength resulting from the lateral stiffness requirement in the design process. Then, the ductility requirement is balanced with the actual strength of the structure. This methodology can easily be extended to braced frames.

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  • Supplemental Notes:
    • This article appears in a Special Conference Issue of Modern Steel Construction.
  • Corporate Authors:

    American Institute of Steel Construction

    One East Wacker Drive, Suite 3100
    Chicago, IL  United States  60601-2001
  • Authors:
    • Uang, C-M
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  • Publication Date: 1994-5


  • English

Media Info

  • Pagination: p. 52-57
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00663064
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 1 1994 12:00AM