Analysis and Design of Two-Tiered Steel Braced Frames under In-Plane Seismic Demand

Ali Imanpour, Robert Tremblay, Larry A. Fahnestock, Christopher Stoakes

Research output: Contribution to journalArticlepeer-review


A seismic design strategy, which is intended to be implemented within the framework of the U.S. seismic design provisions for steel structures, is presented for single-story steel concentrically braced frames that are divided into two tiers. In this method, the columns are designed to resist the axial loads acting in combination with the in-plane flexural demand resulting from uneven distribution of brace inelastic deformations over the frame height. This design procedure, which establishes enhanced requirements beyond the 2010 edition of the U.S. seismic design provisions, prevents concentration of deformation in one tier and causes frame nonlinear deformation to be distributed between the tiers. The column bending moments depend on the story shear resistance that develops in each tier when the bracing members are at buckling and in the postbuckling range. The method also aims to control tier drifts to protect the bracing members from excessive inelastic demand, which could cause brace fracture. Nonlinear static and dynamic analyses are performed to validate the proposed design procedure.

Original languageEnglish (US)
Article number04016115
JournalJournal of Structural Engineering (United States)
Issue number11
StatePublished - Nov 1 2016


  • Inelastic deformations
  • Metal and composite structures
  • Multi-tiered braced frames
  • Nonlinear analysis
  • Seismic design

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering


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