Rethinking the Seismic Design of Chevron Braced Frames

Jeff Berman
Civil and Environmental Engineering, University of Washington

ABSTRACT: Steel braced frames are widely used as seismic force resisting systems; they provide high stiffness, good ductility, and competitive economy. In chevron or inverted-V configurations, braced frames also allow for architectural flexibility, and architects and structural engineers favored these configurations as recently as the early 1990s. In the late 1990s, updates to seismic design requirements resulted in very large beam sizes for chevron-braced frames, greatly reducing the economy of the system. Recent research has demonstrated that an alternative yield mechanism that relies on flexural yielding of beams in chevron frames provides seismic performance comparable or better than frames designed to current requirements, and the alternative significantly improves the system’s economics. Berman highlights the research that led to discovery of this alternative mechanism, the large-scale experiments and computational studies conducted, and the development of requirements for the system. The new requirements are to be implemented in the next update to AISC's Seismic Provisions for Structural Steel Buildings.

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