Buckling-Restrained Braces (BRB) are becoming more popular in modern designs and retrofits of existing buildings due to their ductile, symmetric and full hysteretic characteristics. They also have the ability to be tailored for both strength and stiffness to meet specific design requirements. Analysis has shown that there may be discrepancies between the predicted ductility demand on BRBs determined from a nonlinear dynamic analysis and that determined from a code-based, equivalent static or elastic response spectrum analysis. Recent code changes have updated the drift requirements imposed on Buckling-Restrained Braced Frames (BRBF) in an effort to more accurately meet the ductility demands for BRBs. This paper will review the results of modeling of a 6-story BRBF building subjected to recorded and synthetic strong motion time histories and compare them to the code-required 2% story drift requirement as well as the ductility requirements of previous codes. It will also look at the effects of increasing the cross-sectional area of the BRB to achieve increased stiffness and the resulting ductility demands. The ground motions used in this study encompass near-field and far-field motions for two different seismic hazards. The research will suggest deformation ductility requirements that could be used for BRBF design and will comment on the applicability of the 2% story drift requirement in the current seismic provisions.
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