Seismic Design and Performance of Buckling Restrained Braced Frames with Eccentric Brace Configurations Part 2: Analysis Studies and Design Implications

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This is the second of two companion papers discussing the seismic design and performance of buckling-restrained braced frames (BRBFs) with braces oriented in eccentric configurations. The companion paper (Li et al., 2026) introduces the proposed design procedures for the BRBFs with eccentricities and presents the elastic design results of nine case study buildings representing two building heights (12- and 3-story), two bracing configurations (chevron and single-diagonal), and various eccentricities. This paper first presents nonlinear response history analysis (NLRHA) results for the nine design case study buildings subjected to 16 ground motions scaled to the design basis earthquake (DBE) and maximum considered earthquake (MCE) levels. The analytical results demonstrate that BRBFs with eccentricities equal to twice the beam depth—double the current code limit of one beam depth—perform satisfactorily under seismic loading, provided they are properly capacity designed to account for brace eccentricities. The paper explores the relationship between brace eccentricity and key response parameters. The NLRHA results also validate the accuracy of the proposed analysis methods in estimating beam force demands in capacity design. Subsequently, nonlinear pushover analysis results for specific stories in selected chevron design cases are presented, with a focus on the effects of connection geometry, specifically combined and split gusset configurations, on local stress state in the beam region, analyzed through detailed finite element modeling. Lastly, the NLRHA results suggest that intentionally introducing brace eccentricities in single-diagonal BRBFs could potentially lead to more economical designs with enhanced seismic performance (e.g., reduced residual story drifts) as compared to concentric frames. Accordingly, design implications for single-diagonal eccentric BRBFs are explored, particularly concerning column capacity design with moment demands and the approximate story drift distribution for preliminary brace sizing.