Dynamic performance comparison between buckling-restrained braced frames with concentric and eccentric configurations

Buckling-restrained braced frames (BRBFs) are often used in steel buildings to resist seismic loads; however, BRBF ductility can be limited by poor performance of the beam-column-gusset regions. Additionally, the concentric brace configuration in BRBFs can limit the use of architectural features, such as doors, windows, or halls. BRBFs with braces in eccentric configurations (called BRBF-Es) may accommodate architectural features similar to eccentrically braced frames, and limit damage to the connection regions through 1) the use of beam splices and 2) separation of the column-to-gusset connection which prevents pinching of the brace gusset plate. Similar to concentric BRBFs, seismic forces in BRBF-Es are dissipated through axial yielding of the buckling-restrained braces, while surrounding elements remain essentially elastic. In this study, the system-level and component-level dynamic performances of conventional BRBF systems are compared with those of BRBF-E systems. Multi-directional dynamic analyses are performed on 5-story BRBF and BRBF-E systems to compare drift demands and local connection demands. Modeling techniques are validated using experimental data for BRBFs. Results indicate similar stiffness between the BRBF and BRBF-E systems; however, with the BRBF-E, gusset connection stresses are greatly reduced due to the beam splices and eccentricity between the braced connection and column.