Seismic design and analysis of precast concrete buckling-restrained braced frames

Abstract

This paper describes a numerical evaluation of the seismic design of precast concrete buckling-restrained braced frames based on the Federal Emergency Management Agency’s Quantification of Building Seismic Performance Factors (FEMA P695) methodology. A set of 32 archetype braced frames covering a range of parameters were designed using a procedure consistent with current U.S. building code requirements. Nonlinear numerical models were developed and verified against existing experimental data. The results show that large axial compression and tension forces develop in both beams and columns, thus requiring these members to be designed with large reinforcement ratios or higher-grade reinforcing bars and beams to be designed like column members. Recommended beam and column effective (cracked) linear-elastic axial and flexural stiffness reduction factors provide reasonable estimates of story drifts and brace deformations under design lateral forces. Nonlinear monotonic static pushover and incremental dynamic analyses of the archetypes support an overstrength factor of 2.5, response modification coefficient of 8, and deflection amplification factor of 8 for the seismic design of this system.