Seismic performance assessment of buckling restrained braced frames based on resiliency aspects

The buckling-restrained braced frame (BRBF) is an appropriate lateral system for resisting seismic excitations. It is not yet an ideal system since there are deficiencies regarding the performance of this system. In this research resiliency of the reduced-length buckling restrained braced frames (RL-BRBFs) were assessed and compared with conventional buckling restrained braced frames (BRBF) as well as dual SMRF-BRBF. To do so two 4 and 9 story structures with conventional and reduced core length BRBs with diagonal and inverted chevron brace configuration were designed, then, the frames representing the lateral behavior of the structures were modelled in finite element software and time history analyses were performed on the structures under a set of 20 ground motion records. Seismic response of the structures including drifts and residual drifts were compared and reported herein. The results indicate that the reduced length BRBs have much better seismic behavior especially in the frame with moment resisting braced bay beam. The dual frame did not exhibit much different behavior compared to the braced frame with moment resisting braced bay beams. The moment resisting beams of the braced bays designed for the expected moment improved the drift response, plastic stiffness, and performed almost similar to the dual frame designed for 25% of the base shear. Furthermore, RL-BRBs are replaceable, repairable, and more cost-efficient compared to conventional BRBs due to smaller size of the reduced-length buckling restrained braces (RL-BRBF).