Earthquake Induced Inelastic Demands on Buckling Restrained Braces

Abstract

Buckling restrained braces (BRBs) show an increasing popularity in modern designs due to their high ductility capacity over conventional braces. Non-linear tests on isolated BRBs have shown the symmetrical hysteresis properties of BRBs with roughly equal ultimate forces in both compression and tension. Further research is needed on the behavior of BRBs in braced frames and the system-level behavior of the buckling restrained brace frame (BRBF) system. This paper will investigate the effect of the stiffness and configuration of BRBs for BRBF system with different heights. This paper focuses on the behavior of three-story and six-story BRBF systems with normal yield length and shortened yield length BRBs for a chevron and single diagonal configuration designed for Los Angeles, CA and Riverside, CA. SAP2000 [CSI] and Perform 3D [CSI] were used for design and analysis of the models. Ground motions used in this study are scaled near-field and far-field motions with a 2 percent probability of exceedance in 50 years. The goal of the research is to evaluate the inelastic demands of the BRBs and the behavior of the BRBF systems induced by earthquakes and thus to provide further understanding of the BRBs.