The Effect of Yielding-Core Lengths on the Seismic Behavior of BRBFs
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Volume Title: ICASGE2023
DOI: ICASGE-STA
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Abstract
Steel frames equipped with Buckling Restrained Braces (BRBs) are considered to be an efficient lateral force-resisting systems in high seismicity regions. Yielding of the BRB steel core causes nearly symmetric hysteretic response in tension and compression that helps the Buckling Restrained Braced Frames (BRBFs) to exhibit superior ductility and energy dissipation capabilities. However, due to the low axial stiffness of BRBs, the post-earthquake residual drift may be very excessive under strong ground motions. Recent studies have recommended shortening the BRB yielding-core length to enhance the elastic and inelastic axial stiffnesses of the BRBs and consequently controlling the excessive residual drifts of the BRBFs. The purpose of this study is to analytically evaluate the seismic response of BRBFs having different yielding-core lengths. The study also investigates the feasibility of using short yielding core lengths. Static pushover and dynamic-time history analyses were performed on a 6- story prototype building equipped with BRBs having short, medium and long yielding core lengths. The parameters evaluated in this study are the story drift ratio (SDR), the residual-SDR, and the BRB strain demands. The results of this study showed that BRBF systems having short yielding-core BRBs display reduced maximum and residual lateral drifts in comparison with long yielding-core BRBF systems. In addition, short yielding-core segments sustain large plastic deformations as compared to longer yielding-core systems.
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