Enhancing seismic performance of buckling-restrained brace frames equipped with innovative bracing systems

Abstract

AbstractNowadays, to improve the performance of conventional bracing systems, in which, buckling in the pressure loads is the main disadvantage, the buckling-restrained brace (BRB) is introduced as a solution. In this study, the performance of the BRB system was improved with innovative lateral-resisting systems of double-stage yield buckling-restrained brace (DYB), and a combination of DYB improved with shape memory alloy (SMA) materials (DYBSMA). The proposed systems have been verified and implemented in the 2- to 12-story elevation steel buckling-restrained brace frames (BRBFs). To evaluate their effects on the seismic performance, two types of analysis including nonlinear dynamic analysis (NDA) and incremental dynamic analysis (IDA) were performed considering design-based earthquakes (DBE) and maximum considered earthquakes (MCE) levels for far-field ground motions. The results showed that the BRB system in all BRBFs had the highest values of residual drift ratio (RDRMed) demands, while implementing innovative DYBSMA can considerably reduce the values of RDRMed compared to other lateral-resisting systems. In addition, under MCE level, the BRB-DYBSMA system had lower values of the interstory drift ratio (IDRMed) and RDRMed demands (e.g., the IDRMed reduced by 79.67% and 18.5% compared to BRB and DYB systems, respectively), and can be introduced as the best lateral-resisting system. Therefore, the proposed BRB-DYBSMA system can effectively reduce the IDRMed and RDRMed demands, as result, higher performance levels can be achieved, as well as, the collapse probability occurrence over 1 and 50 years impressively decreased.