Probabilistic Seismic Performance Assessment of Rocking Buckling Restrained Braced Frames

One of the new lateral force-resisting systems introduced to improve seismic performance of structures is the rocking buckling restrained braced frame (RBRBF). In this system, conventional braces and adjacent columns are designed to remain elastic until near seismic collapse. In this paper, RBRBFs are designed according to a displacement-based design approach. Maximum interstory drift ratio (MIDR) and maximum residual interstory drift ratio (MRIDR) are among the most critical engineering demand parameters (EDPs) used to assess the safety of structures after an earthquake. MIDR is the largest peak interstory drift ratio (IDR) observed among all the stories of a structure. The primary aim of this study is to investigate the effects of utilizing RBRBFs on MIDR and MRIDR responses compared with buckling restrained braced frames (BRBFs). For this purpose, 4-, 8-, and 12-story structures with the RBRBF and BRBF systems are considered, and their collapse capacity values and residual drift capacity values, given different levels of MRIDR, are computed using incremental dynamic analyses (IDAs). After computing the capacity values, the mean annual frequencies (MAFs) of collapse ([Formula: see text]) and exceeding different MRIDR levels ([Formula: see text] are obtained. The results demonstrate that all the RBRBFs have considerably better collapse and residual drift performance than the BRBFs. Based on these results, the use of RBRBF significantly reduces the weaknesses of BRBF including damage concentration in a single story and low post-yield stiffness. Cloud analyses are performed on the structures to investigate the height-wise distributions of peak floor accelerations (PFAs), peak IDRs, and residual interstory drift ratios (RIDRs). The results indicate that the RBRBFs have a uniform height-wise distribution of peak IDR, but the BRBFs have considerable peak IDR concentrations. Furthermore, the RBRBFs have much lower RIDRs than the BRBFs, whereas they experience higher PFAs than the BRBFs. Nevertheless, their PFAs, on average, are not significantly higher than those of the BRBFs.