Reliability analysis and multi-level response modification factors for buckling restrained braced frames

Abstract

This study aims to assess the seismic performance of buckling restrained braced frames (BRBFs) using a probabilistic approach and develop multi-level response modification factors for performance-based design of these systems. Unlike traditional seismic design methods, the proposed response modification factors can take into account the seismic conditions of the site as well as the target design performance level. An engineering damage parameter method (EDP-Based) is adopted for reliability analysis of 4, 8 and 12 storey BRBFs using systems of parallel and serial components. In general, the results demonstrate the high seismic reliability of BRBFs for high levels of earthquake intensity. Considering the axial strain of the brace core as the local damage index, it is shown that the studied models remain in performance levels higher than life safety under the design hazard level (return period of 475 years). The upper bond response modification factor for the life safety and collapse prevention performance levels is estimated to be around 8.4 and 10.0 with the corresponding intensities of 0.68 and 0.85, respectively. Based on the outcomes of this study, in general, using a response modification factor between 4 and 8 for seismic design of BRBFs would guaranty their adequate performance under both the design basis and maximum considered earthquake levels.