Performance-based Plastic Design Method for Buckling- Restrained Braced Frames

This paper presents the key design points of buckling-restrained braced frames (BRBFs) by using the performance-based plastic design (PBPD) methodology. This method is based on energy-work balance concept and uses pre-selected target drift and yield mechanism as design criteria. Based on multi-mode pushover and time-history analyses, a simple equation is developed for computing yield drift ratio, which is one of the essential parameters needs to be determined in the beginning of the design. The proposed equation accounts for higher mode effects as well as realistic boundary conditions of BRBs. In this study, two frames (one three-story and one six-story) were designed by PBPD method and their seismic performances were evaluated through nonlinear time-history analyses. It is shown that both frames showed intended yield mechanism and their drifts were well within the target drifts. The influence of P-Delta effect is also discussed.