ABSTRACT
Due to buckling of bracing member, ductility of concentrically braced steel frames is limited and this leads to some limitations on the use of this system for seismic design particularly in the seismic zone (Bruneau et al. 1998) while this system due to its high elastic stiffness can be considered one of the best options for control of structure drift. Thus extensive attempts have been made to improve the ductility of these frames that lead to create new lateral resisting systems such Buckling Restrained Braced Frames (BRBFs) (Watanabe, A., et al. 1988). The idea applied to BRBFs is to increases the overall stability of brace till yielding of its central core.
