Comparative Assessment of the Seismic Behavior of Reduced‐Core Length and Conventional Buckling‐Restrained Bracing Systems

Abstract

AbstractThe buckling‐restrained braced frame (BRBF) is an appropriate lateral system for resisting seismic excitations. This system has high lateral stiffness and stable hysteretic loops mainly due to restraining global buckling of the brace core under compression. Even though BRB is an improved version of the conventional brace, it is not yet an ideal system since there are deficiencies regarding the performance of this system. Notable decrease of lateral stiffness after yielding of the BRB cores and significant residual drifts are instances of the deficiencies in BRBFs, which have been recognized as problematic and costly in recent earthquakes.Reducing the core length of the BRB can effectively increase the lateral stiffness as well as decreasing the drifts and residual drifts of the structure without any increase in the cross‐sectional area of the core. In this research nonlinear static pushover analyses have been conducted on 4 buildings including 4 and 9 story structures with conventional and reduced core length BRBs with diagonal and inverted chevron brace configuration. Both pinned and rigid end‐connections were considered for the beams in the braced bays. A 4‐story dual SMRF‐BRBF was included for better assessment of the contribution of frame action to the structural behavior. The results indicate that the reduced length BRBs have much better seismic behavior. Furthermore, they are replaceable, repairable and more cost‐efficient compared to conventional BRBs.