Numerical Analysis of Steel Buckling-Restrained Braces with Varying Lengths, Gaps, and Stoppers

Abstract

The conventional buckling type of brace members offers lateral stiffness to the structural system; however, such members are likely to yield under tension and buckle under compression when loaded. Their unequal strength tends to produce higher demand on the framing system. Buckling-restrained braces (BRBs) offer excellent lateral force resistance, energy dissipation, and higher ductility thanks to their symmetrical hysteretic responses. The higher amount of friction, the gap between the core and restraining segment depending on the length, and the stoppers within the core segment are critical factors. This study investigates the effect of varying the yielding core length, the gap size between the steel core and the outer restraining segment, the position, and the frequency of stoppers on the hysteretic response of all-steel BRBs, considering the interaction between different parameters. Numerical analysis is performed with Abaqus finite-element software. A calibrated analytical model is used for the parametric study. The considered parameters are the cyclic behavior, axial resistance, energy dissipation capacity, compression strength adjustment factor, and strain hardening factor of the BRBs. Appropriate interface details are suggested based on the parametric finite-element analysis, considering the interactions among parameters. The study results reveal that the performance of BRBs with appropriate yielding core length, provided with sufficient gap size, is superior. Further, the selection of an appropriate gap size is of utmost importance. Finally, the provision of an increased number of stoppers enhances the performance of BRBs.