Design method and mechanical behavior of square section buckling restrained brace with two yield stages

A novel buckling restrained brace with two yield stages was proposed, which is able to yield and dissipate earthquake energy before the damage of the main structure component. Firstly, the mechanical model of the novel buckling restrained brace was established, and the equations of the yield capacity, the yield displacement and axial stiffness were deduced, and the failure modes and the design process of the novel brace were proposed. A total of 6 specimens in 2 groups were tested by static reciprocating loading experiment, showing that the novel braces perform good hysteretic performance and ductility, and verify the reliability of the equations recommended. Finally, the performance comparison with traditional buckling constraint brace was carried out. The results show that the yield capacities of the two types of braces are close, but the novel brace with low yield displacement performs the larger elastic stiffness and the smaller yield displacement. The yield displacement of the novel brace can be changed by modifying the design parameters of the brace, and the novel brace would dissipate the earthquake energy earlier and protect the main structure when a small yield displacement arrives. © 2016, Central South University Press. All right reserved.