Experimental and Finite Element Study of Cantilever Stiffened Buckling-Restrained Brace

In civil engineering, Buckling-Restrained Braces (BRBs) have gained wide recognition for their effectiveness in improving seismic performance and dissipating energy. However, one of the significant challenges of unfilled BRBs is controlling local buckling. To solve this issue, this study has developed the Cantilever Stiffened Buckling-Restrained Brace (CAS-BRB). This system employs a low-yield steel core and a cantilever-type stiffener between the core flanges to prevent local buckling, making it highly stable and reliable. The design ensures that the tension length remains unaffected. When a tensile load is applied, the cantilever length does not occupy the displacement-bearing length, reducing the core deformation rate. On the other hand, when a compression load is applied, the core experiences buckling, and the stiffener comes into contact, constraining local buckling and enhancing rigidity. This study aims to meet the performance certification criteria without bearing force degradation when the new type of BRB is applied according to the AISC 341-22 loading protocol. Moreover, it seeks to analyze the impact of the stiffener length on the performance of the brace and determine whether the difference between the newly proposed Cantilever Stiffened Buckling-Restrained Brace (CAS-BRB) becomes a buckling constraint. The effectiveness of this innovative design was validated through experiments, and an efficient cantilever length was derived as a variable, further highlighting its efficacy.