Cyclic testing and performance evaluation of buckling-restrained knee-braced frames

This paper presents the behavior and design concept of an efficient structural steel system based on the applications of buckling-restrained knee braces (BRKBs). The advantages of a buckling-restrained knee-braced frame (BRKBF) include relatively simple connections, reparability after an earthquake, and fewer obstructions than conventional bracing systems. Various BRKBF configurations can be designed and detailed for different levels of strength, stiffness, and ductility. BRKBFs are designed so that all inelastic activities are confined to the BRKB. The key design concepts for ensuring the ductile behaviors of BRKBFs are first summarized. Cyclic tests of large-scale BRKBF sub-assemblage specimens are then carried out. The results from both experimental and analytical studies of the behavior of BRKBFs show that they can be a viable alternative to conventional structural systems.