Self-centering Buckling-restrained Braces

Buckling-Restrained Brace (BRB) consists of energy dissipative core and a strengthening tube to prevent buckling when subjected to compression. Under cyclic loading, BRB exhibits elastoplastic hysteretic behavior, which leads to certain amount of permanent displacement in the structure after medium to severe earthquake. Residual deformations can result in increased cost of repairing. An innovative BRB device called Self-centering Buckling-Restrained Braces (SC-BRB) is devised to control maximum and residual drift of steel moment frame buildings subjected earthquakes. The SC-BRB is composed of the BRB energy dissipating cores which are responsible for energy dissipation, and the self-centering system which makes BRB energy dissipating core return to its initial position upon completely unloading. By exploring the mechanism of SC-BRB, it is found that to ensure fully self-centering capacity, the self-centering bar should have sufficient elongation capacity as well as considerably large elastic modulus which could afford stiffness in real structures.