Component testing, seismic evaluation and characterization of buckling-restrained braces

This paper reports on the results from a comprehensive component testing program on a type of buckling-restrained brace known as the Unbonded Brace(TM). The experimental data are used to: (1) verify the results of theoretical predictions on the structural stability of the braces; (2) validate the inelasitc capacity of the braces under severe earthquake demands; and (3) calibrate a macroscopic hysteretic model that is found to predict, with fidelity, the brace force-displacement behavior. The study concludes that the unbonded brace is a reliable and practical alternative to conventional framing systems to enhance the earthquake resistance of new and existing structures; capable of providing both the rigidity needed to satisfy structural drift limits, while delivering a substantial and repeatable energy absorption capability.