The cast steel Yielding Brace System is a non-buckling concentric bracing system that dissipates earthquake energy through the flexural yielding of elements of a specially designed Yielding Connector. The Yielding Connector’s hysteretic response is characterized by an increase in stiffness at large (inelastic) displacements due to a second-order geometric effect. Results of a numerical study on building structures designed using Yielding Connectors are presented. A twelve-story sample structure designed with both buckling restrained braces and Yielding Connector-equipped braces was subjected to time-history analyses in an effort to examine the effect of post-yield stiffening on the collapse performance of buildings. The building designs were modeled with OpenSees, and the Yielding Connectors were simulated with an experimentally validated phenomenological material model. The non-linear time-history analyses were performed with a suite of seven ground motions scaled to the Design Earthquake and Maximum Considered Earthquake seismic hazard levels.
The effect of increased brace and brace connection strengths on collapse performance is also explored. The study confirmed that, when included in the capacity design of the braces and brace connections, post-yield stiffening and strengthening can decrease the likelihood of a structural collapse during a significant earthquake.