Nonlinear seismic performance of Y-type self-centering steel eccentrically braced frame buildings

Abstract This paper presents the results from both analytical and numerical study of a Y-type self-centering eccentrically braced frame (SCEBF-Y) subjected to earthquake loading. In this study, a three-story SCEBF-Y frame building has been designed along with a three-story conventional D-type eccentrically braced frame (EBF-D) for a site located in Los Angeles, California. The analytical results reveal that initial stiffness and post-gap opening stiffness of SCEBF-Y depend on brace section properties and PT strand properties respectively. The finite element model of the SCEBF-Y frame has been verified with analytical results as well as experimental test data from a similar one-story one-bay D-type self-centering eccentrically braced frame specimen. The study results demonstrate that SCEBF-Y frame can be designed to the same strength and stiffness as conventional EBFs while it can re-center itself after design basis earthquake (DBE). In the SCEBF-Y system, replaceable energy dissipation devices termed RHD devices are installed to dissipate seismic energy, and the primary structural members are intended to remain elastic under the DBE earthquakes. The nonlinear time history analysis results for the prototype SCEBF-Y buildings show that not only the SCEBF-Y building has negligible residual drift, but also it has its major damage confined to replaceable energy dissipation devices. In the parametric study, three different levels of PT strands’ initial stress along with different PT cable length has been considered and the parametric study suggests that by properly choosing cable length and cable’s initial post-tensioning stress level, key structural system properties such as the post-gap-opening stiffness and the equivalent yield strength of SCEBF-Y can be adjusted accordingly.