Seismic performance evaluation of self-centering K-type and D-type eccentrically braced frame systems

摘要

This paper presents a numerical study of steel self-centering eccentrically braced frame (SCEBF) buildings subjected to seismic excitation. This study aims to investigate the nonlinear seismic system behavior of two types of SCEBF systems - K-type and D-type SCEBFs under design basis earthquake (DBE) level. Using two prototype framed structures - a 3-story D-type and a 4-story K-type SCEBF building designed for Los Angeles, California, it is demonstrated that SCEBF systems can be designed to provide the strength and stiffness comparable to conventional steel EBFs while maintaining plumbness under DBE level seismic ground motion excitation. The nonlinear time history analysis results show that residual drifts of the SCEBFs are negligibly small and damages in the structure are largely confined to fuse devices under DBE. Additionally, a parametric study of both K-type and D-type SCEBFs with three different levels of post-tensioning (PT) cables' initial stress has been done to demonstrate the approach to tuning the self-centering EBF's seismic behavior. The parametric study results suggest that key structural parameters such as the equivalent yield strength and the post-gap opening stiffness of SCEBFs can be adjusted through properly selecting PT cable's length and initial stress level.