Seismic Behavior and Design Approach of Variable-Damping Self-Centering Braced Frame

Abstract

In this paper, the seismic performance and resilience of a 15-story variable-damping self-centering braced frame (VD–SCBF) were analyzed. The interstory drift ratios (IDRs) of the VD–SCBF are similar to those of the buckling-restrained braced frame, but are lower than the prepressed self-centering braced frame (PS–SCBF). The residual deformation ratios (RDRs) of the VD–SCBF are reduced, and its story acceleration ratios are smaller than the PS–SCBF. Under near-fault earthquakes, the higher-order mode has a greater impact, which increases the inelastic response and ductility demand. The effects of the brace design parameters on structural performance were also investigated. The optimal design parameters are as follows: the activation displacement is appropriately small; the variable-damping region corresponds to the axial displacement of 1% IDR; the ratio of the prepressed force to initial Coulomb damping force is 1.0–1.1; and the viscous damping coefficient increases. Combining the damage development process of different components, the VD–SCBF can be designed based on its four seismic performance levels to ensure a reliable resilience.