Development of novel SMA-based D-type self-centering eccentrically braced frames

In this study, a novel D-type self-centering (SC) eccentrically braced frame (EBF) based on superelastic shape memory alloy (SMA) is proposed. Unlike traditional SC-EBFs using a posttensioned mechanism, the proposed EBF utilizes only SMA angles and steel angles, which can vastly simplify the construction of the whole structure. The behavior of the novel SMA-based SC-EBF is studied through numerical models, and its effectiveness is partially verified by the previous testing results. The study is divided into two parts. First, the behavior of the core component, i.e., link beams (LBs), is investigated. The cyclic behavior of the LB indicates that the SMA angles and steel angles can effectively prevent the LB from any damages. The shear key construction can guarantee the centerline-rocking behavior of the LB, greatly decreasing the stress concentration in angles and protecting the corner of the LB. Subsequently, parametric studies on three important design parameters, namely, steel-to-SMA elastic stiffness ratio, prestrain level in bolts, and angle leg length, are conducted via 12 different designs. All three parameters influence the structural stiffness and strength to some extent. The steel-to-SMA stiffness ratio governs the SC and energy dissipation capacity, and a ratio in the range of 0.35-1.5 is recommended in this study. Second, the behavior of a one-story one-bay SMA-based SC-EBF is investigated to illustrate its unique SC performance. The proposed SMA-based SC-EBF presents a promising SC structure alternative, which may simultaneously achieve replaceability, SC capacity, and simple construction.