Enhanced design and experimental investigation of disc spring‐based self‐centering buckling‐restrained braces with a compounded combination mode

Abstract

AbstractThe disc spring‐based self‐centering energy dissipation (SCED) brace is a high‐capacity resilient structural component, characterized by a flag‐shaped hysteresis curve, which can provide both damping and recentering capacity to a structure. However, the conventional design method for the disc spring‐based SCED brace cannot quantitatively take into account the friction effects induced by combined disc springs, which greatly limits the disc spring size selection and combination mode. To address this issue, the friction effect of the combined springs is quantified using an incremental energy method and then introduced into the existing design method. A fully assembled self‐centering steel buckling‐restrained brace (SC‐SBRB) consisting of an energy dissipation (ED) system and a self‐centering (SC) system is proposed. The SC system employs a combination mode of stacking multi‐section springs in parallel and compounding new and old springs together to provide the desired recentering capacity for the brace; however, it is distinguished by an appreciable ED capacity that is different from the SC devices in previously reported SCED braces. With the use of the energy method for the quantification of the spring friction, the differences between the mechanical properties of a group of old springs in earlier and recent tests were systematically analyzed to check their reliability and serviceability. A series of test procedures were sequentially conducted on a pure BRB brace and a pure SC brace, and then on the full SC‐SBRB. A fatigue test was also performed after the damaged brace was repaired. The experimental results demonstrate that the improved design can provide accurate estimations of the spring friction in the brace design, and that the proposed brace can exhibit a stable and favorable flag‐shaped hysteretic response with negligible residual deformations throughout the loading protocol. The old spring used in the tests was found to have stable and reliable mechanical properties and could be reused in a brace requiring repair after an earthquake.