Performance enhancement of low-prestressed self-centering braces: An experimental study

Abstract

Self-centering (SC) braces have demonstrated efficacy in controlling structural peak and residual deformations after earthquakes; however, their widespread adoption has been obstructed by high prestressing force demands. To address this limitation, a Low-Prestressed Self-Centering (LPSC) brace was developed, featuring a tension-only energy-dissipative system formed by integrating a ratchet component and steel dissipators in series. This configuration minimizes resistance to self-centering system during brace unloading, enabling effective self-centering under low prestress. Although the mechanism of this brace has been verified, two critical challenges remain in its seismic performance: limited cumulative energy-dissipative capacity and considerable free-travel (the slip distance required for brace to develop stable stiffness) observed in its hysteresis behavior. This study enhanced the performance of the LPSC brace by conducting elongation tests on steel dissipators and parametric evaluations of the ratchet component, with an emphasis on increasing cumulative energy-dissipative capacity and stabilizing hysteretic behavior. These component-level enhancement were subsequently validated through comprehensive full-scale brace tests. Stainless steel (S31603) was identified as an alternative to conventional Q235 steel for the steel dissipator, with elongation tests demonstrating that S31603 achieves elongation capacities over three times those of Q235 steel. Furthermore, parametric tests on the ratchet component revealed that reducing chuck size and increasing spring prestress effectively minimize free-travel during cyclic loading. Comprehensive full-scale brace tests demonstrated that the enhanced LPSC brace achieves a cumulative energy-dissipative capacity with a twofold increase compared to the original design, with free-travel reduced to 1/4 of the original configuration. These findings confirm that the enhanced LPSC brace addresses critical limitations of earlier designs, offering improved energy dissipation and seismic reliability. The proposed enhancements establish the LPSC brace as a viable and efficient solution for practical applications in resilient structural systems.