Investigating the Seismic Performance of Disc Spring-Based Self-Centering Bracing System

Abstract

Reducing residual deformations is crucial for repairing structures post-earthquake. Steel frame structures that are self-centring and equipped with disc springs show promising performance in this area. This study investigates the seismic performance of this innovative system by first correlating the friction and pre-loading force of the disc springs to their yielding stress. The parameters β (energy dissipation) and γ (secondary stiffness) were analysed. To assess these coefficients, diagonal braces with varying β and γ values were incorporated into a single-storey, single-bay frame. These models underwent quasi-static loading and were validated using experimental data. The results revealed that three braces with coefficient pairs of (β, γ) = (1, 1.2), (1, 1.6), and (1, 2) achieved maximum energy dissipation with nearly zero residual deformations. Further investigation involved designing nine structural models of 3-, 6-, and 9-storey buildings equipped with disc spring-based, self-centring bracing systems that included friction plates. Additionally, three special Chevron-braced steel frame models of 3-, 6-, and 9-storeys were designed for comparison with the self-centring frames. Utilizing OpenSees software and the TCL programming language, all twelve models were analysed through Incremental Dynamic Analysis subjected to specified ground motion records. A fragility curve for each case was derived. The results demonstrated that the self-centring frame with coefficients of β = 1.0 and γ = 1.2 showed improvements of 118% and 504% in collapse capacity and residual deformation control, respectively, compared to the equivalent Chevron-braced frame, with only a 17% increase in weight.