Mechanical behaviour and experimental evaluation of self-centring steel plate shear walls considering frame-expansion effects

The rocking mechanism of self-centring connections can lead to frame expansion, which can cause significant deformation demands on structural members, incompatible displacements among different structural systems, and excessive cracks in concrete slabs. To address this issue, this study proposes a mixed dual lateral force-resisting system composed of a high strength moment-resisting steel frame (HS-MRF) and self-centring steel plate shear walls (SC-SPSWs). The independent response of SC-SPSWs allows for gap formation without interfering with HS-MRF, thus enabling the use of continuous slabs. The paper first discusses a conceptual damage-control design that includes four performance levels, followed by a mechanical and experimental investigation to study the relationships among structural elements and overall responses, energy-dissipating capability, connection response, post-tensioned (PT) element behaviour, and structural repair potential. The results indicate that the proposed analytical model can reasonably predict the force responses of SC-SPSW with rocking bases. The tested frame exhibited stable flag-shaped hysteretic behaviour with no collapse up to 5.0% inter-storey drift. The web plates served as easy-to-replace energy-dissipating elements, and residual drifts remained small, implying that the proposed structure can be repaired easily in the aftermath of a strong seismic event. Rocking behaviour was observed in both beam-to-column connections and column bases. Although frame expansion still occurs and increases the axial force in the beams of the first storey, the main structural elements can be designed to remain elastic.