Resilient self-centering viscous-based bracing with SMA and friction springs: Multi-objective control of displacement and acceleration – an analytical study

Self-Centering Piston-Based Braced Frames (SC-PBBFs) are designed to curtail structural damage under severe ground motions. The self-centering mechanism in this bracing mitigates structural damage during an earthquake, thereby reducing post-earthquake repair costs and contributing to seismic resilience. However, non-structural components, particularly those sensitive to floor acceleration, remain vulnerable, resulting in prolonged functional recovery times. This paper aims to address this limitation by introducing a novel structural archetype, the Self-Centering Viscous-Based Braced Frame (SC-VBBF), which integrates superelastic shape memory alloy (SMA) bars, viscous dampers (VDs), and friction springs (FSs). A streamlined analytical approach relies on the strength decoupling of VD from other components using a λ factor to design SC-VBBFs. To evaluate the effectiveness of the hybrid brace, a set of 4-, 8-, and 12-story archetypes equipped with SC-PBBs and SC-VBBFs are simulated in OpenSees and analyzed under various earthquake types, including crustal, subcrustal, and subduction events. The results demonstrate the superior performance of the SC-VBBF with λ ≤ 0.5 system compared to SC-PBBFs in mitigating floor accelerations under design-level earthquakes and improving seismic resilience.