A post-tensioned self-centering yielding brace system: development and performance-based seismic analysis

Recent seismic events demonstrated that excessive post-earthquake residual drifts might result in high repair costs, temporary interruption of building functions due to required repairs, or even in the total destruction of the buildings. As such, minimizing residual drifts is a critical step in facilitating the rehabilitation of a building after an earthquake. To this end, a highly resilient post-tensioned self-centering yielding brace system (PT-SCYBS) has been introduced and studied. PT-SCYBS is envisioned to be implemented in new or existing diagonally braced frame systems. This system relies on the inherent self-centering behaviour of post-tensioned wires along with the yielding behaviour of the steel bars to provide a flag-shaped hysteretic response. This paper presents a comparative study of the PT-SCYBS frames, moment-resisting frames (MRFs), and buckling restrained braced frames (BRBFs) using the results from a series of nonlinear dynamic analyses. Then, a comprehensive comparative seismic performance assessment of the PT-SCYBS buildings and the reference MRF and BRBF buildings has been conducted using the FEMA P58 methodology implemented in the PACT software. The results show that the PT-SCYBSs have lower residual drifts than the reference buildings, resulting in significant reductions in the repair costs/time and casualties, and exhibit improved seismic performance.