Development of a double-stage yielding damper with vertical shear links

• Published in: Engineering structures 2021-11, Vol.246, p.112959, Article 112959
• Main Authors: Keykhosro Kiani, Babak, Hosseini Hashemi, Behrokh
• Format: Article
• Language: English
• Subjects: Damping capacity; Damping ratio; Deformation; Drift; Earthquakes; Eccentrically braced frame; Energy dissipation; Finite element method; Ground motion; Hybrid damper; Links; Mathematical models; Moment-resisting frame; Replaceable link; Seismic activity; Shear; Stiffness; Structural integrity; Viscous damping
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2021.112959

•A hybrid hysteretic damper with a double-stage yielding mechanism is proposed.•The device consists of two replaceable vertical shear links in series located within a moment-resisting frame.•Cyclic response of the hybrid damper is simulated using finite element analysis.•The hybrid damper can provide energy dissipation capacity over a wide range of story drift levels.•The ASCE 41-17 acceptance criterion for shear links may be unreliable in the proposed device. This study proposes a novel hybrid damper called vertical links system with double-stage yielding (VLDY). The VLDY damper consists of two replaceable vertical shear links connected in series, located within a moment-resisting frame (MRF). When the MRF sustains lateral deformation, the minor link yields in shear. The inelastic shear rotation of the minor link increases till the engagement of the lockout mechanism. Thereafter, the inelastic deformation occurs in the major shear link, and the entire system enters the second yielding stage. The minor link can be adjusted to dissipate the input energy in relatively small inter-story drift levels during moderate earthquakes, and the major link maintains the structural integrity under severe earthquake ground motions. A validated nonlinear finite element modeling protocol in ABAQUS/standard was utilized to examine the applicability and cyclic response of the proposed system. The results showed that the VLDY device could provide stable energy dissipation capacity in a wide range of inter-story drift levels ranging from 0.3% to 4%. In addition, the cyclic secant stiffness, energy dissipation capacity, and equivalent viscous damping ratio of the VLDY-equipped frames significantly increased compared with those of the bare frames. Based on the results, a minimum free span-to-depth ratio of 7 has been suggested to ensure the prevention of the steep moment gradient on the story beams.