SEISMIC FRAGILITY ASSESSMENT OF STEEL STRUCTURES WITH HYBRID YEILDING RING DAMPER

Seismic resilience-based design of structures is an emerging field in earthquake engineering. Low-damage structural systems with the ability to reduce the structural and non-structural damages are candidates for these purposes. Among the various proposed low-damage systems, structural steel frames with ring metallic dampers capable of dissipating the seismic input energy in a fuse part through yielding are proved to be acceptable low-damage seismic resisting systems (Mansouri et al., 2016; Andalib et al., 2018). This paper investigates the seismic fragility of steel frames equipped with a recently proposed dual-performance energy dissipating system known as dual-performance ring damper (Moaddab & Tizhoosh, 2018; Zahrai & Cheraghi; 2017, Cheraghi & Zahrai; 2017). The dual performance damper called TRYD (three ring damper) had been developed to absorb and dissipate seismic input energy at different levels of ground motion intensity. Proposed system is composed of a main fuse to dissipate energy at high-level drift demands encountered in severe earthquakes and an auxiliary fuse to control the responses at lower drift demands normally occurred in moderate earthquakes. The hybrid damper is basically a displacement-dependent device which dissipates seismic energy by yielding of outer and inner rings. This paper first develops and compares the fragility curves of 3-, 9- and 20-story steel structures equipped with both common ring damper (Andalib et al., 2018) and TRYD dampers by considering the three Engineering Demand Parameters (EDPs), namely Peak inter-story drift ratio (PIDR), peak floor acceleration (PFA) as well as peak residual inter-story drift ratio (PRIDR) utilizing a large set of strong ground motions composed of 22 records scaled to maximum considered earthquake (MCE) intensity level.

Keywords:

Hybrid , Ring damper , Moderate earthquake , Sever earthquake , Energy dissipation