Seismic response of flag-shaped hysteretic SDOF systems with seismic fuses

Abstract

Flag-shaped (FS) hysteretic systems with seismic fuses have recently been developed for use in high performance seismicresistant structural systems. Their cyclic response is characterized by the re-centering capabilities with enough seismic energy dissipation while seismic fuses only activate in order to protect a FS system and to magnify the dissipation of seismic input energy at very strong ground shaking. To date, analytical studies have been focused on the seismic response of FS singledegree-of-freedom (SDOF) systems without seismic fuses. Hence more extensive analytical investigation of the seismic response of FS systems with seismic fuses is needed because of their unique cyclic response defined by the FS hysteresis, and by the expanded energy dissipation of the seismic fuses. To do this, this research carries out comparative nonlinear time-history analysis of FS and elasto-plastic (EP) SDOF systems. The analysis results of the FS SDOF systems show that 1) ductility demands decrease with increased structural periods, strength ratios, and post-yielding stiffness ratios; 2) the equations of the equivalent damping ratios are mainly dependent on parameters relating to energy dissipation; and 3) the median maximum displacement demands of seismic fuses decrease with increased post-yielding stiffness ratios, strength ratios, and re-centering limits.