Investigating the Influence of Lower Grade Steel on the Seismic Performance of Yielding Dampers Subjected to Near-Field and Far-Field Earthquakes

Recent earthquake records reveal that near-field ground motions exhibit characteristics that are significantly different from those of far-field earthquakes. Yielding dampers, used as lateral load-resisting systems in steel structures, represent one of the most advanced technologies for mitigating seismic demands. In addition, the application of mild steel with a lower yield stress than conventional structural steel can enhance ductility, improve overall structural performance, and increase the energy dissipation capacity of the system. In this study, the seismic behavior of three steel moment-resisting frames with ۴, ۸, and ۱۲ stories equipped with yielding dampers was examined using nonlinear dynamic time-history analyses. Two different steel grades were considered for the dampers. The results indicate that near-field ground motions tend to excite higher vibration modes, leading to more severe structural responses, particularly in the ۱۲-story frame. Furthermore, the frames incorporating lower-grade steel dampers demonstrated superior seismic performance under both near-field and far-field earthquake records.

Keywords:

Yielding metallic damper , Energy dissipation , Near-field earthquakes , Nonlinear time-history analysis , Lower grade steel