Seismic Performance Evaluation of High Strength Steel EBFs, with 304L Steel Links under Successive Earthquakes

Abstract

Abstract Successive earthquakes can bring about permanent displacements and a drop in frame resistance in subsequent cycles. Since a method for designing structures under these scenarios has barely been provided in the regulations, this paper examines the seismic performance of Eccentrically Braced Frames (EBFs) in High-Strength Steel (HSS) frames under different seismic sequences. To this end, EBFs with a variety of materials were undergone 16 scenarios with and without a seismic sequence in the Opensees software. Inter-story drift ratio, energy loss by links, maximum rotation ratio in links, as well as bending moment and curvature curves were further reported and compared in sensitive stories under single and consecutive earth-quakes. The results indicated that employing stainless links could reduce the inter-story drift ratio in the middle stories. Moreover, a less increase drift ratio was observed in some HSS frames after the occurrence of successive shocks. The increase in energy loss caused by successive shocks compared to the single shock was 160%, 147%, and 162% in HSS, Stainless Steel (SS), and Carbon Steel (CS) frames, respectively. Therefore, an HSS frame experienced a lower increase energy dissipation while this frame had more energy dissipation than other frames. Regarding curvature and ductility, the links in HSS5 and HSS9 frame had a similar performance to CS9 and CS5 links in their critical stories, except that their resistance was between 4–7% and greater than the ones in CS frames. Furthermore, Stainless steel links increased the rotation capacity of the links between 6 and 40%.