Experimental investigation of structural behavior of 316L stainless steel and carbon steel slit dampers

To expand the range of applications for stainless steel in building structures, previous studies have tested the seismic resistance of structural elements and members using a variety of types of stainless steel. Steel slit dampers have been designed and installed for seismic retrofits of building structures. In this study, hysteresis behaviors of austenitic stainless steel (STS316L) and carbon steel (SS275) slit dampers were investigated and compared to demonstrate the excellent seismic performance of stainless-steel slit dampers. Monotonic and cyclic material tests for STS316L and carbon steel were conducted. STS316L had the best seismic performance, with much greater ductility, strength enhancement and cyclic hardening effect than SS275. STS316L with increased nickel (Ni) and reduced chromium (Cr) contents transformed to exhibit twinning induced plasticity (TWIT) steel after yielding under cyclic loading and thus possesses a more stable austenitic microstructure than SS275 and STS304. Loading experiments with STS316L and SS275 slit dampers were performed according to six loading protocols. The fracture shapes, stiffness, ductility, yield strength and energy dissipation capacity also were compared. STS316L dampers provided greater secondary stiffness, ultimate strength, number of cycles and energy dissipation capacity than SS275 dampers. The ultimate strength and normalized energy dissipation capacity of the STS316L specimens were on average 1.53 times and 4.84 times larger, respectively, than those of the SS275 specimens thanks to excellent ductility and strong cyclic hardening effects at the material level. This study proved that the performance of austenitic stainless steel STS316L as a seismic material and slit damper is superior to those of mild carbon steel SS275 and austenitic stainless steel STS304.