Experimental study on seismic behavior of welded H-section stainless steel beam-columns

Previous studies have shown that structural stainless steel material has significant cyclic hardening characterized by strain amplitude dependence and unsaturation under cyclic loadings, which could have a remarkable impact on the seismic performance of stainless steel structures. Whether the current stainless steel structure design codes based on their static performance can accurately predict the seismic capacities of stainless steel structural members is worth studying. This paper investigates the hysteretic behavior of welded H-section stainless steel members under combined constant compression and uniaxial cyclic bending. A total of 24 specimens were tested, which covered a variety of test variables including stainless steel grade, section slenderness, axial compression ratio and loading history. Residual stresses of the welded H-sections considered in this study were measured. Then, the failure mode, hysteretic response, ductility coefficient and energy dissipation of welded H-section stainless steel beam-columns were fully obtained from the tests. Cyclic hardening was observed at the structural member level in the tests. The effect of loading history on seismic behavior was thoroughly discussed. It was found that various loading histories can obviously influence the strengths and deformation capacities of welded H-section stainless steel beam-columns resulting in their discrete seismic behavior, mainly due to the unsaturated cyclic hardening feature of stainless steels. Moreover, the current design codes including European Code, American Specification, Australia/New Zealand Standard and Chinese Specification underestimate the seismic capacities of welded H-section stainless steel beam-columns.