Classification and ultimate capacity of duplex stainless steel H-section under cyclic loading

Abstract

Stainless steel materials are high ductility and strain hardening under cyclic loading, which is promising in seismic design. However, the current European stainless steel structure design code prEN 1993-1-4(EC3) ignores this favorable effect in the cross-section classification, as well as the lack of prediction formulas for the ultimate capacity of H-section under cyclic loading. In this paper, parametric analysis was carried out for H-section to extend the database based on the existing test results after calibration of the finite element model. The cross-section classification criteria of duplex stainless steel beams and beam-columns around major-axis under cyclic loading were investigated, and the EC3 classification of stainless steel H-section was evaluated. The predicted results for EC3 are conservative due to not considering the constraints of the cross-section component plates and the favorable conditions for the material strengthening of stainless steel under cyclic loading. Based on this, classification criteria for stainless steel H-section under cyclic loading were proposed and summarized. Subsequently, the method of calculating the ultimate capacity methods under cyclic loading suggested by EC3, Chen and Zhou et al. were evaluated. The results show that EC3 is on the conservative side, with actual results being generally 1.5 times higher than the predictions. In contrast, Chen and Zhou et al.'s method is on the unsafe side of the prediction. Finally, improvement suggestions are given for EC3 and the continuous strength method by considering the over-strength factor under cyclic loading, respectively, with results exhibiting high accuracy.