Classification and ultimate capacity of stainless steel CHS under cyclic loading

In order to investigate the cross-section classification criteria and ultimate capacity of stainless steel circular hollow section (CHS) under cyclic loading, this study focuses on the austenitic S30408 and duplex S22053 CHS members by calibrating finite element models using recent experimental results, which were subsequently used in a comprehensive parametric study to extend the dataset. The differences between the cyclic and monotonic loading behavior of stainless steel CHS members were discussed. It was found that when the diameter-to-thickness ratio is small, the ultimate capacity under cyclic loading is significantly higher than that under monotonic loading due to the cyclic hardening effect of material, although the ductility is lower in cyclic loading than in monotonic loading. The applicability of the current European stainless steel structural design code prEN 1993-1-4 for the cross-section classification criteria of stainless steel CHS members was evaluated. The results indicated that the classification limits are conservative, and based on this, recommended classification limits were proposed. Finally, the applicability of prEN 1993-1-4 and the continuous strength method for predicting the ultimate capacity of stainless steel CHS members under cyclic loading was assessed. Both prediction methods were found to be conservative. Consequently, an over-strength factor was introduced to account for the cyclic strengthening effect, and an improved calculation method for prEN 1993-1-4 was proposed. The suggested improved method demonstrates higher accuracy and consistency. • Classification criteria for stainless steel CHS under cyclic loading was studies. • Evaluated the cross-section classification criteria and ultimate capacity according to EC3 design codes. • New cross-section classification criterion for CHS under cyclic loading was proposed. • Modified method for calculating the ultimate capacity of stainless steel CHS members and shown to offer improved design accuracy.