Testing, numerical modelling and design of S960 ultra-high strength steel welded T-section stub columns

Ultra-high strength steel (UHSS) has been successfully gaining attention in the construction field because of its superior mechanical properties (e.g., a higher strength-to-weight ratio). However, the practical applications of 960 MPa UHSS remain limited, to some extent, because of the absence of the relevant design codes. To address this issue, this paper investigates the compressive characteristics of S960 UHSS welded T-section stub columns experimentally and numerically. The initial local geometric imperfection measurements and stub column tests were then carried out on all 10 specimens. Beyond the experimental work, numerical modelling for UHSS welded T-section stub columns was conducted virtually by means of finite element (FE) models. The validated FE models were subsequently utilized in the parametric analysis to generate a comprehensive database to supplement the test results, which are used to evaluate the applicability of the relevant design clauses in European, American and Australian codes. The results of the investigations showed that (i) the codified slenderness limits in the three design codes are applicable to the S960 UHSS welded T-section and (ii) the design rules specified in all the three codes can generally provide accurate and consistent predictions of the compression resistance for S960 UHSS T-section stub columns, but still yield some conservative results for slender sections.