Experimental and numerical investigations of hybrid high strength steel welded T-section stub columns with Q690 flange and Q460 web

Comprehensive experimental and numerical investigations on mechanical properties of Q690 and Q460 high strength steel (HSS) sections and stub column behaviour of the 14 hybrid HSS welded T-section stub column specimens are presented in this paper. A total of six coupon specimens were longitudinally and transversely machined from HSS Q690 and Q460 steel parent plates respectively. Furthermore, initial local geometric imperfections measurements were also carried out. In parallel with the experimental investigation on stub column behaviour, extensive numerical studies were carried out by developing finite element (FE) models to replicate the experimental tests results. The validation of the FE models was confirmed against the obtained experimental data. To supplement the experimental data, validated FE models were used in the parametric studies, by which numerical specimens with a larger range of cross-section dimensions can be generated. Subsequently, cross-section classification slenderness limits for outstand plate elements under compressive load set out in structural steel design codes of EN 1993-1-12, ANSI/AISC 360-16, AS 4100 were evaluated against the experimental and numerical data. In addition to the design codes, design methods such as direct strength method (DSM) and continuous strength method (CSM) were also assessed to evaluate the applicability and suitability for hybrid HSS welded T-section stub columns. It was found that the current codified slenderness limits in EN 1993-1-12, ANSI/AISC 360-16 as well as AS 4100 for slender/non-slender outstand flat elements can generally be adopted for hybrid HSS welded T-section under compression. CSM provide under-estimated compressive resistance in comparison to the design codes and DSM for slender sections.