Tensile behaviour of welded S700 rectangular hollow section X‐joints

Abstract High‐strength steels (HSS) have higher strength but lower ductility compared to mild steels. A material factor ( C f ) and a 0.8 f u restriction on the material design yield strength ( f y ) are stipulated to reduce the design resistance of welded HSS hollow section joints in the newest version of prEN 1993‐1‐8 (2022), given the low ductility of HSS and a limited number of experiments on welded HSS joints. However, applying the material factor and the yield strength restriction partially eliminates the benefits of using HSS, limiting its competitiveness. Besides, the type of the weld (fillet weld or butt weld), which is not distinguished in the design rules in prEN 1993‐1‐8 (2022), may influence the mechanical behaviour of the joint. Hence, in this paper, a parametric study is carried out based on the validated Gurson‐Tvergaard‐Needleman (GTN) damage model and the validated finite element (FE) model of two X‐joints in literature. The effect of two parameters, the brace width to chord width ratio ( β ) and the weld dimension, on the tensile behaviour of the welded S700 rectangular hollow section (RHS) X‐joint are evaluated. The FE results are compared to the prEN 1993‐1‐8 prediction, and the necessity of C f and the 0.8 f u yield strength restriction is evaluated.