Static performance and design of cold-formed high strength steel rectangular hollow section X-joints

Abstract

Cold-formed high strength steel (CFHSS) X-joints made of square and rectangular hollow sections (SHS and RHS) brace and chord members were investigated in this study. The steel grades of tubular members were S900 and S960 with the nominal 0.2% proof stresses of 900 and 960 MPa, respectively. The authors carried out tests on cold-formed S900 and S960 steel grades RHS X-joints. The test results were used to develop accurate finite element (FE) models in this study. Using the validated FE models, a comprehensive FE parametric study was then performed. The validity ranges of critical geometric parameters were extended beyond the current limits mentioned in international codes and guides. The nominal resistances predicted from existing design rules given in European code and Comité International pour le Développement et ĺEtude de la Construction Tubulaire (CIDECT) were compared with a total of 726 test and FE joint resistances, including 684 numerical data generated in this study. Chord face failure, chord side wall failure and a combination of these two failure modes were reported. It is shown that design rules given in European code and CIDECT are not suitable for the range of cold-formed S900 and S960 steel grades RHS X-joints investigated in this study. Therefore, user-friendly, accurate and reliable design equations are proposed in this study. Moreover, reliability analysis was also performed for the existing and proposed design equations.