Tension capacity of reinforced K-joint connecting rectangular tubes and plate

The research deals with tension capacity of an axially loaded K-joint, which is isolated from a truss-floor where it connects rectangular tubular braces to plate chord and division plate. The study comprises experimental and numerical parts. Experiments were for validating the finite element (FE) modelling used for analysing with 1080 FE models the sensitivity of joint tension capacity to dimensions of its members and a brace inclination angle. The determining criterion for tension failure was 5 % averaged equivalent plastic strain (EPS) within a control volume (CV) that included brace side walls along welds. An experimentally validated width of CV was 0.2 times brace wall thickness. Among 1080 FE models, brace tension failure occurred if ratio of thicknesses between a brace wall and chord plate is smaller than 0.5 and a division plate is at least twice thicker than the brace wall. The brace and division plate should be wider than 25 % and 35 % of chord width, respectively. These ratios guide to select braces and a division plate appropriately for a truss chord. Braces angled at 45° to chord gave the smallest tension capacity, and an angle of 30° led to a greater capacity than the 60° angle. Tension capacities were compared to the nominal joint capacities derived from the new Eurocode 1993-1-8:2024. On average, numerical results were 20 % greater than code-based capacities, but in some cases, the code gave capacities that were 93 % of numerical values. Modifications made for the Eurocode equations kept code-based capacities conservative regarding the FE results. • Sensitivity of K-joint tension capacity based on 1080 automatically created FE models. • The size of the control volume of strain failure criterion was validated experimentally. • Brace inclination angle to a plate chord affects the joint tension capacity. • Brace tension failure occurs with certain ratios of member sizes to chord dimensions. • Unsafety of code capacities compared to FE results removed by modifying code formulas.