Strength of K-Type of Joint made of S700

Integration of slim floor systems into high strength steel (HSS) trusses with K-joints promotes sustainable construction due to the high strength-to-weight ratio and open space buildings adaptable for different uses. As current design standards such as EN 1993-1-8 inadequately supports the design of HSS truss joints, in this study, two welded K-type joints made of S700 were tested using a scaled-down dimensions and examined numerically by finite element (FE) models. The scaling factors used for determining the dimensions of the downscaled joint were verified by the validated FE models. The tests on two specimens with the different chord lengths were used to define the strength of the HSS joint: which was controlled by either the ultimate strength of the tension bracing or the buckling resistance of the compression bracing. Compared to the joint of the double grade steel S355J2/S420, the results pointed out that the limit load of HSS joint was 70% higher but the joint ductility was decreased by 25% when compared to the joint of double grade steel S355J2/S420. Due to the instability failure of the compression bracing, applying a larger safety factor for the limit load of S700 joint is necessary but additional parametric studies are needed to propose the equations for the joint limit load in design use.The authors are grateful Ruukki Construction Oy for providing the test specimens and for the Department of Mechanical Engineering for enhancing the specimens. The authors are also grateful for the technical team of the laboratory at the Department of Civil Engineering for preparing and performing the experiments