Experimental and Numerical Study of Cold-Formed High-Strength Steel CHS X-Joints

Abstract

In this study, the behavior of high-strength steel circular hollow section (CHS) X-joints was systematically investigated by experimental and test-validated numerical analysis. A total of nine CHS X-joints fabricated from cold-formed tubes were tested under axial compression. The key test variables included different grades of steels and geometrical configuration of the joint. The joint strength observed was mostly governed by the widely accepted 3% indentation criteria before reaching the peak strength. All of the high-strength steel X-joints tested in this study exceeded the nominal strength with sufficient margin found in the Eurocode. Supplemental numerical results also corroborated this experimental observation, implying that the joint strength reduction factor of 0.8, which currently used for high-strength steels in the Eurocode, may be too conservative and needs to be re-examined. Overall, the experimental and supplemental numerical results of this study indicated that high-strength steel CHS X-joints show satisfactory performance, just slightly inferior to ordinary steels, in terms of serviceability, ultimate strength and ductility, even when the yield strength of steel is as high as 800 MPa.