Effect of chord compression on the ultimate strength of ring-stiffened tube-gusset KT-type and X-type joints

The mechnaical properties of ring-stiffened tube-gusset joints have elicited increasing attention from designers because of their reasonable stress distribution. However, research on the effect of chord compression on the ultimate strength of ringstiffened tube-gusset joints remains insufficient. Accordingly, this study proposes a design formula to address this deficit. Two typical ring-stiffened tube-gusset joints, i.e. tube-gusset KT-type joints stiffened by 1/4 ring plates and tube-gusset X-type joints stiffened by ring plates, are considered. Firstly, full-scale tests are conducted. The ultimate strengths of the KT- and X-joints are obtained under different chord compressions. Secondly, a parametric study is performed to discuss the effect of chord axial pressure basing on validated finite element modes. Then, the current relevant design formulae are adopted. The test and finite element analysis results indicates that the current design equations are not always effective under all conditions. At last, one modified design equation is proposed for KT-joints. The proposed method can provide improved prediction of the strength of KT-joint.