ABSTRACT
Welded tubular K-joints made of circular hollow sections under fatigue loading are widely used in civil, mechanical and plant engineering. Recently, more and more thick-walled structures with a low chord slenderness have been realized. Unfortunately, the existing design rules (e.g. CIDECT Design Guide 8 or EN 1993-1-9) cover only K-joint geometries with γ = dn0 / (2 · t 0) > 12 or limit the wall thickness to t0 and t 1 ≤ 8 mm. There had been doubts due to a possible deteriorating size effect, if the fatigue strengths derived from the existing test data can also be recommended for tubular K-joints with low chord slendernesses, ranging between 3 ≤ γ ≤ 12. The outcome of two German research projects is presented. In the first already finalized project the fatigue behavior of thick-walled tubular K-joints had been investigated. In the latter still running project the focus is laid on the influence of the weld quality on the fatigue strength of these joints.
