Experimental and Numerical Investigation of Geometric SCFs in Internally Ring-Stiffened Tubular KT-Joints of Offshore Structures

Tubular KT-joints are quite common in offshore structural design and despite the crucial role of stress concentration factors (SCFs) in evaluating the fatigue performance of tubular joints. However, the SCF distribution in internally ring-stiffened KT-joints have not been investigated and no design equation is currently available to determine the SCFs for this type of joint. In the present paper, results of experimental and numerical investigations of the SCF distribution in internally ring-stiffened tubular KT-joints are presented. In this research, experimental study has been followed by a set of parametric stress analyses for 118 steel ring-stiffened KT-joints subjected to balanced axial loads. The analysis results are used to present the general remarks on the effect of geometrical parameters on the SCF distribution along the weld toe and to establish a new set of SCF parametric equations for the fatigue design of internally ring-stiffened KT-joints.