Stress Concentration Factors in Tubular K-Joints Under Combined Loadings

A numerical method of stress concentration factors (SCFs) in tubular K-joints under combined loadings was proposed, and the loading effects on SCFs were investigated by using this method. Since it couldn’t present the state of stress concentration very well if the displacements were used as the boundary conditions, the load boundary conditions were selected to analyze the stress distribution of the tubular K-joints. In view of the disadvantages of the superposition of stress distributions from each uniaxial loading mode, an alternative method for the calculation of the hot spot stress under combined loadings was provided. In this method, three basic types of basic loadings namely, axial loading, in-plane and out-of-plane bending moments were applied to the tubular joints simultaneously by virtue of the submodeling technique in ANSYS system. Then the stress distributions along the intersection of tubular K-joints under combined loadings were developed directly, and the hot spot stresses were obtained through extrapolation. Finally, according to parametric study, the loading effects of ice thickness and drift direction on SCF distributions and values were studied through this method. The investigation provides the theoretical basis for determining SCF in tubular K-joints under different load cases in evaluating the ice-induced fatigue of offshore platforms, and has very important engineering application value.