The geometrical parameters effect on the degree of bending of multiplanar DTKY tubular joint for offshore platforms

The service life of an offshore structure is an important variable to consider in the sustainability of an infrastructure. The service life could be assessed through fatigue assesment of the critical tubular joint considering the hot-spot stress near the weld of the joint. Another important parameter in assessing the fatigue is degree of bending of the joint which represents the stress distribution beneath the thickness. Finite Element Method based analysis makes structure modelling more advanced and detailed for complex structures. In this study, a case of jacket offshore structure tubular joint, DTKY-type, is modelled by using FEM-based software. Stresses in the tubular joint model will be evaluated for axial load acting on the brace members in a tension-compression combination mode. Non-dimensional geometry parameters such as β, γ, and τ are varied to determine their effects on the degree of bending of the joint. The study show that stress distribution could be well obtained at the critical points of the joint and β generally decreases the degree of bending of the joint at the position of saddle and crown. Meanwhile, γ and τ both, generally increases the degree of bending at the saddle and crown positions.