Study on the Hot Spot Stress Distribution at Multi-Planar Tubular KK Joints Under Axial Loads

The Hot Spot Stress (HSS) distribution around welded tubular joints in truss legs is essential information for the fatigue assessment of jack-up platforms. Both Finite Element (FE) analysis and model test were carried out on a multi-planar tubular KK joints under asymmetric axial loads in our research. The study shows that the HSS distribution around welded joints is different from common K or T joints, and the maximum HSS appears between crown and saddle on the chord surface at the chord-brace intersection. Moreover, some sensitive factors which influence the locations of the maximum HSS were investigated by FEA in this paper. The analysis results are useful for the optimal structure designing and crack initial prediction of the offshore jack-up platforms legs.