Study On Out-of-plane Bending Rigidity Of Ring-stiffened Tubular X-joints

Because of the unique advantage, circular tubular joints are widely used in hollow section structure, the tubular X –joint is a typical style joint in single-layer ribbed reticulated spherical shell. Sometiomes we have to strength the simple joints to enhance the strength and stiffness to satisfy the requirement.At present, the research on tubular joints are mainly concentrated on simple tubular joints, and the research results are provide in existing major codes and design guides.While, part of codes suggest the forms of ring stiffeners, and lack of detailed design guidance on the strength and stiffness of ring-stiffened joints.Firstly, based on references of domestic and abroad, the deformation mechanism of X-joints was expounded and the definition of joint rigidity were introduced, meanwhile, the joints in the literature were analyzed to verity the correctness of the finite element analysis.Secondly, taken the practical single-layer spherical shell as background, the tests and the finite element analysis of the typical tubular X-joints were performed, by analyzing the test data and phenomena and relative FEM analysis, the validity and feasibility of experiment and FEM analysis are verified. It lays a foundation for further large numbers of FEM analysis.Finally, the plentiful FEM parameter analysis of the circular X-stiffened joints loaded with out-of-plane were analysed by using ABAQUS, and formula for predicting out-of-plane rigidity is established. Work mainly included:1) Compare the bending rigidity of X-stiffened joints as the stiffeners set at different positions;2) With parameter analysis, the influence of parameter β、γ、τ 、μ、ζ and θ to joint bending rigidity is researched;3) The influence of axial stress of the main pipe and axial force to joint bending rigidity is researched;4) Formula for predicting out-of-plane rigidity is established through multi-variable nonlinear regression analysis.