A three-dimensional multilayered pipe beam element: Nonlinear analysis

This paper addresses the behavior of three-dimensional multilayered pipe beams with interlayer slip condition, under general 3-D large displacements, in global riser and pipeline analysis applications. A new finite element model, considering the Timoshenko beam for each element layer, has been formulated and implemented. It comprises axial, bending and torsional degrees-of-freedom, all varying along the length of the element according to discretization using Hermitian functions: constant axial and torsional loadings, and linear bending moments. Transverse shear strains due to bending are included in the formulation by including two generalized constant degrees-of-freedom. Nonlinear contact conditions, together with various friction conditions between the element layers, are also considered. These are accounted in the model through a proper representation of the constitutive relation for the shear stress behavior in the binding material. The element formulation and its numerical capabilities are evaluated by some numerical testing results, which are compared to other numerical or analytical solutions available in the literature. The tests results show that the new element provides a simple yet robust and reliable tool for general multilayered piping analyses.