Dynamic analysis of risers using a novel multilayered pipe beam element model

• We model bonded and unbonded multilayered pipes in nonlinear dynamic analysis.
• Hydrodynamic loads are properly derived for the new element.
• It provides accurate representation of layered pipes under large displacements.
• Numerical examples show the accuracy and efficiency of the new formulation.

In this paper a recently proposed formulation for the multilayered pipe beam element is extended to dynamic analysis of risers. Derivations of hydrostatic and hydrodynamic loadings due to internal and external fluid acting on each element layer are presented. Mass and damping matrices, associated to each element layer, are properly derived by adding their respective contributions to the expression of the virtual work due to external loading. The finite element implementation allows for the numerical representation of either bonded or unbonded multilayered risers, including small slip effects between layers. A number of numerical examples have been carried out and the results show the accuracy and efficiency of the new element formulation, even in large scale riser analysis. Moreover, we establish a few benchmarks using multilayered pipes and risers.