L51460 The Effect of Random Seas on Pipeline Stability Vol II Finite Element Modeling of Pipeline Response

Traditional design practices for offshore pipelines attempt to ensure stability along the entire pipeline system. In shallow water, the standard practice requires the burial of pipeline systems resulting in increased construction costs from trenching operations. Present design methodologies for marine pipeline systems generally require only a static-equivalent stability analysis using hydro-dynamic pipe loadings computed from a design wave.

The purpose of this analysis is to develop a finite element method (FEM) formulation that can be utilized for a detailed study of the evolution of pipeline configurations under random wave attack from directional seas. The primary features of the FEM algorithm developed include: 1) the ability to predict the large deflection response of the pipeline; 2) the ability to model nonlinear hydroelastic fluid forces; 3) the ability to independently model cohesive and cohesion-less sediment loads; and 4) the ability to adopt irregular bottom contours. Additional features provided by the finite element method include: 1) flexibility in discretizing the pipeline system; and 2) the ability to model features such as a missing weight coating along any arbitrary portion of the pipeline.