Dynamic Finite Element Analysis of Underwater Pipeline under Regular and Irregular Waves

Abstract

Underwater pipeline has been globally utilized during past decades to carry oil and gas from offshore wellheads to coastal facilities due to its cost-effectiveness on the transportation of hydrocarbon resources. It is known that during theinstallation process, pipeline suffers high level of stresses. These stresses acting on pipeline may lead to failure of it and further may require entire replacement of the pipeline due to difficulties of underwater repair. Furthermore, underwater pipeline encounters various type of external loadings originated from wave, current, and sea-bed contact, etc. Therefore, a rigorous analysis on pipeline laying procedure which takes account of all the aforementioned conditions is necessary to prevent costly failures. To elucidate the behavior of underwater structures, dynamic nonlinear coupled analysis utilizing catenary element and FEM (Finite Element Method) is performed. In the catenary structure, equilibrium position of itself is determined by subjected tension which is reciprocal with geometry and position. Furthermore, the behavior of catenary is geometrically nonlinear since forces acting on the catenary structure are also dependent on geometry. Due to the consideration of geometric nonlinearity, iteration procedure is required for each time step to obtain the solution which result in high computational cost. In this research, we propose a computationally efficient dynamic ana