The bending stress variation along the subsea route of two highly pressurized pipelines is identified with the aid of a seventh order finite element model. The equation governing geometric nonlinear pipeline deformations is derived from first principles. By casting the equation of flexure into a quasi-linear stiffness and a nonlinear load component the complexity of form is significantly reduced. A 4 d.o.f, nodal formulation enables a direct evaluation of the nonlinear load vector, using element average derivative functions. A successive overrelaxation method is adopted for the simultaneous identification of the pipeline-seabed contact points and the vertical displacements at the interim spans. Nonlinear axial force calculations, due to horizontal motion restraint at the boundary points, are further carried out. Pipe bending along a hypothetical crossing is investigated in order to test the efficiency of the proposed numerical scheme. The model is subsequently applied to the bending stress analysis for the installation phase of two submarine pipelines connecting the island of Revithoussa with the Aghia Triada peninsula in Greece. The final in-situ corrected seabed profiles prior to pipeline launching are adopted in all relevant calculations. A thorough examination of the effect of surcharge load variation upon the critical stress and pipe lifting during pressurization is additionally carried out.
Geometric nonlinear modelling of submarine pipeline crossings
International Journal of Offshore and Polar Engineering ; 8 , 4 ; 292-302
1998
11 Seiten, 15 Quellen
Aufsatz (Zeitschrift)
Englisch
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