Finite element stress analysis of unilaterally supported submarine pipelines

A linear-elastic finite element model is applied to the solution of stress analysis problems involving submarine pipelines freely resting upon irregular seabed profiles. The structural matrix system is derived on an equal length element assembly basis, thus enabling the formulation of a particularly compact 3 d.f nodal equation algorithm. The unknown contact points and the pipeline deformations are simultaneously identified with the aid of a successive over-relaxation solution algorithm. Tensions generated due to mean internal and external fluid pressure differences are taken into account. Surcharge imposition proves beneficial for the control of critical pipeline over-stressing and upward lift during pressurization. Case study details of the installation design for a subsea dual pipeline crossing are included. A FORTRAN subroutine is provided for illustration purposes of the proposed numerical technique. Copyright (C) 1996 Elsevier Science Ltd.