ANALYTICAL FORMULAE FOR THE LATERAL BUCKLING BEHAVIOUR OF PIPELINES INSTALLED WITH RESIDUAL CURVATURE

Residual curvature installation of subsea pipelines has become a popular method for lateral buckling management because of its low-cost implementation and high reliability. The method is foreseen to remain attractive due to the positive operational feedback made available to the public domain. On the design methods, previous research has predicted the behaviour of pipelines installed with residual curvature mainly via finite element analysis (FEA). These analyses include lateral buckling, installation, reeling etc. Further to this, Teigen and Ibrahim have put an effort into quantifying design uncertainties using structural reliability analysis (SRA). Analytical approaches have also been explored, such as pipeline rolling, and other effects during pipeline installation. However, there is little published work on analytical approaches for the lateral buckling behaviour. Therefore, this paper suggests analytical formulations for the lateral buckling behaviour of pipelines installed with residual curvature. For predicting the critical buckling force, the Palmer formulation was used as a basis. For predicting the pipeline integrity post buckling while accounting for non-linear effects and residual plasticity in the system, the formulation is derived using a combination of dimensional analysis, regression analysis and a modified Hobbs formulation. The resulting analytical formulation is calibrated to a database of finite element solutions. The suggested approach is assessed for a configuration that applies model parameters based on the Skuld pipeline. A validation has been performed and the errors have been assessed to verify the suitability of the proposed analytical approach.