Continuum Finite Element Methods to Establish Compressive Strain Limits for Offshore Pipelines in Ice Gouge Environments

Abstract

In the design process for offshore pipelines in ice gouge environments, compressive strain limits provide a basis to assess pipeline mechanical integrity for design load events. A parametric study, using the continuum finite element methods, has been conducted to assess the global pipeline moment-curvature response for displacement-based loading conditions through the post-buckling regime. The purpose of this study was to investigate the accuracy and efficiency of some computational parameters in simulating the stability characteristics of thick pipes. For that, the study used a pipe that has been the subject of a comprehensive and extensive experimental investigation. In specific, the study selected the exact geometric, material, loadings, boundary conditions and operational parameters similar to the BPXA Northstar pipeline system. The numerical analysis examined the effect of element type, mesh density, internal pressure, axial load, end moment, and geometric imperfection mode on the predicted post-buckling response. The analysis demonstrated the importance of element type, mesh density and characteristics of initial geometric imperfections on the post-buckling response of a thick-walled pipeline subject to combine loads. In addition, element performance and solution efficiency was examined.