Resistance of HFI line pipe to external loads

SUMMARY: The present paper addresses issues of pipeline design associated with unintended actions due to external loads or ground movements. These may introduce longitudinal strains in the pipeline owing to combinations of bending moments or curvatures and axial forces. The pipeline resistance for such multi-axial load cases is estimated via analytic equations in isotropic manner using von Mises plasticity. Both tensile and compressive stresses and strains in the pipe section are considered. In the compressive region stability issues as local buckling may dominate. The work hardening behaviour is represented using Hollomon's power law. The equations derived are analyzed in an incremental format. With this a useful tool capable of accurately capturing a large variety of relevant multi-axial loading paths is provided.