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Vol. 43 (2002) No. 2 August n. 139

Infinitely Long Buried Pipelines Under Bending and Internal Pressure

< Table of Contents for Vol. 43 (2002) No. 2 August n. 139
  • Journal Name: Journal of the International Association for Shell and Spatial Structures (J. IASS)
  • ISSN: (Electronic Version) 1996-9015
  • ISSN: (Print Version) 1028-365X
  • Issue: Vol. 43 (2002) No. 2 August n. 139
  • Pages: 101-114
  • Title: Infinitely Long Buried Pipelines Under Bending and Internal Pressure
  • Author(s): C. J. Gantes and D. S. Gerogianni
  • Keywords: Buried Pipelines, Infinite Length, Bending Moment,Ovalization, Brazier Effect, Internal Pressure.
The bending behavior of long cylinders with deformable cross-sections is associated with a nonlinear phenomenon, called the Brazier effect. The nonlinear response is induced by ovalization of the originally circular cross-section, which, in turn, decreases the moment of inertia and leads to a nonlinear moment-curvature relation. In addition, the deformation of the cross-section increases the axial bending stresses and lowers the structure’s local buckling load. Thus, reliable design of such structures should include consideration of the Brazier effect on two possible failure modes, namely limit point buckling along the moment-curvature diagram or local buckling bifurcation. For buried pipelines ovalization is partly hampered by the surrounding soil, which provides resistance to parts of the pipe cross-section that tend to deform outwards. In this paper approximate analytical expressions for the Brazier limit moment and the local buckling moment are derived, depending on the stiffness of the surrounding soil, modeled with linear radial translational springs. The nonlinear moment-curvature relation is obtained through energy considerations, with an additional term representing the strain energy of the soil springs. Parametric studies describe the effect of different soil types. The effects of finite length and axial force are described in a companion paper.

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