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


The Effects of Finite Length and Axial Force for Buried Pipelines in Bending

< 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: 115-123
  • Title: The Effects of Finite Length and Axial Force for Buried Pipelines in Bending
  • Author(s): C. J. Gantes and D. S. Gerogianni
  • Keywords: Buried Pipelines, Axial Force, Bending Moment, Ovalization, Brazier Effect, Finite Length.
Abstract
In the previous companion paper it was explained how the bending behavior of long cylinders with deformable cross-sections is associated with a nonlinear phenomenon, called the Brazier effect. Nonlinearity is induced by ovalization of the originally circular cross-section, which 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. This effect was treated analytically for the case of buried pipelines, where ovalization is partly hampered by the surrounding soil. Approximate analytical expressions for the Brazier limit moment and the local buckling moment of infinitely long buried pipelines under bending and internal pressure were derived, depending on the stiffness of the surrounding soil, modeled with linear radial translational springs. In this paper, the above approach is extended for the cases of infinitely long buried pipelines under bending and axial force, as well as for buried pipelines of finite length. The nonlinear moment-curvature relation is again 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.

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