Pipeline Beam Models Using Stiffness Property Deformation Relations

Abstract

This paper first reviews the large displacement formulation of the soil-beam pipeline interaction problem. It then demonstrates that two methods of integration, namely, one-dimensional integration of section-property-deformation relationships and three-dimensional volume integration, yield the same results for finite element analysis of pipe that does not buckle and for deformation paths of typical settlements, even though the section-property-deformation relationships are, theoretically, nonintegrable. Similar results are demonstrated for a softening material. Based on the fact that the characteristics of section-property-deformation curves that include the effect of wrinkling can be simulated by this latter type curve, it argues that the analyses have established a reliable method of analysis for a pipe that deforms into the local buckling range. It also demonstrates that the effect of softening is to create a localized area in which the curvatures concentrate, that is, a wrinkle forms, while curvatures at other locations decrease. The section-property-deformation relationships used in the solution of the problems are extracted from three-dimensional shell analyses.