TABLE OF CONTENTS Long cylindrical tubes and pipes under axial compression will usually bend, behaving as beam columns. Shell-type localized buckling occurs mainly when the structure is restrained from lateral movement. This, for example, is the case for a pipeline buried in a trench (Figure 11.1) or resting on a deformable foundation. Compression can be caused by the passage of hot hydrocarbons carried from the well to a central gathering point by buried flowlines in offshore operations [11.1]. Foundation motion caused by fault movement, landslides, ground subsidence, permafrost melting, or soil liquefaction can also result in severe compression of the lines [11.2 11.6]. Both loading scenarios can impose compressive strains high enough to result in shell-type buckling. In most onshore and offshore pipeline operations, diameter-to-thickness ratios ( D/t) and steel grades are such that buckling occurs in the plastic range. In this chapter, the main features of plastic buckling under axial compression are first illustrated experimentally. The formulation for predicting the onset of plastic wrinkling is then developed, followed by a study of how wrinkles grow, localize and lead to collapse.
Unlike elastic shell buckling in which collapse is sudden and catastrophic, plastic buckling failure is preceded by a cascade of events, where the first instability and collapse can be separated by average strains of 1 5%. The behavior is summarized schematically in the axial stress-shortening response of a...
