A Material Model for Pipeline Steels

Experience has shown that the pipe steel used in the Trans-Alaska Pipeline System has complex properties that must be taken into account in making safety assessments of the pipe. To obtain a better understanding of the steel behavior, a detailed test program has recently been undertaken. The test results have been used to develop a nonlinear model of the steel for use in stress and deformation analysis of the pipeline. This paper first outlines the model, and shows that it captures important aspects of the steel behavior, including progressive yielding and anisotropy. The paper then shows how the values of the model parameters can be calculated from experimental stress-strain data, and how the model can be used for the analysis of pressurized pipelines, accounting for interaction between hoop and longitudinal stress. The theory is based on von Mises yield and the Mroz plasticity model.