Finite Element Modeling of Collapse Propagation In Offshore Pipeline

In the design of marine pipelines, like other thin-walled structures, structural stability plays major role. Generally, two kinds of instabilities, namely global buckling and local buckling (collapse) may occur in marine pipelines. However, for deep water pipelines in addition to occurrence of collapse, another concern is the potential occurrence of propagating of this collapse along the pipe due to high external pressure. In the present study, details of 2-D and 3-D finite element modeling for collapse propagation simulation are outlined. In order to verify the accuracy and validity of the finite element modeling, the numerical results, obtained from nonlinear finite element analyses for several pipe samples have been compared with the experimental results. These proposed 2-D and 3-D modeling methods are easily applicable. Also, the comparison shows that the results of these methods have very close agreement with the experimental behaviour. Using nominal geometric properties, finding minimum required imperfections to eliminate bifurcation points and using corrected Ramberg-Osgood material behaviour for steel pipe are the main characteristics of the present 3-D method. The study shows that this method gives more appropriate results than the previous proposed method by Toscano et al. (2002).