Flambagem vertical de dutos submetidos à aumento de temperatura

Abstract

Pipelines subjected to high temperature and internal pressure develop significant compressive forces due to the restraint to axial deformation provided by the soil. These compressive forces can reach a critical value inducing lateral (snaking) buckling or vertical (upheaval) buckling and compromising the structural integrity of the pipeline. Therefore, the study of pipeline buckling has great practical importance. This work presents an analytical and a finite element model to study the upheaval buckling. Nonlinear beam elements are used in the numerical analysis allowing the consideration of large displacement and rotations. Since buried pipelines subjected to thermal loads present a symmetric unstable buckling, an appropriate path-following algorithm is used to trace the complete equilibrium path of the model, where the safe temperature increase corresponds to the minimum point of the equilibrium path. Perfect and imperfect pipes are considered and the effect of geometrical imperfections is studied.