Abstract
The analysis of local buckling behaviors in urban heated water steel pipelines currently relies on empirical formulas derived from axial buckling load principles within elastic thin shell theory.* There is a pressing need to explore more rational elastoplastic failure criteria for pipelines subjected to temperature loads and to propose improved methods for designing anti-buckling wall thickness. In this study, we investigate the local buckling behavior of large-diameter steel pipelines with geometric imperfections under axial compressive loads through a combination of full-scale experiments and numerical simulations. Utilizing a validated numerical algorithm for shell buckling analysis, we develop a refined three-dimensional numerical model integrating solid elements to simulate soil and shell elements to represent the pipeline. This model enables the examination of local buckling behavior in buried pipelines with initial geometric imperfections under temperature loads. Through a parametric 3D numerical model, we systematically explore the quantitative impacts of pipeline geometry parameters (such as pipe diameter and wall thickness), initial imperfection size (including defect width and out-of-straightness), and in-service loads (such as internal pressure and temperature) on the thermal buckling behavior of buried pipelines. We propose empirical formulas to predict peak plastic strain and deformation in the pipe. The findings presented herein furnish theoretical underpinnings for wall thickness design and safety assessment of buried large-diameter steel pipes.
