Abstract
Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength, which are under different conditions, including pure bending and bending combined with internal pressure. Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes. In parametric analysis, a series of parameters, including pipe geometrical dimension, pipe material properties and internal pressure, were selected to study their influences on the critical bending moment, critical compressive stress and critical compressive strain of pipes. Especially the hardening exponent of pipe material was introduced to the parameter analysis by using the Ramberg–Osgood constitutive model. Results showed that geometrical dimensions, material and internal pressure can exert similar effects on the critical bending moment and critical compressive stress, which have different, even reverse effects on the critical compressive strain. Based on these analyses, more accurate design models of critical bending moment and critical compressive stress have been proposed for high-strength pipelines under bending conditions, which provide theoretical methods for high-strength pipeline engineering.
Highlights
Local buckling is an ultimate state of pipelines under complex loading conditions caused by subsidence, earthquake and landslides, etc., in geological hazard zones (Han et al 2012; Shantanu et al 2011)
This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength, which are under different conditions, including pure bending and bending combined with internal pressure
Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes
Summary
Local buckling is an ultimate state of pipelines under complex loading conditions caused by subsidence, earthquake and landslides, etc., in geological hazard zones (Han et al 2012; Shantanu et al 2011). The model in the ABS standard is only applicable for pipes with a diameter/thickness ratio of 10–60, which cannot be used in pipes with larger diameter/ thickness ratio It is limited by practicable materials and ignoring strain hardening effect; the ‘Mohareb–Murray interaction equation’ and model in ABS may overestimate or underestimate the critical bending moment (Nazemi 2009). Plantenma studied the buckling stress of circular cylinders and round tubes under compression conditions (Ahn et al 2016), which are not applicable under bending loading conditions These models mentioned above have not comprehensively considered the critical properties of strain hardening of high-strength pipelines with bending load. Methods were proposed to predict the critical bending moment and critical compressive stress of local buckling of high-strength pipelines under bending load and demonstrated with an application example. The first thing is to establish a proper finite element model to do the parametric analysis
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