Effect of proximity of imperfections on buckle interaction in deep subsea pipelines

Karampour, Hassan

doi:10.1016/j.marstruc.2018.02.011

Cited by 45 publications

(21 citation statements)

References 31 publications

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“…As shown in Karampour et al (2013) and Karampour (2018) the lateral buckling depends on the axial forces in the wall thickness that occur as a consequence of the soil reaction to the expansion of the pipeline when subjected to the internal pressure and thermal loading. In this regards, simulating SSI becomes fundamental to realistically predict such conditions that may severely damage the pipeline.…”

Section: Numerical Modelmentioning

confidence: 99%

Soil Structure Interaction Effects on Stability of HP/HT Unburied Subsea Pipelines Using a Probabilistic-Based Approach

Forcellini

Mina

Karampour

2021

Preprint

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Soil structure interaction (SSI) may considerably affect the seismic vulnerability of subsea high pressure/high temperature (HP/HT) pipelines. Numerical simulations are herein proposed to study the effects of soil deformability on failure of an unburied pipeline with D/t = 20, laid on the seabed and resting on a sleeper. OpenSees is used to assess an earthquake scenario imposed on a laterally buckled pipeline by considering the effects of non-linear soil behaviour on the mechanisms that induce damage on the soil-pipeline system. Uncertainties in the case study were considered by applying a probabilistic-based approach and by developing analytical fragility curves that allow estimation of the probability of exceedance of the selected failure criteria.

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Section: Numerical Modelmentioning

confidence: 99%

Soil Structure Interaction Effects on Stability of HP/HT Unburied Subsea Pipelines Using a Probabilistic-Based Approach

Forcellini

Mina

Karampour

2021

Preprint

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“…The equation system (19) will be solved below for two particular choices of boundary conditions: concerning the tranverse displacement, simply-supported conditions will be equally assumed in both cases (as already considered in many previous studies, such as [39,40]), whereas the torsional rotation at the ends of the beam will be either fixed or free. All the subsequent results are applicable, provided that the following condition is fulfilled (which is always the case in practice):…”

Section: Solution Proceduresmentioning

confidence: 99%

Investigation of the Torsional Effects on the Lateral Buckling of a Pipe-Like Beam Resting on the Ground under Axial Compression

Grognec

Nême

Cai

2020

Int. J. Str. Stab. Dyn.

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This paper deals with the lateral buckling behavior of an axially compressed beam interacting with the ground on which it is resting. Such a simple model is supposed to reproduce the same trends as observed during the lateral buckling of offshore pipelines on the seabed. In such practical analyses, the pipe-soil interaction relates the ground to the neutral axis of the pipeline. It is shown that, although such a constraint significantly affects the buckling behavior of the pipeline, it cannot reflect the torsional component of the buckling modes. However, this component is encountered in practice and may further modify the critical loads. Therefore, in this present preliminary study, the interaction between the beam in hand and the surrounding ground is modeled by a connection (a continuous distribution of lateral springs) related to the bottom line of the beam. In this way, the real contact between the soil and the bottom line of a pipe is mimicked, allowing for both flexural and torsional deformations in the buckling response. The problem is investigated analytically using an Euler–Bernoulli beam model with an isotropic linear elastic constitutive law and also an elastic interaction law. Original analytical solutions are derived and compared to numerical results obtained through finite element computations. In comparison with classical solutions (with the connection related to the neutral axis), new types of buckling modes may appear when considering torsional effects, depending on the boundary conditions, with generally much lower critical loads. These first results are certainly representative of some features of the global/localized lateral buckling of offshore pipelines, indicating that torsional effects should also be taken into account in such more comprehensive analyses.

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“…Both the rise in temperature and in internal pressure may lead to longitudinal expansion of the pipeline. This expansion is restrained by the pipe end devices and the seabed, which can lead to the accumulation of effective axial compressive force in the pipe wall [2,3]. Due to the large effective axial force, lateral or upheaval buckling may be triggered.…”

Section: Introductionmentioning

confidence: 99%

“…Simple and closed-form solutions suitable to design were derived for both initial lift-off and the maximum upheaval buckling loads through this analytical model. Karampour and co-workers investigated the interaction between upheaval or lateral buckling [26] and propagation buckling of subsea pipelines [2,27,28] with the consideration of a single imperfection. The collapse of the pipe-wall due to the interaction between lateral buckling and external pressure was studied and buckle interaction envelopes were developed.…”

Section: Introductionmentioning

confidence: 99%

Snap behaviour in the upheaval buckling of subsea pipelines under topographic step imperfection

Wang

Heijden

2020

Marine Structures

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Pipelines exposed to high-temperature and high-pressure (HTHP) with a topographic step imperfection are susceptible to the phenomenon of upheaval buckling potentially leading to a hazard for the structural integrity of the pipeline. To analyse this problem we derive analytical upheaval buckling solutions and obtain the locations of maximum displacement and maximum axial compressive stress. We also analyse the typical post-buckling behaviour and its dependence on step height, axial soil resistance and wall thickness. The difference in behaviour between a pipeline with step imperfection and one with a symmetric prop imperfection is discussed. Our results show that a pipeline with a step imperfection is more prone to upheaval buckling than a perfect pipeline. For sufficiently small step heights the pipeline may suffer a snap-back instability under decreasing thermal loading, raising the possibility of hysteretic snap behaviour under cyclic thermal loading (for instance caused by periodic start-ups and shutdowns). The snap-back buckling disappears for large enough step height and the minimum critical temperature difference decreases with increasing step height and wall thickness or with decreasing axial soil resistance. The maximum compressive stress decreases with increasing step height and axial soil resistance or with decreasing wall thickness. A pipeline with step imperfection is safer than one with a symmetric prop imperfection.

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Effect of proximity of imperfections on buckle interaction in deep subsea pipelines

Cited by 45 publications

References 31 publications

Soil Structure Interaction Effects on Stability of HP/HT Unburied Subsea Pipelines Using a Probabilistic-Based Approach

Soil Structure Interaction Effects on Stability of HP/HT Unburied Subsea Pipelines Using a Probabilistic-Based Approach

Investigation of the Torsional Effects on the Lateral Buckling of a Pipe-Like Beam Resting on the Ground under Axial Compression

Snap behaviour in the upheaval buckling of subsea pipelines under topographic step imperfection

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