Free vibrations of free spanning offshore pipelines

Vedeld, Knut; Sollund, Håvar A.; Hellesland, Jostein

doi:10.1016/j.engstruct.2013.04.013

Cited by 38 publications

(19 citation statements)

References 10 publications

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“…If a pipeline is deformed statically, the curved system responds differently to dynamic loading than a perfectly straight configuration. Most notably, the curvature will couple axial and transverse degrees of freedom, which has a stiffening effect, increasing both the modal response frequency and the associated modal stresses (Fyrileiv and Mørk, 2002;Vedeld et al, 2013). In cases where the deflection is more extreme, the first symmetric mode shape becomes suppressed, and the first anti-symmetric mode attains the lowest frequency (Fyrileiv and Mørk, 2002;Vedeld et al, 2013).…”

Section: Mathematical Modelmentioning

confidence: 97%

“…Hobbs (1986) solved for the frequency of a free span resting on soil at each end, where the soil was modeled as a linearly elastic foundation. Fyrileiv and Mørk (2002) expanded on the theory of Hobbs by including an approximation for the effect of axial forces, based on work by Hetenyi (1946), and also considered the stiffening effect of static deflections (Fyrileiv and Mørk, 2002;Vedeld et al, 2013). Fyrileiv and Mørk (2002) adjusted their approximation by curve fitting to the results of a large number of FE analyses.…”

Section: Introductionmentioning

confidence: 99%

“…Since the number of analyses is considerable, it is desirable to have a fast and accurate way to predict such modal response parameters. Generally, the modal response may be determined to any desired accuracy using finite element (FE) software or appropriate semi-analytical models Vedeld et al, 2013). On the other hand, FE analyses are cumbersome and time consuming to perform parametrically and semianalytical methods require time and thorough verification to implement.…”

Section: Introductionmentioning

confidence: 99%

“…The solutions are developed by initially spanning the solution space in non-dimensional parameters determined using the Buckingham Pi theorem (Logan, 1997;Palmer, 2008). A highly accurate semi-analytical method (Vedeld et al, 2013) is applied to create response surfaces in the dimensionless solution space, and various surface fitting techniques are applied to create simple closed-form analytical expressions for these response surfaces. Extensive parametric comparisons are made between the novel analytical solutions and solutions obtained with the semi-empirical formulae of Fyrileiv and Mørk (2002).…”

Section: Introductionmentioning

confidence: 99%

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Modal response of short pipeline spans on partial elastic foundations

2015

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Section: Mathematical Modelmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modal response of short pipeline spans on partial elastic foundations

2015

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“…Dai et al (2013) investigated the CF VIV of a hinged-hinged pipe conveying fluid by considering the internal fluid velocities ranging from the subcritical to the supercritical regions. Vedeld et al (2013) introduced a semianalytical model for the dynamics analysis of pipelines with free spans, and found that Euler-Bernoulli beam theory is sufficient with regard to pipeline free span modeling.…”

Section: Introductionmentioning

confidence: 99%

Study on pure IL VIV of a free spanning pipeline under general boundary conditions

et al. 2017

China Ocean Eng

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Pipeline spans may occur due to natural seabed irregularities or local scour of bed sediment. The pure in-line (IL) vortex-induced vibrations (VIV) analysis of the free spans is an important subject for design of pipeline in uneven seabed. The main objective of this paper is to analyze the characteristics of pure IL VIV of a free spanning pipeline under general boundary conditions. An IL wake oscillator model which can describe the coupling of pipeline structure and fluctuating drag is introduced and employed. The coupled partial differential equations of structure and wake are transformed into a set of ordinary differential equations using two-mode Galerkin method. Some case studies are presented and thoroughly discussed in order to investigate the effects of internal fluid, axial force and boundary conditions on the pure IL VIV.

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Impact of local site conditions on seismic performance of free‐spanning submarine pipelines: Underwater shaking table tests and numerical simulations

Pan,

Li,

et al. 2024

Earthq Engng Struct Dyn

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Local site conditions may pose a significant influence on the seismic responses of submarine pipelines by altering both the offshore motion propagation and soil‐structure interaction (SSI). This paper aims to provide an in‐depth understanding of the influence regularity of local site conditions on the seismic performance of free‐spanning submarine pipelines (FSSPs). For this purpose, a suite of underwater shaking table tests were performed to investigate the seismic responses of FSSP subjected to the offshore spatial motions at three site categories. Response comparison factor () is defined to quantify the structural response discrepancies caused by the seismic inputs at different sites. The test results indicate that responses of the studied model FSSP gradually increase as spatial offshore motions at softer soil sites are employed as inputs; and the values of vary with a maximum magnitude of up to 40%–60% for different response indices when the site soil changes from fine sand to clay. Subsequently, the corresponding numerical simulations are carried out to reproduce the seismic responses of the test model. The experimental and numerical results meet a good agreement, indicating that the developed numerical modeling method can accurately predict the seismic responses of FSSPs. Following this verified modeling method and using the p‐y approach to address the SSI effect, fragility surfaces of the studied FSSP are derived in terms of PGA and site parameter (shear‐wave velocity in the top 30 m of the soil profile) via probabilistic seismic demand analyses. The impact of local site conditions on the seismic performance of the FSSP is quantitatively examined by comparing the fragility curves corresponding to various . Furthermore, a fast seismic damage assessment method is proposed for efficiently evaluating the performance of FSSPs buried in various offshore soil conditions. This approach proves beneficial for designers and decision‐makers, enabling accurate estimation of seismic damage and facilitating the implementation of post‐earthquake maintenance measures for FSSPs.

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Free vibrations of free spanning offshore pipelines

Cited by 38 publications

References 10 publications

Modal response of short pipeline spans on partial elastic foundations

Modal response of short pipeline spans on partial elastic foundations

Study on pure IL VIV of a free spanning pipeline under general boundary conditions

Impact of local site conditions on seismic performance of free‐spanning submarine pipelines: Underwater shaking table tests and numerical simulations

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