The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform

Pe Damsleth - One of the best experts on this subject based on the ideXlab platform.

  • a finite element model for in situ behavior of offshore pipelines on uneven Seabed and its application to on bottom stability
    The Proceedings of the ... International Offshore and Polar Engineering Conference, 1999
    Co-Authors: Jo A Ose, Pe R Nystrom, Pe Damsleth
    Abstract:

    This paper presents a Finite Element (FE) model for simulation of the in-situ behavior of offshore pipelines laid on a 3-D Seabed, with focus on on-bottom stability, The Seabed is produced in the FE model based on 3-D survey data (Digital Terrain Model, DTM) from the area where the pipeline is to be installed. In the in-place analysis part of the model, the load history of laying, flooding, pressure testing, and operation is simulated. In the on-bottom stability analysis part, wave and current loading is applied as a restart of the relevant loading condition and the dynamic behavior of the pipeline is investigated. The importance of simulating the true load history before applying the hydrodynamic loads is that it gives a more correct initial pipe configuration and force distribution prior to the stability analysis. A matter that complicates the on-bottom stability analysis of pipelines on a 3-D Seabed is the fact that the hydrodynamic coefficients among other things are dependent on the Seabed proximity. This problem has been solved in the FE model by calculating the gaps between the pipe and the Seabed at multiple, equally spaced points along the pipe length, and calculating the hydrodynamic coefficients for drag, lift, and added mass as a function of this gap. The developed FE model may be applied to study the global static/dynamic on-bottom behavior of the pipeline, and to evaluate the effects of Seabed Intervention such as rock dumping and trenching. 3-D FE simulations are presented at the end of the paper as design examples.

Jo A Ose - One of the best experts on this subject based on the ideXlab platform.

  • a finite element model for in situ behavior of offshore pipelines on uneven Seabed and its application to on bottom stability
    The Proceedings of the ... International Offshore and Polar Engineering Conference, 1999
    Co-Authors: Jo A Ose, Pe R Nystrom, Pe Damsleth
    Abstract:

    This paper presents a Finite Element (FE) model for simulation of the in-situ behavior of offshore pipelines laid on a 3-D Seabed, with focus on on-bottom stability, The Seabed is produced in the FE model based on 3-D survey data (Digital Terrain Model, DTM) from the area where the pipeline is to be installed. In the in-place analysis part of the model, the load history of laying, flooding, pressure testing, and operation is simulated. In the on-bottom stability analysis part, wave and current loading is applied as a restart of the relevant loading condition and the dynamic behavior of the pipeline is investigated. The importance of simulating the true load history before applying the hydrodynamic loads is that it gives a more correct initial pipe configuration and force distribution prior to the stability analysis. A matter that complicates the on-bottom stability analysis of pipelines on a 3-D Seabed is the fact that the hydrodynamic coefficients among other things are dependent on the Seabed proximity. This problem has been solved in the FE model by calculating the gaps between the pipe and the Seabed at multiple, equally spaced points along the pipe length, and calculating the hydrodynamic coefficients for drag, lift, and added mass as a function of this gap. The developed FE model may be applied to study the global static/dynamic on-bottom behavior of the pipeline, and to evaluate the effects of Seabed Intervention such as rock dumping and trenching. 3-D FE simulations are presented at the end of the paper as design examples.

Pe R Nystrom - One of the best experts on this subject based on the ideXlab platform.

  • a finite element model for in situ behavior of offshore pipelines on uneven Seabed and its application to on bottom stability
    The Proceedings of the ... International Offshore and Polar Engineering Conference, 1999
    Co-Authors: Jo A Ose, Pe R Nystrom, Pe Damsleth
    Abstract:

    This paper presents a Finite Element (FE) model for simulation of the in-situ behavior of offshore pipelines laid on a 3-D Seabed, with focus on on-bottom stability, The Seabed is produced in the FE model based on 3-D survey data (Digital Terrain Model, DTM) from the area where the pipeline is to be installed. In the in-place analysis part of the model, the load history of laying, flooding, pressure testing, and operation is simulated. In the on-bottom stability analysis part, wave and current loading is applied as a restart of the relevant loading condition and the dynamic behavior of the pipeline is investigated. The importance of simulating the true load history before applying the hydrodynamic loads is that it gives a more correct initial pipe configuration and force distribution prior to the stability analysis. A matter that complicates the on-bottom stability analysis of pipelines on a 3-D Seabed is the fact that the hydrodynamic coefficients among other things are dependent on the Seabed proximity. This problem has been solved in the FE model by calculating the gaps between the pipe and the Seabed at multiple, equally spaced points along the pipe length, and calculating the hydrodynamic coefficients for drag, lift, and added mass as a function of this gap. The developed FE model may be applied to study the global static/dynamic on-bottom behavior of the pipeline, and to evaluate the effects of Seabed Intervention such as rock dumping and trenching. 3-D FE simulations are presented at the end of the paper as design examples.

Vedeld Knut - One of the best experts on this subject based on the ideXlab platform.

  • A semi-analytical model for structural response calculations of subsea pipelines in interacting free spans
    CIMNE, 2013
    Co-Authors: Sollund Havar, Vedeld Knut
    Abstract:

    Pipeline free spans may be caused by uneven Seabed, by surrounding subsea infrastructure such as pipeline crossings or by erosion processes like Seabed scouring. On the Seabed, the pipeline is subject to wave and current loading, and in free spans the surrounding flow may give rise to vortex shedding. The vortex shedding generates oscillations in the drag and lift forces acting on the pipe [1]. If the frequencies of the force oscillations are close to one of the eigenfrequencies of the free spanning pipeline, the pipeline may experience large-amplitude vibrations. Such vibrations are termed vortex-induced vibrations (VIV), and fatigue failure due to VIV in free spans is a major risk factor for offshore pipelines [2,3]. Moreover, the natural frequency of a free span decreases quickly with increasing span length, making long spans more prone to VIV-induced fatigue damage. Since the cost of Seabed Intervention in order to reduce span lengths is high, modern design codes, like Det Norske Veritas' recommended practice provisions, DNV-RP-F105 “Free Spanning Pipelines” [4], allow for the occurrence of VIV as long as the accumulated fatigue damage is accounted for

Sollund Havar - One of the best experts on this subject based on the ideXlab platform.

  • A semi-analytical model for structural response calculations of subsea pipelines in interacting free spans
    CIMNE, 2013
    Co-Authors: Sollund Havar, Vedeld Knut
    Abstract:

    Pipeline free spans may be caused by uneven Seabed, by surrounding subsea infrastructure such as pipeline crossings or by erosion processes like Seabed scouring. On the Seabed, the pipeline is subject to wave and current loading, and in free spans the surrounding flow may give rise to vortex shedding. The vortex shedding generates oscillations in the drag and lift forces acting on the pipe [1]. If the frequencies of the force oscillations are close to one of the eigenfrequencies of the free spanning pipeline, the pipeline may experience large-amplitude vibrations. Such vibrations are termed vortex-induced vibrations (VIV), and fatigue failure due to VIV in free spans is a major risk factor for offshore pipelines [2,3]. Moreover, the natural frequency of a free span decreases quickly with increasing span length, making long spans more prone to VIV-induced fatigue damage. Since the cost of Seabed Intervention in order to reduce span lengths is high, modern design codes, like Det Norske Veritas' recommended practice provisions, DNV-RP-F105 “Free Spanning Pipelines” [4], allow for the occurrence of VIV as long as the accumulated fatigue damage is accounted for