Tabular Output - Main Output Section

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Tabular Output - Main Output Section

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The main output section of the tabular output file presents detailed results for every node in the model. This allows an in-depth analysis of displacements, stresses/strains, support reactions and separations, tensions, and bending moments for the whole model. In the case of static analyses, the results presented are snapshot data at the end the static analysis. In the case of dynamic analyses, extreme values and ranges are computed over time and presented in tabular format. Because of the level of output provided, the data is split into two tables; Stresses/Strains & Forces. Definitions of the various parameters in the first of these are now presented, with reference to the figures 'Co-ordinates, Forces and Strains (1) (analysis.tab)' & 'Co-ordinates, Forces and Strains (1) (analysis.csv)' for the Stress/Strain case. This is then repeated for the second table, with reference to the figures 'Co-ordinates, Forces and Strains (2) (analysis.tab)' & 'Co-ordinates, Forces and Strains (2) (analysis.csv)' for the Forces case.

 

Stress/Strain

Co-ordinates, Forces and Strains (1) (analysis.tab)   

Co-ordinates, Forces and Strains (1) (analysis.tab)

Co-ordinates, Forces and Strains (1) (analysis.csv)

Co-ordinates, Forces and Strains (1) (analysis.csv)

 

1.Node Number – The number of the node in the pipeline finite element mesh.

2.Location – The region of the model where the node is located. This can be terms such as Seabed, TDP (Touchdown Point), Sagbend, OB-SB (Inflection point), Overbend, Support (including support number), Zero Gap or Tensioner.

3.X Coord – The global-X coordinate of this node.

4.Y Coord – The global-Y coordinate of this node.

5.Z Coord – The global-Z coordinate of this node.

6.Horiz Angle –The angle of the projection of the pipeline on the global Y-Z plane at this node, measured positive going from the global Y-axis to the global Z-axis.

7.Vert Angle –The angle between the pipeline and its projection on the global Y-Z plane at this node, measured positive going from the horizontal projection to the global X-axis.

8.Pipe Length - The total length of pipeline, measured from the seabed connection point to this node.

9.Axial Stress/Strain – The axial stress/strain at this node.

10.Hoop Stress/Strain – The hoop stress/strain at this node.

11.Bending Stress/Strain – The bending stress/strain at this node.

12.Total Stress/Strain – The von Mises stress/strain at this node.

As it is not possible to convert moment-curvatures to stresses for the Moment-Curvature or Ramberg-Osgood material format, the predicted stresses for postprocessing output are computed as a product of the estimated bending or von Mises strains and the user specified Young's modulus. This can lead to an over estimation of stresses above the linear limit. This does not apply to linear or non-linear stress strain materials.

13.Percentage Allowable – The Total Stress/Strain expressed as a percentage of the Allowable Stress/Strain of the pipeline material.

 

Forces

Co-ordinates, Forces and Strains (2) (analysis.tab)

Co-ordinates, Forces and Strains (2) (analysis.tab)

Co-ordinates, Forces and Strains (2) (analysis.csv)

Co-ordinates, Forces and Strains (2) (analysis.csv)

 

1.Node Number – The number of the node in the pipeline finite element mesh

2.Location – The region of the model where the node is located. This can be terms such as Seabed, TDP (Touchdown Point), Sagbend, OB-SB (Inflection point), Overbend, Support (including support number), Zero Gap or Tensioner.

3.X Coord – The global-X coordinate of this node.

4.Y Coord – The global-Y coordinate of this node.

5.Z Coord – The global-Z coordinate of this node.

6.Reaction Vert – The local external reaction force in the vertical direction. This will be zero unless the node is on the seabed or in contact with a rollerbox. See the figure below for support reactions convention.

7.Reaction Horiz – The local external reaction force in the horizontal direction. This will be zero unless the node is on the seabed or in contact with a rollerbox. See the figure below for support reactions convention.

vertical_horizontal_reaction

8.Separation Vert – The distance between the contact diameter of the pipe and the bottom of the support measured in a direction that is parallel to the plane of symmetry for the support. The figure below illustrates the vertical separation between a pipe and a V-shaped support. The contact diameter is equal to the drag diameter, which in turn defaults to the outer diameter plus twice the external coatings thickness (if present). This output is only relevant for nodes in close proximity to supports, otherwise n/a is indicated. Please note that a negative vertical separation corresponds to settlement of the pipe contact diameter into the support surfaces.

9.Separation Horiz – The distance between the centre of the pipe and the bottom of the support measured in a direction that is perpendicular to the plane of symmetry for the support. The figure below illustrates the horizontal separation between a pipe and a V-shaped support. This output is only relevant for nodes in close proximity to supports, otherwise n/a is indicated. In addition, please note that generally the direction of a positive horizontal separation is parallel to the positive sense of the vessel local z axis (sway axis) while the opposite is the case for a negative separation.

vertical_horizontal_separation

10.Bending Moment Vert – The bending moment about the local element z-axis.

11.Bending Moment Horiz – The bending moment about the local element y-axis.

12.Total Moment - The resultant bending moment at the nodal location, Mt, defined by

where My and Mz are the bending moments respectively about the local element y- and z- axes.

13.Span Length - The length of a pipeline span, measured from its start point. The start and end points of a span are designated by nodes which are: supported by guide surfaces on supports, in contact with the seabed or assigned boundary conditions (i.e. nodes experiencing some type of reaction force). The span length accumulates across a series of nodes until the span end is reached after which the span length is reset to zero.

14.Span Height - The vertical distance between the pipe contact surface and the seabed surface.