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*Seastate Files |
 
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*Seastate Files
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*Seastate Files |
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To specify the names, and corresponding percentage occurrences, of the Flexcom simulations on which the LifeTime calculations are to be based.
Refer to Fatigue Analysis (Mode 1) for further information on this feature.
Blocks of two lines, defining the file name and the percentage occurrence. This may be preceded by an optional line relating to VIV Induced Fatigue of Pipe-in-Pipe Systems.
[PIP VIV AUTOGENERATE=Auto-Generate, Number of Periods, Number of Points per Period]
FILE=File Name
PERCENT=Percentage Occurrence, [FREQUENCY=Modal frequency]
Auto-Generate can be YES (the default) or NO. Number of Periods defaults to 1. Number of Points per Period defaults to 40. File Name should include the entire path of the included file without extension. If the file name or any part of its path contains spaces then it should be enclosed in double quotation marks. Percentage Occurrence should be between 0 and 100. The entries on the first line, and the Modal frequency input, pertain specifically to VIV fatigue.
Input: |
Description |
File Name: |
The name of the Flexcom analysis for a particular loading condition. A file extension is not required. |
Percentage Occurrence: |
The corresponding percentage occurrence, relative to other loading conditions, per annum. |
Modal Frequency: |
This input pertains specifically to VIV Induced Fatigue of Pipe-in-Pipe Systems. |
Input: |
Description |
Auto-Generate: |
Select Yes if you would like Flexcom to automatically create time histories of bending moment for the inner pipe based on static mode shapes. Select No if you intend to manually create dynamic time histories yourself. |
Number of Periods: |
The number of periods for which the automatically constructed time histories are generated. By default, the time histories are one period in length. |
Number of Points per Periods: |
The number of data points contained within a single period of the automatically constructed time histories. By default, each period contains 40 equally spaced data points. |
(a)The total percentage occurrence should sum to 100%.
(b)In the case of VIV induced fatigue of inner pipes in pipe-in-pipe systems, the computational procedure requires regular/periodic time histories of bending moment for the inner pipe. These may be automatically created by Flexcom if you set Auto-Generate to YES, in which case the moment time histories are derived from the results of a static analysis of the pipe-in-pipe system deformed into a specific mode shape. By default, the constructed time histories are one period in duration and contain 40 equally spaced data points, but you can vary these parameters if you wish. Alternatively, you can manually create dynamic time histories yourself and inform Flexcom by setting Auto-Generate to NO. This approach is more accurate in the sense that riser inertia and hydrodynamic loading is taken into account. Regardless of how the time histories are created, you must specify the Modal Frequency for each seastate. Refer to VIV Induced Fatigue of Pipe-in-Pipe Systems for further details