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Polar moment of inertia of oval shapes due to an angle in the pipe
21-04-2019, 04:24 PM,
Polar moment of inertia of oval shapes due to an angle in the pipe
When you have an angle the pipe configuration, the cross-section shape is not a circle but more like oval diameter.

For example you have a leg of an HDD with a vertical angle and this cross-section is oval and has a different horizontal and vertical moment of inertia.
You should use a variable polar moment of inertia which depends on the known 7.5 degrees of PLE around the diameter.
This moment of Inertia should be used in the calculations.

Sometimes it has a positive or a negative influence in the stressses and deflections calculations.
This is more realistic.

It would be nice if PLE would implement this, because it affects the ovalisation calculations.
26-04-2019, 09:55 AM,
RE: Polar moment of inertia of oval shapes due to an angle in the pipe
I am not sure I understand in which situations an initial oval cross-section might occur ("When you have an angle the pipe configuration" and "leg of an HDD with a vertical angle" are not descriptions I immediately understand), maybe a drawing or a more complete description might help.

There are certainly possibilities to improve the model used within Ple4Win, and we will discuss this idea internally. However, at this point it is not clear whether the increased complexity and calculation time would actually significantly influence the result. Extra accuracy of the model might be lost due to the fact that all kinds of parameters are only known within a rather broad range (think about e.g. the uncertainty of soil parameters).

All this will influence our cost-benefit analysis, and this analysis will help to determine the priority of such an addition to our program.
26-04-2019, 10:07 AM, (This post was last modified: 30-04-2019, 02:06 PM by Dr. J Foerster. Edit Reason: Not necessary to quote full previous post )
RE: Polar moment of inertia of oval shapes due to an angle in the pipe
Here you have a drawing:


Or does PLE already consider the angle of the pipe.

This is also the case for the soil parameters. The vertical diameter is not the same as the horizontal diameter in an oval shape.
30-04-2019, 02:30 PM,
RE: Polar moment of inertia of oval shapes due to an angle in the pipe
With elements, Ple4Win works with a local coordinate system with the x-axis along the pipeline axis. In that case the cross-sections are round no matter what the orientation of the pipe. See also the help file on coordinate systems ( The soil parameters are also determined along that local element coordinate system.

Only SoilNB and Topload are currently using the global coordinate system, so a slight improvement might be achieved if these are also adapted to the local coordinate system of the pipe element. I assigned ticket no J-2287 to this improvement.

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