I've got a simple piece of pipe at a 45 deg incline, 18 m long. It is in the positive x and y directions.

There are 4 possible ways to create supports that are perpendicular to the pipe.

i.e.
Option 1. +Y .707 .707 0
Option 2. -Y .707 -.707 0
Option 3. +X -.707 .707 0
Option 4. -X .707 -.707 0

I've ran through all four combinations with Options 2, 3 and 4 showing identical results.

Why is the Option 1 result different?

The loads for Option 1 are similar compared with 2, 3 and 4. However the moment is 55 times greater.

Options 2, 3, & 4 define the same line of action, so they should give the same results.

The cosines in "option 1" define the direction of the pipe. The other options define a direction perpendicular to the pipe. Personally, I would use option 3, because I find it easier to explain to people.

The supports for Options 1, 2, 3 and 4 all look the same in the graphics output.

Can you confirm that Option 1 is in the direction of the pipe? If so, what would be the notation for a +Y support that is perpendicular to the pipe run?

Thanks

Dear StressedMike,

I sometimes also get confused with the different ways to model restraint directions. For this particular piece I would definitely use the GUIde function at the restraint input. Sometimes it is also useful to model a somehow skewed line along global X, Y or Z direction with GUIdes and than rotate the input using the spreadsheet.

Based on my experience the graphical representation of support directions is not always reliable.

All the best,
Veit Bockemühl

www.surgeanalysis.com
www.esn-gmbh.com

The graphical representation of skewed supports may vary from one version and build of CAESAR II to another as different bugs (mostly graphical only) are being fixed.
As far as the latest version and build of CAESAR II stands (C2_4.50_041213), all the supports display correctly.
In your case, the piping is in (1,1,0) direction, and the (1) support direction is also (1,1,0), which makes it run along the pipe centerline. You may see it if you use "Wireframe w/o Hidden Lines" or "Translucent Objects" mode on the graphics.
For skewed supports, when the direction cosines are specified, it does not make any difference what particular type you choose (X, or Y, or Z); the sign will matter, though.

Thanks.

Caesar 4.4 definitely displays +Y 0.707 0.707 0 incorrectly. Nevertheless, I now understand the concept.

i.e. supports can be imagined as vectors where the arrow will point toward the destination for positive supports (+X +Y +Z). Similarly, the arrow will point toward the origin for negative supports (-X -Y -Z).

Further to this post...

I have approximately 2000 supports to re-model so that the various pipeline supports are always perpendicular.

Is there a quick way to globally set all supports perpendicular to the direction of the pipe run?

Thanks.

Not at the present time. However, this is an excellent idea for a future capability.