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Modelling frost heave and tank settlement in Caesar

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NLHybrid

Mechanical
May 16, 2017
4
Good Day Everyone,

I am designing some piping for expansion to an outdoor potable water system (2 new insulated/heat traced FRP tanks and interconnecting 316SS piping) for a mine camp located in North-East Canada. Since this area has extreme min/max temperatures of -43C/30C, I am using Caesar to help due some challenges like limited spacing for the new tanks, frost heave (we are insulating around the new tanks but we will be using some existing sleepers, which aren't protected from frost heave, and tie into the existing tank which isn't protected from it either), and differential settling of the tanks.

In Caesar, I am trying to include a displacement of dY = -20mm (for the settling) on the same nodes as the restraints that would be a part of the tank/tank concrete and a displacement of dY = 75mm (for the frost heave) at the same nodes of restraints that will use some existing sleepers. I'm getting overspecification errors saying that I can't add these displacements at my +Y restraints (the pipe will be sitting on t-posts mounted to concrete sleepers). I understand why the error is occurring but I'm not sure how to get around it and still achieve what I am trying to do. Any advice or tips on how to do this or other things that I should be careful of?

I'm using three temperatures, 15C for T1, -43C for T2, and 30C for T3. Should I only consider the displacements up above for my sustained case and not for the expansion cases?

Any help would be appreciated, thanks.
 
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I would imagine you can use CNODES to move the restraints themselves. Common way to move supports based on thermal expansion.
 
Yes, CNODEs seem to have resolved my problem. Thanks for the tip.
 
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