Hi to everybody!

I've a strange problem.I'll try to explain it in the best way.

I consider a 30inches line, 10-S schedule (7.92mm), 150RF.
You find attacched an example below:



At node 10 there's an equipement connection; at node 1000 there's a vertical restraint which sustains a flare starting after node 130.

This line has -163°C as operating temperature and 10 barg as design pressure.

At node 10 there's a thermal displacement in Z: -12.5 mm

I've considered two case:
1) at node 10 only thermal displacement in Z and null displacement inZ at node 1000
2) at node 10 a +233 mm displacement in Z (I've alredy deducted thermal displacemet) and +245.56mm displacement in Z at node 1000

I think that relative displacement among other nodes should be the same in two cases considered above.
Analysing simulation I find different values:
- between node 30 and 58 there's 9.411mm displacement in the first case while 12.763mm in the second case.
- between node 80 and 128 there's 10.894mm displacement in the first case while 8.305mm in the second case.

Why displacements are different? Why the two deflections aren't the same?
I hope somebody can help me.


Regards

Is there anyone which can help me?

Nobody think of this situation is strange or not? If somebody think of it is correct,he can explain me his reasons?

What happens after node 130? The stiffness of the rest of the system would account for a change in the displacement response between 10 and 130.

If all the other vertical (Z) restraints see the same displacements as 1000, I would expect to see the same displacement pattern between 10 and 130.

Nice graphic.

After node 130 there's a cold vent which has lateral guides from the base to the top.
The cold vent, having a vertical restraint at node 130 and lateral guides along its development, doesn't affect the rest of the system beetwen node 10 and node 128.
So,considering a displacement of +233mm (in Z axis) at node 10 and a displacement of +245.56mm at node 1000, I expect the system has the same deflection in the case we consider displacement of -12.5 mm (in Z axis) at node 10 and a displacement of 0 mm at node 1000.
In the two case considered, the relative displacement is the same.
(233-245.5=-12.5mm)
So, in all nodes considered I expect to see the same displacement in both cases.
For example: with displacements of 233 and 245.5 mm, if node 79 has a displacement of -5 mm (Z axis), also in the system having displacements of -12.5 and 0 mm I expect to see at node 79 a displacement of -5mm.
Are you agree with me?

Regards

If the system is linear and if ALL vertical boundary conditions have the same RELATIVE movements, then, yes, I agree.

Apparently, your system does not meet these criteria.

May I see your model?

You find attacched below links to download my model.

to download model with displacements copy this link:
http://www.sendspace.com/file/xbd3x6


to download model without displacements copy this link:
http://www.sendspace.com/file/8ocfxe

I hope you will give me an answer.
Thanks

Regards

I believe the difference lies in the nonlinear restraints. What happens if you remove friction at the 1000/1001 support in Z?

I notic in your restraint report that the "with" job loads node 1000 in Y (Z is up) while the "eithout" job pushes in X.

Yes! It's right! the different displacements depends on nonlinear restraints.
I removed friction at the 1000/1001 support in Z and I notice in both cases displacements are the same.

Thanks a lot