Guide support modeling

I am for this solution. Please bear in mind that to make things easier you should build a model of secondary suport, e.g. vertical steel element, then both guides attach to the same endpoint of the steel element. No only stiffness of this element would be taken into account, but also you will have all the loading grouped together, including torque, that usually would be omited if you insert only one guide. Like advised during our workshops... :-)

BTW: Luke, it would be great to have capability to report grouped loading of secondary suport this way. It still isn't so simple and requires some hand calculation...

Maciej thank you for the suggestion. I have one more question regarding your solution.
I assume that point 5104 is not connected to pipe.
What about imposed displacement of support when is not corresponding to temperature?
Can we add imposed dispacement to restraint?

Hello Pawel,

Yes, you can add impose support displacement to this support. Add it to the Anchor at 5103 in Maciej image above.

Regards,

Mike Dattilio
Bentley Product Advantage Group Analyst

===================================================

Correct, This is the top of the steel member, so need to be there to reflect the secondary suport flexibility - very usefull feature 'by the way' and of course is not the node of the pipe, and of course it is the point of interface between structure and pipe.

Hi Maciej,

Between clamp and pipe is Polyurethane rubber / foam with 150 kg/m3 density.

I modeled the support like on attached sereen shot. The outer guided supports are with gap  5 mm (in top and side direction). On the first screen shot the you will see that shoe

is designed with ability of moving.

I have a similar support for refrigeration piping where the piping has a dense foam clamped around the outside (similar to what you have mentioned above) but in this case the outer clamp is fixed.

My approach is to firstly model this as a guide with 0mm gaps all round. Even though the actual clamp is "anchored" there will be a certain amount of movement along the pipe but I am not sure if there is enough restriction to classify it as an anchor and so this part is tricky to get an accurate model of this restricted movement in the pipe axis. I need to model some restriction in movement here otherwise a seismic force along the pipe axis direction causes the piping to fails.

I have tried increasing the friction factor however this does not have much effect on the movement, the issue here I think is that there is an unspecified force clamping the pipe and the foam which isn't taken into account yet where AutoPIPE is just applying the friction coefficient to the weight force from the pipe only. I am looking at applying a concentrated force (or forces) to the pipe at the support point at present to try and give the friction coefficient a bit more to work with but no luck yet.

Has anyone devised a method to model this type of support in AutoPIPE or have any ideas?

Hello Hayden, 

I would suggest using the same modeling approach as one would use to support a pipe in a pipe. Another words, Assuming the guide is connected to a rigid location, model 2 guide supports. The first being insulation; set all gaps = 0.0 and assign a stiffness equal to that of the insulation . Then model a 2nd guide support to represent the steel ring holding the insulation. set all gaps equal to maximum amount of movement that the pipe could move if all the insulation was missing. 

Again, you could connect both guides to the ground or connect to the same support location on an anchor or steel structure. 

Regards,

Mike Dattilio
Bentley Systems Design Analyst
Design Engineering Analysis group
===================================================

Hello Hayden, 

I would suggest using the same modeling approach as one would use to support a pipe in a pipe. Another words, Assuming the guide is connected to a rigid location, model 2 guide supports. The first being insulation; set all gaps = 0.0 and assign a stiffness equal to that of the insulation . Then model a 2nd guide support to represent the steel ring holding the insulation. set all gaps equal to maximum amount of movement that the pipe could move if all the insulation was missing. 

Again, you could connect both guides to the ground or connect to the same support location on an anchor or steel structure. 

Regards,

Mike Dattilio
Bentley Systems Design Analyst
Design Engineering Analysis group
===================================================