Structure and Piping together

I was wondering if modeling and analyzing both piping and structural framings would lead to much different results compared to those gained via piping analyzed solely, mainly when some 3mm gaps are considered for line stops which could be filled with structure movements/deflections. This would be worsened in seismic events.
Hence, to be short, why in most cases framings are not analyzed with piping systems?

PS my company is going to use axial gapped restraints instead of shock arrestors and I disagree;
My reason: ASME B31E does not allow using axial gapped resraints and just lateral gapped restraints can be used considering an impact factor of 2.
Company reason:"Structure will deflect in reality' and thus adds 15mm to OPE displacement as the gap.

Would you please send ur comments re this?

dears

No comments?

Depending on the pipe, the structure and all kinds of other things, there can be a significant different if the structure is modelled together with the piping.
Keep in mind that horizontal deflection can be as much as 1/250*height or more. So a structure with a height of 6 meters, can have a maximum deflection of 24mm. This will result in different piping behaviour in comparison with a fixed support.

thanks Corne.
the question is why aren't structures simultaneously added to piping models(while CAESAR II has this excellent capability) if they can have such impacts. Is it becuase of any difference in stiffness? Or are they ever compared from stiffness/rigidity point of view?

any comments for using axial gapped restraints instead of shock arrestors?

I think there is no technical answer to the question why it is not modelled together. I think there are a couple options:
- piping and structural are 2 departments and don't communicate (well).
- there is no money available for the extra modelling work required to get the structures in the piping model.
- the piping is often calculated before the structures. Piping forces are given to structural engineers, but structure flexibility is not passed back to the piping engineers.

Using an axial gapped restriant because there is some stiffness in the structure can give you an idea about the effect on the piping if the structure deflects. However the deflection depends on the piping forces and thus using a support with a set stiffness would be better modelling.

I think there must be some technical anaswer to this. I would be thankful if others could help.
Anyhow if structure is modeled in CII what is the joint type defined in the softwar? can I define them?
Another Q : is it possible to convert structural softwares like SAP to CII input file?

You can release degrees-of-freedom in the structural modeler, otherwise all six are assumed fixed (welded). No you can't convert a SAP model to a c2 model.

Dear Richard
Any comments for the following subjects?
-modeling piping and structure together for checking mutual effects
-using axial gapped restraints instead of shock arrestors

other guys;any points for the above?

Hi,
The modelling of structure will altogether change the support loading.
If you see the default rigid restraint stiffness used by CAESAR is 1.0E12 N/mm..CAESAR uses this stiffnesses for Y,X,Z and anchor supports.
If you ask a structural engineer to calculate the stifness of the pipe support , i am sure stiffness he will provide will be quite low.
In one of my projects we have used the actual support stiffness(provided by structural department)and i observed a drasctic change in support loads especailly anchor and limit stops.
Why it is not widely used is just matter of your client otherwise technically it is more realistic to take into account the supporting structure stiffness for analysis.

Yes, including a structural model will change the boundary condition behavior, and therefore the results. Assuming everything is done correctly, the system with the structure will be more accurate.

I can't comment on the issue of "gapped restraints versus shock arrestors", that is not only application dependent but likely company specific.

If so, i don´t understand why Caesar (which is the most widely used software) doesn´t have communication with other software structures. In other softwares if there is this relationship with structure software.

Following davidmunoz statement, what are the structure files which Caesar can upload to the structure builder?

At the present time c2 can only address structural models built with the c2 Structural Modeler.

What about smartplant 3D models?

c2 can import the graphic image only, as a VUE file, for visualization. At the present time c2 can only address structural models built with the c2 Structural Modeler.

Thank you very much, it is now clear to me.

What is the maximum size of the vue file that can be imported in Caesar?

One file 133 MB fail to be loaded.
Other thing I want to know is what are the settings to be done for vue file creation in order to have various types of components (e.g. structures, piping). I only have "other components"

Thank you,

Tried the second time with a 133 MB file and it works.

For the rest:
Just to understand, nobody use this feature or what?

Our VUE files have everything. There must be some setting on the S3D side. Open a Support Request on SmartSupport and ask for help.