Hi,

Does anyone have any particular formula for calculating the 'Stiffness' of pipe supports for use in Caesaer II's restraint definition dialogue box ('Stif')

I have flexible anchors, pipe supports with guides in the model. How can I calculate approximate stiffness for all these pipe supports?


Any help would be appreciated,

Regards,

Anky

Hi Anky

I suggest make a combined model (Piping + structure) or take help from structure to get stiffness.
If you like to use stiffness data by structure for better flexibility you have to add stiffness at all the supports or at least quite number of support close to critical equipments.

Regards

Habib

Thanks Habib.

But what information will the structural engineer require for giving me the stiffness?
What data will be required for the structural engineer to determine the stiffness?

Anky,

The 'rigid' structural supports will result in a conservative value of the piping expansion loads. If structural flexibility is taken into account, then the actual piping expansion loads can be smaller by some proportion of the structural stiffness versus the piping stiffness.

The piping sustained loads will remain unchanged with flexible supports, since gravity weight requires same supporting force regardless of stiffness of support.

A structural engineer once told me figures of 1E6 lb/in for vertical stiffness, and 1E5 lb/inch lateral stiffness or less for industrial structural steel designs. These would be significantly less than the default 1E12 stiffness in CAESARII.

Otherwise you will need to model the structural steel to get the 'exact' stiffness of the support points, as suggested by Habib.

I would suggest you use the default stiffness (no entry in the 'Stif' field) unless there is a known problem with a flexible support point.