one of our designers want to use elastomeric pads (Fabreeka) as a support pad on pipe support structure to absorb impact loading due to water hammer - similar use as a snubber.
But they have issues with this support in Caesar II dynamic analysis.
I am unsure if this can be done (Fabreeka has varying spring rate)in CII - any ideas ?
Will this reduce the DLF ?

The CAESAR II dynamics are linear, so you cannot have a varying spring rate.

thanks Richard .

but would it be worthwhile to use an "average" spring rate ?
Also how does CII consider damping in dynamics ?

our designer currently is basing his reccommendations assumming a steel to steel" bumper" type support analysis and concluding that the results are conservative i.e. from both stress and for providing restraint loads.

Loads are in the range 500 KIPs.

I have limited knowledge of dynamics and apprehend this approach will be misleading - on both counts as well as being totally wrong from resonance perspective.

In your opinion will the use of elastomeric pads with high damping properties reatly reduce the DLF - which probably is the basic intent ?

Lastly I will appreciate if you could provide your reccommnendations for a possible path forward.
Are hydraulic snubbers an option here ?

The issue is around a 36" oil line on a rack which previuosly experienced hammering loads damaging the supports.

Hi Richard/All,

Appreciated if you could respond to my queries.

regards

Applying an average spring rate is questionable:
- How would you determine this value
- Adding stiffnesses will change the natural frequencies, and therefore all of your results. Is this conservative?

Snubbers are an option, CAESAR II includes these items as stiffnesses - so there is no averaging and you don't have to justify the numbers. Many people however don't like snubbers from the "maintenance" point of view.