How are you Zdravo?,

Your question is a good one. The answer however is not exactly what you might want to hear! First of all the snubber in CAESAR II was never intended for use in static loading situations. I suspect that it was put in during the glory days of Nuclear power work here in America.

As such the popular way to deal with seismic loads then, was dynamic analysis. This is the way, which this works. What do I mean works? Well first we need to discuss how a true snubber works.

A snubber is intended to allow the quasi-static thermal displacements to occur freely. However, when a dynamic load is applied they hopefully become fully locked up in a couple of milliseconds. The way in which CAESAR II “locks up the snubber” is the use of (OCC) in a load case. When the OCC is used the snubber becomes a fixed boundary condition. The problem when using this in a static case when thermal displacements are present is that the snubber will be “locked” and will restrain the pipe thermally as well as for the statically applied occasional load.

So what can be done? I suggest the following approach…
1) Place a node(s) where the snubber(s) is to be attached to the system.
2) Run the required operating cases i.e., W + T + P + (F for spring can if req'd) + D (if req'd)
3) Note the displacements linear and rotation that occur at the snubber node(s).
4) Call out snubbers attaching them to the piping node(s) and then cnode them to a fictitious node.
5) Then go to the displacements input screen and input the operational displacements for the cnode.
6) Finally set up your load cases….
CASE 1 (OPE) W+D1+T1+P1

CASE 2 (SUS) W+P1

CASE 3 (OCC) W+D1+T1+P1+U1(Case for algebraic summation)

CASE 4 (EXP) L4=L2-L1

CASE 5 (OCC) L5=L3-L1 (Results in U1 loads/ stresses alone)

CASE 6 (OCC) L6=L2+L5 (Weight + Pressure + U1 loads)

When you look at your restraint summary you will find that the snubber only experiences loading during the application of the uniform load and yet allow the system to be free thermally. I hope this helps I was going to write this up for the newsletter to include sketches etc.