I had a question about what weight is used in calculating the uniform load when it is specified as a factor of g. Is it the weight of the pipe plus contents, or weight of pipe alone? And also, is it dependant on what Sustained load cases ( i.e W or WNC) are built up in the load case editor?

Uniform load in g's is used when you want to account for loads caused by seismic activity. Reference IBC 2006 section 1613.

You do not specify a weight when you have "uniform load in g's" checked. CAESAR II calculates the weight based on your pipe size and material ie if you have a pipe that weighs 100 lb and you have a 0.1 g force on the pipe in the +x direction, CAESAR II will impose a 10 lb force in +x direction. I think your input in uniform load g's will always be between 0 and 3 g's for everywhere in the US, but maybe not including california.

Sorry, my first post did not answer your question. I think CAESAR II calculates the force based on weight of pipe, contents, and insulation. Not sure about your second question. Coade please confirm.

Your g load is based on W.

Are you sure about that Dave?

I had the same question so the other day I ran some test runs.

L1 WNC+U1-U3
L2 WNC-U1-U3
L3 WNC+U2-U3
L4 WNC-U2-U3

where, U1=0.80 GX, U2=0.80 GY and U3=0.35 GZ with +Z vert. up

I got the same results with my fluid contents set to SG=1.0 as I did with SG=0.0

Has anyone that has done test runs found differing results?

Please advise.

NozzleTwister,

Does WNC not mean 'Weight No Contents'? (rhetorical)

The specific gravity of the fluid is a moot point with WNC.

*********************************

EDIT:

WHOOPPSSS!! My bad, sorry.

I now see that WNC was not the issue/cause of concern, rather does the 'U' case include the contents/weight of the fluid, which would be affected by SG.

Please ignore/disregard my previous comments.

I guess I should run a few checks on my own.

More later...

I think Dave and ElitePV is right with their comments. You should be using W ( not WNC) in your seismic load cases to be able to account the contents as well.

This is clearly stated in the Technical Reference Guide of Caesar.

Ibrahim Demir

My opinion :
Weight loads are ... pipe weight (from pipe diameter, thicknes and specific weight pipe material),fluid weight (volumes fluid times specific weight fluid), insulation weight (2 input capibilities : uniform load or with thicknes and specific weight insulation)
I think load defination W (weight ) include pipe weight , Fluid weight
and insulation weight. But insulation defined as uniform load, then its
not include at W load.
Then must sustained load case be : W+U

In dynamic case uniform load not a mass !
In dynamic case insulation weight must be define with specific weight and thicknes.
WNC not include fluid weight, however pipe weight and insulation weight ( if input not over uniform load defined).
Right ?

I ran a few cantilevers with a variety of weights - pipe, insulation, content and one uniform g load (U1= -1 in Y).
My uniform load was always based on "W" no matter how I combined this U1.
So:
W+U1 will have the same U1 component as WNC+U1.
The U (in g's) does NOT vary in combinations. It's always based on W.

Dave, Many thanks for your reply. The case I ran however does not agree with your findings. I need to analyse a transportation case. Here is the test case I ran:

Fluid weight in input: 1SG

Load cases:
1. WNC
2. U1 (where U1= -1 in Y)
3. W
Here U1 was based on W

When I deleted load case 3, and ran cases 1 and 2 only, U1 was based on WNC even though I had fluid weight as 1SG in the input.

Look forward to your reply.