Structural Factor CsCd on Pipes per EN 1991-1-4
Structural Factor CsCd on Pipes per EN 1991-1-4
(OP)
Does anyone know how to compute the structural factor (CsCd) for wind loads on pipe per EN 1991-1-4? The help document in Caesar II says it's in Annex D but I don't see anything for pipe. I see chimneys, maybe they are thinking you could use that for pipe. I'll just use CsCd = 1, if I can't find anything but I am curious to know. I'm in the US and this is my first foray into the Eurocode.





RE: Structural Factor CsCd on Pipes per EN 1991-1-4
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
Wind direction Z=1 others = 0, I would suspect means wind is directly perpendicular to pipe.
I don't have the code, or the Caesar user maual.
What does EN-1991 say about those variables?
What does Caesar say about those variables?
Reaction to change doesn't stop it
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
The code then goes on to give some cases where you can take CsCd as 1. The closest thing to pipe is a chimney with a circular cross-section whose height it less than 60 m and 6.5 times the diameter. But that's a cantilevered "pipe" so I'm not sure you can use that to justify using a value of 1.
Next the code talks about the detailed procedure for calculating CsCD, but all the cases show members with a rectangular cross-section. That leaves Annexes B, C, and D. Like I said in my OP, CAESAR help says to use Annex D but I'm not seeing how that applies to pipe.
What does CAESAR say about those variables? Not much. Here it is:
"Structural Factor [CsCd] - Structural factor used to determine the force on the vessel. This value is defined in Section of the EN 1991-1-4:2005(E) Wind load specification in Annex D. This value normally ranges between 0.90 and 1.10. The greater the structural factor value, the higher the element load."
Notice after the word "Section" there is no section number. I think they meant to put one, or they just used bad grammar. Also, why do they refer to a vessel? Isn't this for pipe also? Instead of "help" this should be called "no help".
I thought this being a worldwide forum there would be lots of people that have already figured this out. I'm guessing the reality is that people just plug in 1.0 or maybe 1.1 to be safe and move on.
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
Reaction to change doesn't stop it
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
Reaction to change doesn't stop it
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
301.5.2 Wind. The effect of wind loading shall be taken into account in the design of exposed piping. The analysis considerations and loads may be as described in ASCE 7.
ASCE 7 is model building code. Not a pipe code per se. Just to be clear, I understand you don't do the actual design of pipes using structural codes but you do use structural codes to determine the wind and seismic loads on pipe.
As far as who told me, we were asked to help out a sister company in Europe who was overloaded (we're in the US) on a job in Norway. We were given very little info, so I started hunting around and from what I could find out it seemed we should follow the Eurocodes. I opened up CAESAR II to see what codes it supported for wind and the only European code it had was EN 1991-1-4. I should stop at this point and rub it in some more. It also listed ASCE 7, IBC, NBC, and UBC, all "structural codes". Anyway, I asked my counterparts if this was the right code to use and if so could they supply the wind speed, terrain category, etc. They supplied the relevant input except for the structural factor (CsCd), thus that brings us to where we are today.
Chicopee, I got very close to the same value as CAESAR II when I plugged in CsCd=1 and used the same in a hand calculation. Not sure what that proves other than I agree with CAESAR's number. Still doesn't tell me what CsCd should be.
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
You can also use any wind load calculation method you deem is sufficient for your design.
ASCE 7 ? What do you do when it is an offshore pipeline riser below water level, or an undersea pipeline exposed to currents. Check another box in Caesar?
Reaction to change doesn't stop it
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
I'm curious, if you design pipe sans building code, how do you arrive at a wind speed?
Regarding your wise a$$ question about using Caesar, I was merely using Caesar to get an idea of what codes are popular for wind load determination. I'm not a pipe stress engineer, and I don't have one here in house at the moment to ask, so I was using any means at my disposal to find out. Caesar has a long reputation a being the preeminent pipe stress software, (not saying I agree or disagree, just what I hear) so I figured it would point me in the right direction for a viable wind code.
RE: Structural Factor CsCd on Pipes per EN 1991-1-4
Conservative maximum wind loads aren't too difficult to come by. Most refinery owners have established design values you can use out of the box.
Reaction to change doesn't stop it