Handling Torsion Due to Thermal Loads

[SgtYui]

Does anyone have any good resources on designing pipe supports as anchor points in hot run of pipe? The sketch I have attached is something I've heard works for redirecting the torsion created from the pipe's expansion and the offset of the pipe center line and center of the wide flange beam. I've been told that the channel is much stiffer from a load in the indicated direction and will help reduce torsional forces the wide flange sees during thermal expansion/contraction. Any guidance would be appreciated.

 

[canwesteng]

No issue with taking the expansion load through the channel to the support - but is the connection at the end detailed to do that or is it just clip angles?

 

[KootK]

Is it the case that your thermal load will really present itself as an imposed thermal displacement that would be unchanged by the addition of the channel? If so, then I don't feel that the channel would be effective in shielding the beam from torsion.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SgtYui]

There are clip angles connecting the wide flange web to the column flange. I figured it would need a separate connection for the channel to ensure the load path stays out of the wide flange. Would another clip angle welded to the channel accomplish this or does this need to be a moment connection?

Also because I plan on having the channel take the expansion load do I have to account for any load acting on the WF? Would you estimate that from a stiffness ratio between the two members, channel in strong axis bending the WF in weak axis bending?

 

[KootK]

Would another clip angle welded to the channel accomplish this or does this need to be a moment connection?

Another, horizontal clip angle would be the way to go.

Would you estimate that from a stiffness ratio between the two members, channel in strong axis bending the WF in weak axis bending?

That's what I'd do if it is indeed a thermal load and not an imposed thermal displacement.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SgtYui]

KootK: This is one of the anchor points along the line so the pipe is not meant to move at this location and will be limited to how much the steel is displaced by the expansion force.

 

[KootK]

But is not the expansion force just a consequence of an expansion displacement that will be more or less the same regardless of what you use to resist the load? I guess my concern is that, by adding the channel, you'll just end up with more total expansion force to deal with without really reducing the demand on the wide flange.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SgtYui]

The force I'm worried about is the result of the pipe wanting to expand but cannot due to being anchored at this location. I wasn't assuming that the channel and wide flange were expanding due to a delta t, the pipe will be insulated and sitting off of the beam. I think I misunderstood what you meant by imposed thermal displacement.

 

[KootK]

The force I'm worried about is the result of the pipe wanting to expand but cannot due to being anchored at this location.

This is the same effect that I'm worried about as well.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SlideRuleEra]

SgtYui - The "go to" book on steam line / support design is "Piping Design & Engineering" by ITT Grinnell. Its been around since the 1960's, don't know if it is still published. My copy is a Fifth Edition from 1976.

I have not designed many pipe supports, but since the point you are considering is fixed, all thermal expansion forces in the pipe line will be resisted by the C10 channel. That is, assuming the C10 has adequate end connections and the span is short enough that its deflection is not significant. The W8 is just there to hold up the C10.

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