Round Column with Multiple Compression Braces

[BadgerPE]

I am working on a project which involves analyzing and load rating a series of existing industrial mezzanines. Due to the configuration of the "bracing", I have 3 or even 4 braces in compression simultaneously that frame into the round columns at the same elevation. I am trying to determine the capacity of the column in that location, but have not found any information in AISC, AISC DG 24 or CIDECT DGs that indicates how to check wall plastification when there are multiple loads at the same elevation on the column. Attached are a few pictures that show what I am looking at.

Can anyone point me in the right direction or provide any insight?

 

[SlideRuleEra]

BadgerPE - For starters, I do not know how to directly solve this problem. However, there are ways to "chip away" at it. Say that you have 3 braces.
For the design loading, calculate the resultant the resultant force of the 3 braces simultaneously.
Then ignore 1 brace at a time and calculate the resultant of all combinations of 2 braces simultaneously.
Finally, ignore 2 braces at a time and examine each remaining brace, by itself.

For four braces, add an extra step to the same approach.

You will might see a general pattern to the results, but one case may stand out as unusually significant. Even if you don't see anything noteworthy, you will get an improved understanding of how the column is being loaded. That insight can lead to reasonable assumptions that can be solved. Better than looking indefinitely for an ideal solution... that may not exist.

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[SAIL3]

rather than spend time trying to track down an approximate solution(if one exists), I would add a ring @ the top and bottom of the gussets and use well-documented solutions.....

 

[KootK]

Your "branches" look to be spaced well enough apart that they could be considered independently of one another with respect to local wall plastification. As an additional check I'd add up all of the horizontal components including the column shear and apply half to either side of a fictitious annulus for a buckling check using an equation from roark's etc. Not. In Kansas. Any more.

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.

 

[Nutrin14]

Please see the CIDECT Design Guide-1 2nd edition for Multiplanar effect provisions.