What would you consider the unbraced length of this double angle to be?
What would you consider the unbraced length of this double angle to be?
(OP)
If I have a typical braced frame where the braces are double angles, if I use a spacer plate with a through bolt at mid-span to connect the double angles, can I consider them braced at mid-span for compressive purposes? I would assume that I could because one is in tension and the other compression, so I could make an argument saying they will not both buckle. Before I assume this, I would like to know if there is any definitive information that leans one way or another on this situation.
Here is a quick picture of what I would like the connection to look like, if it helps. It's circled in red. Any input is appreciated. I know the picture is big, I just could not figure out how to reduce it.

Here is a quick picture of what I would like the connection to look like, if it helps. It's circled in red. Any input is appreciated. I know the picture is big, I just could not figure out how to reduce it.







RE: What would you consider the unbraced length of this double angle to be?
Read this thread
http://www.eng-tips.com/viewthread.cfm?qid=258454
RE: What would you consider the unbraced length of this double angle to be?
I doubt you would see enough stiffness at the point where the cross bracing meets to assume any considerable lateral restraint. You could model this in a frame analysis program and do a buckling run if you want but I suspect buckling load factors will be quiet low for any significant racking force applied to the frame. Best practice would be to assume that only the angle member in tension is effective in my opinion (without knowing any details of the actual project).
Jake
RE: What would you consider the unbraced length of this double angle to be?
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.
RE: What would you consider the unbraced length of this double angle to be?
Interesting point you make there. I would appreciate any references you might be able to point me towards. All the angle cross bracing sets in large industrial structures I have reviewed used tension-only members in their models.
RE: What would you consider the unbraced length of this double angle to be?
Just seen slickdeals post with list of references. Most appreciated.
Jake
RE: What would you consider the unbraced length of this double angle to be?
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.
RE: What would you consider the unbraced length of this double angle to be?
RE: What would you consider the unbraced length of this double angle to be?
RE: What would you consider the unbraced length of this double angle to be?
RE: What would you consider the unbraced length of this double angle to be?
I would argue that, if you have bracing about the two geometric axes, then you have effective bracing about all possible axes, including the principals. See the sketch below.
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.
RE: What would you consider the unbraced length of this double angle to be?
As long as the angles are stitched together to buckle compositely, as they normally are, I think that the principal axes are as shown in the section in my previous post. And they're directly braced.
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.