Beam Bracing Questions

[abusementpark]

If you have a interior beam framing into a perimeter beam, and the interior beam is coped to be at the same level as the perimeter beam, will this be considered a point of bracing? It seems like it wouldn't because it doesn't restrain either the top or bottom flange, like it would if it were sitting on top the perimeter beam.

Also, can anyone describe or provide a link for some general methods of providing bracing for a beam when you are concerned about lateral-torsional buckling? I hear people speak of providing bracing for beams, as if it is something easy to incorporate into the framing, I just have no visual idea of how this is accomplished.

I am sure these topics have been discussed before, I just couldn't find these specific answers when I did a search... thanks.

 

[frv]

To be honest, I can't find anything that backs up what I just posted, but I have it in my mind, so I'm fairly certain I read it somewhere (just don't know where-- wouldn't stand up in court)

 

[271828]

frv, I think "within the top one-third" could be easily mis-interpreted. Does that mean that any part of the connection can barely squeak into that 1/3 area? The other option seems to be that the entire connection, or a large part of it, lies in that area.

Unless you or someone can point to some text, I wouldn't use the 1/3 depth guideline. I'd go more subjectively, such as:

1. Girder, top flange in compression, filler beam attached near the top in the typical manner (i.e. T/STL same for both, or nearly so) = a brace point. The connection will begin a very small distance down from the top flange.

2. Girder, top flange in compression, filler beam attached more or less in the middle or below != a brace point.

Of course, as JAE and others point out, a diaphragm will often be there. I'm typing about cases in which the filler beam is providing the braced point.

We're also typing specifically about *lateral* braces. Torsional braces are a whole different deal. Web distortional stiffness is the usually the critical item that gets left outta discussions of those.