Knee Braces and AISC 341-05

[SteelPE]

I am trying to figure out if knee braces are allowed in accordance with AISC 341-05. Now, I know if I select an R=3 system, I can basically use any system for bracing the structure I would like. However, I seem to remember reading somewhere that knee braces were allowed to be used under the criteria of an OMF. Does anyone know where in AISC 341-05 this is allowed?

 

[SteelPE]

Never fails....... I found it under the commentary for ordinary moment frames section C11.1 on page 6.1-170.

 

[jdgengineer]

Yes, knee braces are allowed under an OMF system. The only mention I am aware of is in the commentary of ASCE 341. See C11.1.

Depending on your SDC, I don't agree with your statement of being able to use any system for an R = 3.

 

[SteelPE]

Well, if you are SDC D E or F you are not allowed to use R=3.... and if you are over the height requirements for SDC A and B you are not allowed to use R=3 either.

 

[SteelPE]

That should read: If you are over the height requirements for SDC B and C your are not allowed to use R=3.