Lateral frame question

[kbsooner]

Does the 2006 IBC or current AISC restrict the use of knee brace frames? I think I've seen comments on KBMRF's before, but did not know if they are disallowed now. Any direction to technical info for this would be appreciated.

 

[kbsooner]

I did find a commentary about these on page 6.1-170 under C11.1 for OMF's. Anyone out there actually design under these stipulations?

 

[kbsooner]

That would be in the 2006 AISC Seismic Design Manual...

 

[canstruct]

How much effective these are as compared to moment frames not considering the cost issue.

 

[msquared48]

In Chapter C, "Stability Analysis and Design", section 3a on page 16.1-20 there is a shaded user note you might be interested in:

"Knee-braced frames function as moment-frame systems and should be treated as indicated in Section C1.3b. Eccentrically braced frame systems function as combined systems and should be treated as indicated in Section C1.3d."

I assume your question pertained to steel structures, for, as far as I know, there is no restriction to the use of Knee braces for wood construction, be it porches, pole structures and the like.

Mike McCann
McCann Engineering