Off-diagonal bracing systems

[darkjmf1]

Hi everybody,

I would like to know if off-diagonal (aka off-center) bracing systems are allowed in Special Concentrically Braces Frames (SCBF) according to Seismic Provisions of AISC 341-10.
Indeed I haven't found any reference to such type of bracings in the code.

Any clarification or reference about how to analyze them would be appreciated.

 

[KootK]

How "off diagonal" are your braces? Eccentrically braced frames are, obviously, quite off diagonal and they have their very own AISC seismic design classification.

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.

 

[darkjmf1]

Thank you for your answer, KootK, but may be we are talking about different things...
Please find attached a sketch of what I call "off-diagonal" bracings. They are typically used when trying to avoid openings.
I guess they are not eccentrical, but rather an specific case of concentrical.
In case they are not allowed for SCBF or any other, any suggestion of how could these situations be solved?

 

[KootK]

Oh, I see. I'm not sure that what your attempting is possible in a "special" frame. I don't think that it would be sufficiently representative of the tested conditions that led to the development of the system. Moreover, unless combined with other, alternating braces in the same line, your system would be a compression only brace in one direction which, I believe, is not considered a stable yielding mechanism.

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.

 

[structSU10]

could you just put a post on adjacent to the door jamb and create a smaller SCBF? Not as strong, but at least in line with the code arrangement.