column unbraced length
column unbraced length
(OP)
Suppose I have a column 30 feet with a beam coming in at 15 feet with a knee brace 5 feet down connected to beam from the column. Would my unbraced length for the column be 10 or 15 feet?
Thanks
Thanks






RE: column unbraced length
Dik
RE: column unbraced length
RE: column unbraced length
Lower unbraced length is more complicated. Does that knee brace a destabilizing or stabilizing effect on the column? In the past, my tendency would have always been to to say 10 ft. But, now that I've been working on a lot more structure stability questions, I'm not so sure anymore.
This is one of the reasons why AISC's Direct Analysis Method can be so useful. If you perform a 2nd order analysis on that column using reduced stiffness and such then you can be confident that the actual buckling will be accounted for. If I were to use the direct analysis method, then I'd use 10 ft as my unbraced length and feel pretty confident in my results.
If I did not use the Direct Analysis Method, then I would probably use 15 ft just to give me a better comfort level.
RE: column unbraced length
RE: column unbraced length