Buckling restrained braced frame

[avecillasjavier]

Hello everyone. I have a question about BRBF system. FEMA 450 recommendations say that columns forming part of the BRBF system must be checked assuming that BRB reaches its maximum strength corresponding to a 2x story drift. My question is, in a corner column, where two orthogonal BRB are coneccted, the capacity of the column should be calculated assuming that both systems reach the 2x story drift simultaneously? Is this an ober conservative combination ? There is another combination in terms of these orthogonal effects?

 

[KootK]

That does sound overly conservative to me. ASCE 7-10 has provisions for non-orthogonal load cases. Perhaps 2x the non-orthogonal drift arising from those load cases would be more reasonable. Alternately, something to the tune of 2xSQRT(Dx^2+Dy^2) sounds more rational.

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.

 

[avecillasjavier]

Thanks for your answer KootK. I will use ASCE 7-10 load case which uses 100% of the capacity requirement from one loading direction and 30% from the other direction.