modeling braces by consideration of buckling

[yas]

hello everybody

I, ve modeled eccentrically braced frame but I don,t know how to consider buckling.should I use two element for every braces and how can i do that?I, ve read something about "imperfection" .would you please guid me.
thanks in advance

[fmk]

have a look at the following for a discusion of the issues:

http://opensees.berkeley.edu/wiki/index ... n_elements

[yas]

hello dear all
I,ve modeled two elements for each brace for considering buckling.now I,m going to remove some elements like a column and the related brace ,before analyzing.but I don,t know should I remove both of the brace elements or only the single element of the brace that is connected to the column to work truly in analyzing?
thanks in advance

[mhscott]

First, you should try what you are asking to see what happens. I suspect you will probably need to remove both. Removing just one could lead to rigid body motion and analysis failure.

[yas]

hello everybody
I'm considering imperfection in my braces,but I don't know about the direction of these added nodes ?for example If I want to consider l/1000 for an initial imperfection,I should use positive buckling or a negative one ?
thanks in advance