Cold formed steel column reinforcing

[bldgdesign]

Need help with reinforcing a cold formed steel brace. Brace is inadequate due to buckling and want to add cover plates or other cold formed sections to increase the moment of inertia. I can come up with the needed moment of inertia but don't know how to determine the length of the reinforcing. I know the reinforcing doesn't have to be the full length of the member. Can anyone help with deteriming this length? Also, does anyone have an literature, or direct me to literature, that explains the design procedure. "The Shape of the Strongest Column", by J.B. Keller is an article that I have been looking for.

 

[ishvaaag]

Variable section members have significant literature, at least pertaining to the determination of K-Factors. You can download old code NBE EA-95 that has something about.

http://tocasa.iespana.es/NBE_EA+95.zip

Another way is to model the column by component segments and give it a try with some program, always with care since thin wall in this case. You may find convenient to model explicitly surmised out-of-straightness imperfections.