difference between scbf ocbf

huangyhg

difference between scbf & ocbf
hey,
i'm having a real hard time decerning the difference between special concentrically braced frames and ordinary concentrically braced frames. i understand that it has to do with one being more ductle then the other, and that one has many more requirements for design, but conceptually i don't get it. what's this 'post-buckling' of the gusset mean? how is there any reserved strength if gusset buckles? is the goal in a scbf to have the gusset buckle first?
if anyone could start me off from scratch and explain how these two things work, or perhaps refer me to a good book/publication spelling out the differences clearly, i'd reeeeaaaaallly appreciate it.  thanks!
scbf's are capable of much more post elastic response than ocbf's.  they're detailed so that you have more plastic response prior to brace fracture.  
in ocbf's you get a limited amount of plastic response prior to brace fracture.  
this makes scbf's a more reliable system in large seismic events.  
for an even more ductile response, look at brbf's.