Code Commitee's Idea for Frames in Seismic Zone 2

[ryansteel]

Hi to all,

will someone discuss
the Code Commitee's Idea
on UBC 97 section 1921.8
"Requirements for frames in seismic zone 2"

specially 1921.8.3
in which Equake is multiplied by factor of 2

-how does it work?
-is this factor based on tests?
-where's the equivalent of this in IBC 2006

thanks