R,Cd,Omega values for ordinary steel frames

[Galambos]

when using an R=3 seismic response coefficient, which does not corrrespond to the given values for ordinary steel frames (moment or braced) in IBC2003 or ASCE7-02, what values should be used for Cd and Omega? i cant imagine that the Cd value is the same as in the tables, when a user modifies the R coefficient to a lower value.

 

[samdamon]

Galambos- I might be misunderstanding your question. You are using table 1617.6 in the IBC for determining R, Omega and Cd, and you want to use R=3 in the seismic analysis to minimize seismic detailing requirements? If so, Cd and Omega for use when R=3 in a "Structural steel system not specifically detailed for seismic resistanc" are given in item #7 at the end of table 1617.6