Seismic Response Modification Coefficient, R

[engr567]

Per ASCE/SEI 7-05, table 12.14-1, what is the response modification coefficient for one story steel framed building with ordinary steel moment frames (no cross braces used)? Also, how do we define concentrically and eccentrically braced fames?

 

[slickdeals]

A concentric braced frame will have the bracing member frame into the intersection of a beam and column. Energy dissipation is through the yielding/bucking of the braces.
An eccentrically braced frame will have the brace frame at a beam with an eccentricity to the column. The mechanism of energy dissipation is through the yielding and cyclic behavior of this link

 

[msquared48]

With regard to the "R" value, I think they are telling you that you cannot use that system for the Simplified Method.

Looks like you have to use the 3.5 value listed in Table 12.2-1(C4) and use the Equivlent Force Method or otherwise.

Mike McCann
MMC Engineering
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