# SEAOC Vol III amplified story drift



## McEngr (Oct 19, 2011)

Can someone please verify that the Cd factor on page 17 of the SEAOC vol iii is not 4.3 and should be 5? This should be a really quick and easy check. Thanks!


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## sab35263 (Oct 21, 2011)

McEngr said:


> Can someone please verify that the Cd factor on page 17 of the SEAOC vol iii is not 4.3 and should be 5? This should be a really quick and easy check. Thanks!


On Page 6,the manual states that Cd = 5. I'm not sure why SEAOC uses ~ 4.3 in the calculation of Design Story Drift. The way I learned it was to get the Cd value from ASCE 7-05 table 12-2.1, and under B-3 the Cd value is 5 for special concentric Braced Steel Frames.


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## tws (Oct 21, 2011)

I agree Cd = 5. It seems they are using a I = 1.15 for this calc, although it is given I = 1.0.


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## jillhill (Oct 23, 2011)

anyone know if they have a 2009 version?


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