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Re: Is SMRSF permitted in Seismic Zone 2?

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Nice arguement, but not quite.  The UBC allows either SMRSF or IMSF
construction to be used in Zone 2.  The reward for providing the
more elaborate seismic detailing is to design for reduced seismic
forces, using Rw of 12 for SMRSF versus 8 for IMSF.  Even with the
reduced strength,  the SMRSF is probably more likely to survive the
Zone 2 event than the IMSF.  However, building a SMRSF in a Zone 2
area may be difficult to do depending upon where you are, since the
constructor may not want to provide any more reinforcing steel than
what he is used to using in that area. 
M.Johnson (mwj(--nospam--at)

> I request opinion on the following issue:
> I feel that it is not the intent of the Uniform Building Code
> (UBC), 1994 Edition, that SMRSF be used for buildings located in
> the zone of moderate seismic-risk (Zone 2). Is my view correct? I
> rely, > (a) CODE WORDING. I begin with quoting the most direct
> sections of the code, in this regard:
> Section 1631.2.7 of UBC 1994 states that Concrete frame members
> required to be a part of the lateral-force resisting system "In
> Seismic Zone 2 ... , shall as a minimum, be intermediate moment
> resisti> Section 1921.2.1.3 of UBC 1994 states that "In Seismic
> Zone 2, reinforced concrete frames resisting forces induced by
> earthquake motions shall be intermediate moment resisting
> frames..."