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Re: Deep Column Moment Frames

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This is a supplement to Charlie Carter's response to Kimberley Robinson:

As suggested by Charlie, the primary problem with deep column moment frames is
their tendancy to twist.  A research report is available on this phenomenom from
the University of California at San Diego and should be available very soon from
SAC as well. In the San Diego report, it is suggested that the primary parameter
of importance is not the column depth but rather the ratio h/tf**3 which is a
torsional constant.  Some deep columns have values of this ratio comparable to
W14's.  It would probably be OK to use such sections, but SAC has not
prequalified such use, because we don't have the necessary data to assure
ourselves they work.  Perhaps in the future, additional NSF testing will fill
this void.  It is also worth noting that the research report applies principally
to RBS connections.  These are themselves torsionally weaker than some other
connections and can induce twisting ni weak columns.  It is possible that other
connections would perform better with deep columns.  Again, we don't know.

With regard to panel zones.  The new SAC criteria recommend a balanced panel
zone that begins to yeild at about the same loading as the beam.  We have found
that this produces the largest inelastic deformation capacity for the assembly
as a whole.

Here's an update on the new FEMA/SAC publications.  There are four of them:

FEMA-350 Recommended Seismic Design Criteria for New SMFs
FEMA-351 Recommended Evaluation and Upgrade Criteria for Existing SMFs
FEMA-352 Recommended Postearthquake Evaluation and Repair Criteria for SMFs
FEMA-353 Recommended Specifications and Quality Assurance Guidelines for SMFs
for Seismic Applications

These are now complete and are being printed.  FEMA will distribute these to
members of SEAOC, SEAW and a few other groups, automatically.  Others will have
to request them.

Also, a series of seminars is currently being held in San Francisco, Los Angeles
and Seattle this month. Attendees will get copies of the publications and a
series of notes, as well.



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