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RE: 97 UBC

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I'll quote you some items from seminar notes from an ICBO seminar on 1997
UBC:

1. Displacement for delta S is based on code required base shear.

2. Drift requirements have been adjusted to be consistent with 1997 UBC
strength design format.  

3. Use Strength Design load combinations to determine delta S.

4. For reinforced concrete ... include effect of cracked sections in
calculation of delta S. 

5. Include translational and rotational deflections in calculation of delta
S.  

Hope this helps.

> -----Original Message-----
> From: Gerard Madden [mailto:GerardM(--nospam--at)crjarch.com]
> Sent: Friday, July 02, 1999 12:40 PM
> ...
> But when I read the code, it says Delta S shall be calculated 
> using the
> design seismic forces. I am confused, does this mean STRENGTH DESIGN
> SEISMIC FORCES only or either the WORKING STRESS LEVEL FORCES or
> Strength Design Forces. To get the DELTA M drift the 0.7RDelta S is
> compared with the 0.025H limit which I would think is based on the
> Strength design force. This is all destroyed if I am forced to compare
> the wall deflection capacity to a factored force diaphragm deflection.
> The wall deflection is based on the Nominal Moment and Cracked Section
> properties of the wall. The reinforcing and adequacy of the wall is
> based on the 1.1x1.4xFp. Fp being the working stress seismic
> coefficient.
> 
> If anyone has any insight on the simplified method and drift I would
> appreciate there opinion.