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RE: what's wrong?

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I stand corrected.  These categories were a recent add and we have not chased them all the way through the code yet.  Apparently this needs to be addressed in the NEHRP first and then into the IBC and ASCE 7.  I thought that this could be handled as an editorial comment, but now I am not so sure. 

Regards,
Harold Sprague


From: jcomfort(--nospam--at)ggbse.com
To: seaint(--nospam--at)seaint.org
Subject: RE: what's wrong?
Date: Tue, 15 Jan 2008 08:10:01 -0800

There are SDCs of E & F also.  They're defined in IBC1613.5.6 for buildings located where S1 is greater than or equal to 0.75 (Occ. Category I,II or III = E, IV = F).
-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
Sent: Tuesday, January 15, 2008 7:57 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: what's wrong?

This appears to be a problem with Site Class vs. Seismic Design Category.  There are Site Classes A, B, C, D, E, and F.  There are Seismic Design Categories A, B, C, or D. 
 
IBC 1802.2.7 intended to serve as a simple trigger to require more rigorous soil testing for Seismic Design Category D adding on to the previously stated requirements for Seismic Design Category C. 
 
This is something that can be handled as an editorial change.

Regards,
Harold Sprague



From: sgordin(--nospam--at)sgeconsulting.com
To: seaint(--nospam--at)seaint.org
Subject: what's wrong?
Date: Mon, 14 Jan 2008 23:10:20 -0800

List,
 
2006 IBC and 2007 CBC, Section 1802.2.7 refers literally to "Seismic Design Category D, E, and F" per "Section 1613."
The latter section  refers to SDS A, B, C, and D (of course, no E & F).  However, the Site Class can be designated as A through F.  I guess, the above section should read "Seismic Design Category D."
 
May be it is just too late, and I am not thinking straight.  If not - was this annoying error somehow corrected? I did not see this in the errata for the printings 1, 2, and 3... 
 
And why on earth would somebody come up with this extremely confusing idea of two sets of identical designations intended to be repetitively used in the same sections of the code?  I mean, confusing not only to the practicing engineer, but, apparently, to the code writers themselves?
 
 
Finally, how are your spreadsheets moving along?  My spreadsheets for the new code are about three times longer than the previous ones.  Because of such length, as well as an extreme amount of weirdly named coefficients, the analysis is hard to follow, and the physical sense of the problem is all but lost.  
 
IBC made it all but impossible to do calcs by hand.  In the long run, this is not good.
 
Oh well...
 
V. Steve Gordin, SE
Irvine CA
 


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