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RE: Plan Check (was Re: Rigid Wood Diaphragm?)

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Scott,
This is true and I have made errors (only one that I know of) in the
first spreadsheet that I wrote for seismic retrofit of unreinforced
masonry. This was also an error in the interpretation of the code.
With that said, the point I was trying to make relates well to Multi-Lat
- the freeware spreadsheet on the Structuralist.Net website. Multi-Lat
required probably close to a thousand hours writing and releasing with
known limitations. However, to accomplish this I was able to draw upon
the knowledge of those I knew who were closest to the SEAOC Seismology
Committee as well as the sample problems in the ICBO Seismic Design
Manual Volume II. I was even on the review committee for the cold-form
problem in the manual and as such had documentation (drafts) that were
given to reviewers that also allowed me to question and debate changes
from previous codes. I didn't simply accept that Doug Thompson or Bill
Nelson's problems that were published in the Wood Frame (Light-frame)
section of this design manual were correct - if I couldn't trace the
numbers I was compelled to contact them and ask. Furthermore, the use of
spreadsheets like this made it easier for others to questions those
issues in the code that SEAOC has backed down from and would make it
easier for future code writers.
The point here is that when I walked away from the finished product, I
felt that I had a much more in-depth understanding of the code. Whether
or not I agree with it won't be resolved anytime soon. However, those
that use the spreadsheet probably won't have as deep an understanding of
the code or the spreadsheets working as those who are willing to open
the program up and study it - questioning those issues they don't
understand.

We need to do this with the code and I don't think many of us do. Most
assume intent of the code writer and leave it at that. If they debate
the issue with the plan reviewer then it is a question of who is more
convincing. To this day SEA has never published an Erratum on the code
that tracks back to the original ideas that led to the publication of
the code section for light-framing. We have a good idea, especially with
the help of ACI, PCA, AISC, MIA and other material groups how to design
using the materials and historically the methodology to resist lateral
loading for seismic and wind has been pretty good. Yet the same is not
true of light-framing and there is no record of the step taken to arrive
at the current code.

Look, my opinion of the code for wood structures is well known. My point
is that those who write computer programs may have errors - but most of
the errors are probably logic errors and not interpretation of the code
unless the code is "unfinished" with it is published. The example I used
was the use of RGA 1-91 for the retrofit of unreinforced masonry back in
the 80's as we were learning and SEAOSC was "tweaking" out the code
based on the originally published ABK Method done around 1980 (give or
take a few years). I'm sure Nels Roselund has more specific information
on ABK as he worked for the "K" - John Kariotis back then. 

I think this was an exception to the rule, but the results have held up
to this date that the methods are valid but detailing has changed and
probably will continue to evolve.

Dennis

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu] 
Sent: Thursday, October 16, 2003 10:41 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Plan Check (was Re: Rigid Wood Diaphragm?)

Dennis,

Ah, be careful my friend.  Those that program/make structural software a
just as prone to misinterpreting the intent and wording of the codes.
That is why they include a nice little disclaimer that (attempts to)
absolve of all liability/responsbility.  Thus, I am _ALWAYS_ careful
when
using structural software, especially design software that makes use of
code provisions.

Regards,

Scott
Ypsilanti, MI


On Thu, 16 Oct 2003, Dennis Wish wrote:

>
> Outside of writing computer software (the ultimate in an engineers
> evolution to understanding fully what the code writer intended and to
> find mistakes in the logic of the intention at the same time) the plan
> checker offers the great majority of us who are in SOHO or small
offices
> that don't have the time or the employees to provide peer review an
> opportunity to find even one mistake or misinterpretation of the code
> that we might have that can save a life.
>



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