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RE: Changing the code (followup to Rigid Diaphragm)

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I am curious to know why ICBO has decided to bring this issue to the
forefront recently. Has there been any documentation of serious damage to
wood diaphragms or shear walls that were proven to be the result of assuming
the diaphragm as flexible? If the diaphragm is assumed to be flexible, and
in reality, because of its geometry it acts more like a rigid diaphragm,
some of the walls may get more lateral load induced in them than intended.
In my humble opinion, in a light framed wood structure the additional load
can easily get redistributed (similar to the assumption we make for concrete
beams and slabs) and eventually the other overdesigned walls will pick up
the slack. I can't imagine how this assumption would lead to serious
negative implications as it would with concrete or composite metal deck
diaphragms. I would be very interested in receiving any factual
documentation that can shed some light on this issue.

Ben Yousefi

	-----Original Message-----
	From:	Seaintonln(--nospam--at) [SMTP:Seaintonln(--nospam--at)]
	Sent:	Tuesday, May 04, 1999 1:16 PM
	To:	seaint(--nospam--at)
	Subject:	Re: Changing the code (followup to Rigid Diaphragm)

	         / '|                From the Desk             ()_________)

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	         (__)                  Dennis S. Wish PE                    

	I receive my list messages in digest format. I read all of the
	arguments related to the issue of code development and trying to
make change 
	for the better.

	Chuck Greenlaw is most closely akin to my belief's but in a much
	eloquent way (I wish I could write like that).  Barry Welliver
echoed Chuck's 
	comments and reflected many of the same feelings I have on the

	Rick Ranous has been a long time associate and I respect his
	However, he may be missing an important  and urgent liability issue:

	The provisions for rigid diaphragm analysis have been in the code as
early as 
	1988 (as pointed out by another of our list members) and has been
the same as 
	the '97 code since 1994. 

	Tom Campbell pointed out (and I tend to agree) that the attention to
	diaphragm analysis started when ICBO began doing seminars in 1998
	preparation of the '97 code changes. Little did we realize what most
of us 
	were missing from the '94 code.

	How liable are we?  If a building owner decides to sue an engineer
for damage 
	(whether a valid suit or not), how will the engineer fight the
	issue when an expert witness points out his failure to comply with
	provisions of the '94 code?

	What are we doing as a professional community to protect ourselves
	potential liability when we choose by professional judgment and with
	aceptance of the local building official to deviate to a lesser
level from 
	the code.

	Tom reminded me that the code provides the minimum standard and that

	engineers may do more than this. However, what happens when the
	standards are considered excessive?  What is the engineers
protection from 
	liability when he or she choses to do less than the code recommends?

	I don't think that we can wait for the next few code cycles to
resolve this 

	In support of Rick's comments, I contacted Tom Campbell from ICBO
	morning. He was more than willing to work with us to provide
pathways to 
	information as it develops. I suggested that he contact Bruce Bates
who is 
	the chair for the Computer Applications Committee of SEAOSC to start
the ball 
	rolling and that their efforts can work into a site on our website
or through 
	discussions on this List. Tom's offer was the first real sign of
	I've seen occur in a while and I applaud him.

	Rick, I agree with Chuck Greenlaw that we are caught in a muddle of
	and that most code committees welcome comments as long as they don't
	or adversly affect approval scheduling.  We can make change as you
	but only with cooperation from those in a possition to shepard our
	and suggestions and assure us that they are given proper

	Unfortunately, we are a society of the apathetic - silent majority
who simply 
	want to observe and not participate.  I wish they would but this may
be the 
	reason that change is so slow in occuring. 

	Any good suggestions as to the liability issue?



	Dennis S. Wish PE
	Structural Engineering Consultant