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RE: Effects of the New Code on Wood structures - good orbad?????-Part 1

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You definitely have my vote, Lynn.

I am aware of anecdotal evidence where there has been SOME "expert" witness
testimony where a rigid diaphragm analysis was cited as something that
should have been performed but wasn't. If you pay $150 per hour, you can
find an engineer who will say just about anything. However, I'm not sure how
often this occurs (once in a blue moon?) and, more importantly, I believe
the "expert" witness must demonstrate in detail the analysis that should
have been done. Given the fact that wood structures are not flexible nor are
they rigid, an accurate model might be difficult to create. If we are having
a hard time coming up with a practical methodology, so should "expert"

It seems to me that there was very little "bru ha-ha" on this subject (even
though this provision has been in the UBC since at least 1988) up until a
seminar was presented on behalf of the Structural Engineers Association of
Southern California last February. The presenters, Doug Thompson and Bill
Nelson, presented a seminar titled "1997 Uniform Building Code (UBC) Wood
Provisions". A significant portion of this seminar was dedicated to this
rigid diaphragm analysis even though this is not one of the new features of
the 1997 UBC and in fact, the presenters offer was merely a demonstration of
their own office practice.

In my opinion, this seminar was the epicenter of the FUD (fear, uncertainty
and doubt) regarding the analysis method of wood framed structures, a market
which is financially precarious anyway.

Once again, we have seen the enemy and the enemy is us.

Are wood structures failing due to the fact that the design engineer used a
flexible diaphragm analysis instead of rigid? Before I spend these precious,
difficult to bill for man hours, I sure would like to see quantifiable
damage reports showing that this "error" is a more prevalent mode of
structural failure over than, say, lack of structural observation, material
tests and inspection reports.

Screw rigid wood diaphragms.

Bill Allen, S.E.
Laguna Niguel, CA

> -----Original Message-----
> From: Lynn [mailto:lhoward(--nospam--at)]
> Sent: Thursday, July 22, 1999 8:03 PM
> To: seaint(--nospam--at)
> Subject: Re: Effects of the New Code on Wood structures - good
> orbad?????-Part 1
> But Dennis:
> These provisions have been in the Code for years, and none of us has
> been sued
> for not doing a rigid diaphragm analysis on a small wood framed
> project.  Why do
> you think that would change?  The Code has not changed, and if the
> Engineering
> community behaves in the same fashion as they have in the past and
> continues to
> ignore these provisions, then it could still be pointed out that it is
> standard
> practice for Engineers to ignore this provision in the Code.
> Maybe instead of devoting our time to try and figure out how to design
> for what increasingly
> seems to me to be a NEARLY IMPOSSIBLE set of criteria, we
> should instead
> put
> our efforts into trying to convince engineers to do "business as
> usual".  We can
> BOYCOTT the Code :)  Yeah that's it, marches in the street,
> demonstrations at Berkeley, boy
> this brings back the 60's all over again!!!  :)
> Okay, I'm getting carried away, but I seriously think that if the
> argument is that
> "what are you crying about, this has been in the code all along", then
> we should
> respond, okay, we will ALL continue to IGNORE this section of
> the Code,
> just as we
> have been doing all along.  This strategy has served us well
> so far, and
> should continue to
> do so.
> Lynn
> Seaintonln(--nospam--at) wrote:
> >
> > In a message dated 7/22/99 2:26:19 PM Pacific Daylight Time,
> > lhoward(--nospam--at) writes:
> >
> > << This is a good questions, and I would also like a
> response to this.
> >  However, my feelings are that if there are in fact no
> changes in the
> >  Code, and we as an engineering community have been
> successfully ignoring
> >  these sections of the code for 30 years, then WHY CANT WE
> >
> > Lynn - ask the engineers among us who do Expert Witness
> work. How many
> > engineers are brought into court for providing a less than
> code acceptable
> > standard of design. I think that many of us on this list
> have been the
> > defendents (fortunately I have not) in cases where the lack
> of compliace with
> > this section of the code has bitten us in the but. I think
> Chuck Greenlaw can
> > expound on this better than I, but I am aware of a number
> of cases where the
> > engineer was crusified for not following these provisions
> back to 1991.
> >
> > Dennis
> >