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

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Lynn and Bill,
I think we all really agree on this but each of us seems to be willing to 
tempt fate at different degrees. In my case, I feel compelled to follow the 
numbers even though I continue to speak out against the code. I have spoken 
to others who now argue with plan reviewers to accept their work without the 
rigid diaprhagm analysis - and plan reviewers who refuse to accept the work 
without it.
Surprisingly, without liability coverage I am probably the least likely to be 
sued but the most fearful of the stress involved in having to deal with the 

Bills comment about he February 1998 Wood design seminar, I believe, is not 
quite accurate. Bill Nelson and Doug Thompson were asked to develop the 
design example in anticipation of the '97 UBC Code requirments. The example 
may or may not have been the practice of their office at the time. I have had 
email conversations with both of them and expect to meet with Bill Nelson 
this weekend as he is visiting the desert.
My impression is that both Bill and Doug don't necessarily support the 
provisions but feel that we need to do the work per code in order to find out 
the validity of the code. I disagree that we should provide the research at 
our expense.
In the present, the code is the latest law of the land. I have raised the 
concern as to how to address our liability issues from the past and SEAOSC 
seems to be responding in the new Blue Book. As of July 1st, I believe that 
we are bound to the provisions of the code until we can prove otherwise.

As a side note, I expect that many offices are developing their own computer 
programs to meet the code. I would also expect that this will simplify the 
proceedure (which is no justification for the code itself) and make it easier 
and less costly to hire an expert witness who will run the numbers and 
probably find dificencies in shearwalls.

The most important comment in Bill and Lynn's posts is - are these 
differences in methodlogies enough to affect the structural integrity of the 
building. I think not.

Dennis Wish PE

In a message dated 7/22/99 8:38:02 PM Pacific Daylight Time, 
Bill(--nospam--at) writes:

<< 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. >>