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Re: Tales of Terror #1: Architects doing engineering

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Dennis-
I thought I'd probably get a rise out of you on this :o)

I guess the bottom line is that it doesn't really matter how the "analysis" is performed as long as the resulting construction is adequate to meet the code required loads. If you model your beam on infinitely stiff supports, the middle one gets more load. If you hung it on 3 rubber bands they would each carry equal loads. For typical wood framed residential construction I think we're a lot closer to the second model than the first. Testing & the plain language of the code confirm this to my satisfaction (up to aspect ratios of 1:6 per Ed Diekmann IIRC) .

It's true that "I've been doing it this way for xx years" & "27 out of 27 engineers are ignoring the code" might be an adequate defense--as long as a rigorous analysis doesn't show that the structure fails to meet the code requirements. Most of the time I just bump up the load 20% & don't worry about it. If I think it's important enough I run Woodwork's Shearwall program. Keylat is too much work.

The reason engineers ignore the code is that the plan checkers let them. City employees enjoy sovereign immunity. Do you? If the local jurisdiction has legally adopted some exception, you are covered. If they haven't, it seems like you are obligated to enforce the UBC as written.

As practicing engineers we've all made our individual peace with flexible/rigid diaphragm issue. I confess that it amuses me to occasionally revisit the matter because I'm convinced I'm correct (even though I'm an M.E./C.E. instead of a real C.E. :o) I'd hate to see a friend get into trouble because he has recently chosen to become a windmill operator instead of merely tilting at them as a hobby.

Your friend,
Chuck Utzman, P.E.

P.S. The conference was the 98SEWC in S.F. & I may have the proceedings on a CD. The testing was at the U. of Texas IIRC. I know it wasn't Ficcadente. Those tests & my discussions with Ed Diekmann, Dan Dolan, & Kelly Cobeen about the matter was plenty enough to convince me, YMMV




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