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Re: Rigid plywood diaphragms

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At 05:03 PM 11/18/98 -0800, you wrote:
>
>Your opinions would be appreciated.
>
>
>Sasha Itsekson, PE
>Ingraham/ DeJesee Associates
______________________________

It's hard to reply wrongly with an invitation like this. Now for my opinions:

When you go to a seminar, you expose yourself to other people's opinions.
There is a tendency to presume that if the opinions are those of an invited
presenter, those opinions are highly accurate, or relatively authoritative,
or at mimimum, better founded than your own opinions.

Abandon that presumption. Instead trust yourself to reconsider your own
opinions with cautious reference to what the presenter said. If you can't
comfortably integrate and harmonize their new views in with what you already
understand, then reject the new stuff. If what you were exposed to doesn't
agree with itself, reject it. If it is way too certain, or the expert is
into saving you from darkly inferred perils, reject it.

Imagine that instead of an engineering seminar, you went to a religious tent
revival and were beseeched with a great batch of opinions and pronouncements
that you didn't already believe in. Wouldn't you test them skeptically as
described above?

It is astonishing how much dogmatic claptrap and bombast is being dispensed
these days in code changes and in engineering seminars concerned with
seismic and wind design. Can it be because, like with religious "facts",
seismic and wind phenomena remain so speculative, and the possibility of
ruin on "judgment" day so traumatic, that there are so many who insist they
really know? And so many who demand that we see it and do it their way? 

Frank McClure has been very diligently testing some of the latest
divinations from the seismic priesthood, and finding that more than a little
is less than credible. More power to him, and to us if we join him. 

And on reflection, Ed Diekmann, for much of what you quoted, said in effect
that the code expects certain precise distinctions be made that cannot be
made except by guesswork, and he counseled self-reliance with an eye to
basic principles of mechanics as a reasonable recourse. He too came out of
the tent a non-believer.

What about when we don't have "proper data"?  Who had proper data when the
time came for the conjugal event that happens on honeymoons? Didn't we use
the best "data" we had and carry on earnestly with the best of care anyhow?
What else is good engineering about, if it isn't proceeding carefully with
due regard for the uncertainties?

Charles O. Greenlaw  SE    Sacramento CA