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RE: Wood Allowable Stresses

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Thanks for your comments.  We are lucky enough to be evaluating the
condition and are not required to comply with any code.  The evaluation
program was implemented voluntarily.  That said, I still have a "sleep"
issue with telling an owner that 150% of 1900 psi is "OK".  I have a lot of
conditions where the bending stress exceeds 2500 psi due to snow drift.  The
owner simply wants to know if they need to fix it or not.  They don't care
about stress changes and the like.

The wood stresses were likely downgraded for very good reasons.  Just
because we as engineers were using a lower factor of safety (I know even
that is arguable) 20 years ago doesn't mean we should perpetuate the
mistake.  That said, there are no visible signs of distress in the elements
and they have been there for almost 30 years.  It may be that the wood knows
more about stress than I do!  We ultimately are recommending that the
parapets be removed, although the final decision is being left to the owner.

It would still be nice to know how much of the stress change is attributed
to using full size samples and how much is from using new growth wood.

Thanks again for your comments,

Jake Watson, P.E.
Salt Lake City, UT

P.S. Barry,
	I thought I should tell you this is Eric's job and not Kelly's.


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