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RE: Wood structure with wood diaphragm - question on discontinuity

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-----Original Message-----
From: SDGSE(--nospam--at) [mailto:SDGSE(--nospam--at)]
Sent: Thursday, September 30, 1999 1:38 PM
To: seaint(--nospam--at)
Subject: Re: Wood structure with wood diaprhagm - question on

In a message dated 9/30/99 11:11:22 AM Pacific Daylight Time,
Seaintonln(--nospam--at) writes:

<<In the old flexible diaphragm design I would generally consider the beams
be a hinge in the diaphragm and design some or all of the columns to be
laterally restrained. However, in the new methods the roof should be
considered monolithic in nature and capable of distributing shear to the
extreme edges.
If I use the columns as I would in the past, I must penalize the structure
using an R of 2.2.>>


I have had situations similar to what you described. If you can transfer the
shear through the pony wall (which should be minimal since the roof break is
in mid span of your diaphragm) then all you have to do is develop your
at the ends of the roof break (i.e., at the side shear walls) and you are
done. I don't think you need the flag poles, but you do need to check the
stability of the posts due to the diaphragm deflection.

You can model this with a calcpad backer. Just fold it the way your roof is
and put it up right and support the ends and push the upper mid point gently
and see what happens.


Oshin Tosounian, S.E.


Could the chord be developed by using blocking and a continuous strap on the
outside of the structure at the elevation of the lower roof if the outside
of the structure is sheathed?

Joseph M. Otto, P.E.