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RE: Hold downs with "Perforated Shear Wall Method" and "Force Transfer Method"

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I think I understand the intent of what you are saying, but wording does
bother me.

With wind or seismic in one direction so that the shearwall is not loaded,
but there is overall uplift on that wall, there would be no possible
"double-dipping" as the wall would not be subjected to overturning (assuming
a simple diaphragm, thus no torsional effects).

With the wind or seismic in the other direction, the wall (if a shearwall)
should be exposed to both overturning and potentially net uplift (due to
wind uplift or the vertical component of a seismic force...overall, more
logical to think about it in terms of net wind uplift) AT THE SAME TIME.
Thus, the same dead load should be resisting both the uplift AND the
overturning.  In other words, your FBD of the shearwall will have the wind
overturning force, the net uplift, and the 60% of the dead load that would
work to resist both...all as loads applied to the shearwall.  I don't
consider that "double-dipping".  I agree that if, for some reason, you check
the wall seperately for uplift and for overturning, then the same dead load
should not be used in both check...but I would think you should be checking
both uplift and overturning in the same check.

Am I missing something?

Regards,

Scott
Adrian, MI

-----Original Message-----
From: Showalter, Buddy [mailto:Buddy_Showalter(--nospam--at)afandpa.org] On Behalf Of AWC
Info
Sent: Friday, May 23, 2008 9:47 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Hold downs with "Perforated Shear Wall Method" and "Force
Transfer Method"


One caveat however, the WFCM does not use dead load to offset uplift and use
the same dead load again to offset overturning (double-dipping). So in the
WFCM tables, we only show dead load offsetting uplift loads.



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