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Re: Multi-story wood framed w/lots of openings

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The author said & drew exactly what he meant.  The method utilized here aims to minimize construction cost at the expense of capacity.  It is based on a fair amount of testing (AFAIK without any 2 story testing).  Dan Dolan at VT did most of the testing (cyclical).  IMHO the cost saving from eliminating the horizontal strapping at the opening(s) isn't worth the reduced performance.

Ed Diekmann authored the rational method shown in Faherty & the ICBO manual (at pg.69).  He also supervised extensive monotonic testing that verified the approach (for someone's 450 pg. PHD thesis).

You can't "improve" the detailing without altering the internal load paths & destroying the validity of the "analysis".  Either you build/analyze the same way the tests were set up or you analyze with the free body diagrams we all know and love (see Diekmann). Adding straps to resist the uplift at the edges of the opening basically creates piers & now the 4 strap loads usually get really big.

We spent a lot of time discussing this 3 or 4 years back IIRC.  You can probably find it with an archive search.  I spent a fair amount of time discussing the analyses & testing of both methods privately with both Ed & Dan.  I haven't kept up with the CUREE work but I don't  anything has changed substantially.
Chuck Utzman, P.E.

L. Pack wrote:
On 10 Mar 2005, at 10:19, Garner, Robert wrote:

  
I just looked at the AF&PA perforated shearwall document.  The top detail of
Figure 5 on page 8 relies on nails in withdrawal to resist uplift.  I don't
agree with this.  Anyone else?  It would be easy enough to strap this joint,
however, as shown in the other connection in this detail.



Bob Garner, S.E.
    
Given the way that the figure shows a line in the wall sheathing at the bottom
plate of the upper wall and the 2nd floor sheathing interface, there would
be no transfer of load in the sheathing, and I agree that the nail identified 
to resist the uplift forces is inadequate to handle that type of loading. 

I generally show on a detail or specify that the wall sheathing span over 
the wall/rim joist connection thereby using the wall sheathing for the force
transfer to the rim joist and the lower sheathing to rim joist picking up the
load from there and transferring it down the wall.  If this type of connection 
isn't easily accomplished then I use straps to ensure transfer of load from 
the shearwall above to the shearwall below.

Good catch on the figure.


Take care,
Lloyd Pack, P.E.


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