] [Thread] [Date] [Author]

["Bill Allen" <T.W.Allen(--nospam--at)cox.net>]

Roger -

And when you do (get your collective asses kicked), you will be able to
raise your fees.

At least that's our marketing plan here in CA.

:o)

Regards,

T. William (Bill) Allen, S.E. (CA #2607)
V/F (949) 248-8588
San Juan Capistrano, CA


:-----Original Message-----
:From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com] 
:Sent: Tuesday, August 26, 2003 1:49 PM
:To: seaint(--nospam--at)seaint.org
:Subject: RE: 2x2 Plate Washers for WSP Shear Wall
:
:
:No, Bill, it also occurs in Seismic Zone 2, the land of 
:infrequent large 
:earthquakes, but we will have to get our ass kicked with a moderate 
:earthquake before the public realizes it and engineers have 
:the guts enough 
:to admit that we are susceptible to large earthquakes.
:
:A. Roger Turk, P.E.(Structural)
:Tucson, Arizona
:
:Bill Allen wrote:
:
:. > Paul -
: 
:. > And this phenomena only occurs in Seismic Zones 3 & 4?
: 
:. > T. William (Bill) Allen, S.E. (CA #2607)
:. > V/F (949) 248-8588
:. > San Juan Capistrano, CA
:
:. > -----Original Message-----
:. > From: Paul Feather [mailto:pfeather(--nospam--at)SE-Solutions.net] 
:. > Sent: Tuesday, August 26, 2003 11:14 AM
:. > To: seaint(--nospam--at)seaint.org
:. > Subject: Re: 2x2 Plate Washers for WSP Shear Walls (UBC)
:
:
:. > Bill,
: 
:. > Examination of failure modes on shear wall sill plates 
:indicated that as . > the holdown and endpost deflect, there 
:is a general tension field . > developed along the wall which 
:creates tension on the sill plate in . > cross grain bending 
:relative to the anchor bolts.  The behavior is . > similar to 
:the observed failure in masonry or concrete walls as well, . > 
:principal tensile forces are on the diagonal with internal 
:resolution of . > the principal shear stresses.  This tension 
:field action was causing . > sill plates to split along the 
:bolt line thereby losing shear capacity . > at the bolts.  The 
:idealized analysis model we have always used, direct . > shear 
:with all tension and compressive forces concentrated at the 
:ends . > does not adequately account for the actual conditions.
: 
:. > A rather extensive testing program was conducted, I 
:believe at UC . > Irvine, that demonstrated the 2" plate 
:washer was an adequate measure to . > prevent premature 
:splitting of the sill plate and allow our traditional . > 
:analysis model to remain valid.  I am sure there is probably 
:more . > information available on the subject then we would 
:ever have time to . > actually read.
: 
:. > The shear wall table in chapter 23 is actually closer to 
:the "real" . > requirement as a result of tests.  Chapter 18, 
:which is horribly . > out-dated and the "conventional 
:construction" catch all for foundation . > design, was also 
:updated to require plate washers regardless of . > 
:application.  The two committees probably didn't talk to each 
:other.  It . > is one of those code things, like if a two 
:pound hammer is required . > under this condition, we will 
:make it required under all conditions so . > they can't screw it up.
: 
:. > Personally I am a bit conservative with wood shear wall 
:design.  I . > prefer to maximize the wall lengths where 
:possible and keep demand below . > the 3" E.N. threshold, 
:preferably 4".  
: 
:. > Paul Feather PE, SE
:. > pfeather(--nospam--at)SE-Solutions.net
:. > www.SE-Solutions.net
:
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