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RE: Plywood shearwall in Plumbing Wall

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Rand,
I don't think the parallel exists in your argument. Shearwall capacity is
based on tested results with all elements of the shearwall in tact. Once you
remove a portion of the plate, you introduce a hinge - actually two since
there is some length to the discontinuity. Now, it you want to design the
wall on either side of the discontinuity as two shearwalls, you are free to
do so, but please provide a rational analysis of how you transfer the shear
(assuming the solid panel above the discontinuity acts like the drag element
of a panel above the window or door header) across the discontinuity through
the use of blocking and strapping. This is not done and IMO the wall loses
capacity or becomes two walls with insufficient resistance to uplift and
non-conformance to code required aspect ratio's of non-proprietary walls.

Whew! If you destroy a structural element, and for the moment let's consider
the shearwall to be one element composed of multiple components that work
together to produce the resisting capacity needed to meet the calculated
demand (lateral force), then you should be able to repair it and provide
proof through a rational method of mechanics as to how the repair should be
made.

I guess I am becoming redundant (give me one for rho).

Dennis ;0_)


Dennis S. Wish, PE


California Professional Engineer

Structural Engineering Consultant

dennis.wish(--nospam--at)verizon.net

http://www.structuralist.net

 


-----Original Message-----
From: Rand Holtham, P.E. [mailto:rand(--nospam--at)sigmaengineers.com] 
Sent: Tuesday, June 29, 2004 1:59 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Plywood shearwall in Plumbing Wall

Dennis,

let me play Devil's advocate here, What failure are you concerned about? By
analogy lets say we have a steel cant. stub beam on the side of a column.
Connect the stub to the column with a welded moment connection. let's say I
cut a section of the web out at the column to stub beam connection. will
that completely violate the connection capacity? No. Is it as strong as it
could be? No. Will it support the load? maybe, depends on the load.
Therefore it is conceivable that you may be nit picking a bit.

My humble opinion,
Rand



----- Original Message ----- 
From: "Paul Feather" <pfeather(--nospam--at)SE-Solutions.net>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, June 28, 2004 8:53 PM
Subject: Re: Plywood shearwall in Plumbing Wall


Plumbing penetrations in a shear wall plate is a very real concern,
depending on the size of the pipe there may be very little plate left.
Another problem aspect is when the penetration is in the top plates on
multi-level projects.  The assumed top plate drag line is virtually severed
and requires proper detailing to perform as intended.

We avoid using plumbing walls as shear walls.  I do not think you are being
unnecessarily concerned.

Paul Feather PE, SE
pfeather(--nospam--at)SE-Solutions.net
www.SE-Solutions.net
  ----- Original Message ----- 
  From: Dennis Wish
  To: Light_framing(--nospam--at)structuralist.net ; seaint(--nospam--at)seaint.org
  Sent: Monday, June 28, 2004 6:21 PM
  Subject: Plywood shearwall in Plumbing Wall


  I’m not sure how big a problem this is, but I am running across it a lot
in plan checking light-framing. The engineer or architect of record is not
paying attention to the location of designated shear walls and is placing
walls where plumbing will penetrate the mud sill. By design, I am careful to
avoid this as I believe it destroys the continuity of the shearwall plate. I
’ve had situations where walls were accidentally placed in a plumbing wall
and I have worked out details using 2x solid blocking placed between studs
and secured with the 2x edge down against the remaining wood sill plate. I
then end-nail the blocks through the studs and consider the plate to be
repaired (once the plywood is nailed to the face of the block above the
plate cut-out.



  I am seeing this a lot and pointing it out as a correction, but since the
code does not specifically address this issue, I don’t know if I am raising
unnecessary concerns.



  What are some of your opinions on shear walls in locations where the plate
is interrupted or made discontinuous due to a utility or drain?



  Thanks in advance,

  Dennis



  Dennis S. Wish, PE
  California Professional Engineer

  Structural Engineering Consultant

  dennis.wish(--nospam--at)verizon.net

  http://www.structuralist.net





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