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Re: Plywood shearwall in Plumbing Wall

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I'm not certain I grasped Rand's parallel, either, but
I believe he has a point regarding the original
question about one plumbing hole in the bottom wood
plate of a shear wall that is bolted or otherwise
connected to a foundation wall or slab (that is, a
hole in a mudsill plate...not top plates or headers or
whatever).  

The situation posed in the original question is not
much different than a mudsill with an unreinforced
splice between two adjacent plates that are butted
together to make a long run.   While we'd all like
Contractors to use mudsill plates as long as possible,
and we usually require bolts within X inches of the
ends of mudsill plates, I bet it is the rare engineer
who requires straps across joints between two adjacent
plates.  If the mudsill is not designed to be a
collector (dragging load from one horizontal location
to be resisted at another more distant location), and
if the mudsill bolts or other connections to the
foundation are fairly closely spaced, I don't see a
problem with either unreinforced butt joints or the
occasional hole from a pipe.  If if if if if...

d a v e   e v a n s 


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&#146;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 &#146;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&#146;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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