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[SEAOC] Re: [SEAOC] Re: [SEAOC] Plywood Shearwall Deflection

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Dennis, Shafat,

I agree with Shafat that it will be hard to develop and justify a moment
connection for the plywood wall sheathing above the door opening.  Since we
can not always get the the required shear wall height to length to be 2:1 or
less, due to architectural requirements, we have looked at using braced
frames which fit in the 2x4 stud wall.  These braced frames consist of
vertical TS 3x3x3/16 tubes and TS 2x2x3/16 diagonals and horizontal members
as illustrated below..

                             _____      ___ top plate
                             |\       |
                             |    \   |
                             | \      |
                             |    \   |
                        ___|____\|___ ___ foundation
                                                   (with embed plates for

The fabrication cost + installation will run between $800 - $1000 per frame
based upon a cost estimate we got from a local steel fabricator.  The two
real problems with this solution is having to provide access holes in the
vertical and diagonal tubes for conduit an plumbing if the brace can not be
placed in a section of wall which does not have these items running through
it.  The other more serious problem is that you are depending upon the double
top plate of the wall to act as a drag line to the steel frame.  Depending on
the length of the drag line there will most likely be breaks in the double
top plate due to plumbing vents and electrical conduits which would require
special reinforcement to assure the drag line could transfer the force to the

Michael Cochran
Brian L Cochran Associates
Los Angeles, CA