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Re: Concrete Nails

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Fellow engineers,

        So far I have had four replies (two through SEAINT and two private).
There were some requests for more information or clarification so here it is.

        The two 2x6 are vertical, in the form of a column with the end grain
of the column (s-p-f material) bearing on the side grain of the beam (500
p.s.i. allowable compression perpendicular to the grain in the plane of the
plies according to the catalogue I have) giving a contact area of 3.5" by 3".

        The reaction is approximately 4,000 lb. working and 6,000 lb.
factored. made up of approximately equal tributary areas of family room (live
load 40 p.s.f. ) and bed room (live load 30 p.s.f.) with no reductions for
tributary area (which, by strict application of Canadian codes would not seem
to apply).

        I don't know if there were any dowels between the footing and the
wall; for my part I'm inclined to think not.  There was, however, a steel
plate 6" by 1/2" by four feet long set on top of the footing and centred under
the "post".

        I left out the steel plate information earlier because I was primarily
interested in opinions relating to nailing primary structural support wood
elements to concrete walls and on the capacity of such nails; and I didn't
want to confuse anyone with more facts.

        Thank you for your replies to date and for any others which are
forthcoming.

Regards,

H. Daryl Richardson

Scott Maxwell wrote:

> Daryl,
>
> Could you clarify something...the 2x6s...are they oriented vertically so
> that one end is sitting on the floor/footing (almost like a wood pilaster
> that is just nailed to the wall) or oriented horizontally with all the
> load being supported by the concrete nails?
>
> I would be leary about the latter.  While I don't have concrete evidence
> (no pun intended), I would think that concrete nails don't have too much
> tension capacity.  Such a situation would have been better achieve with
> either epoxied bolts, thru bolts, or expansion/sleve anchors.
>
> If the former, then I would not see to much of a problem with it.
>
> HTH,
>
> Scott
> Ypsilanti, MI
>
> On Sat, 3 May 2003, Daryl Richardson wrote:
>
> > Fellow engineers,
> >
> >         A colleague of mine, a registered P.Eng., is facing a discipline
> > committee hearing regarding the suitability of one of his structural
> > designs.  He has asked me to sit in as an expert witness on his behalf
> > and I have agreed to do so.  One of the key issues will be the
> > suitability of the use of concrete nails in securing a double 2x6 "post"
> > to a concrete foundation wall.  To help me prepare for this role I would
> > appreciate any comments you are prepared to send.
> >
> >         The situation details are the following.
> >
> >         The hearing date is May 13, but some documents must be filed by
> > May 6 (not yours, of course).
> >
> >         The project is standard residential wood frame construction.
> > The house is a single family "split level" located in south/central
> > Alberta.  Seismic is virtually zero; wind is fairly high; but neither of
> > these are applicable to the case.  Usually a structural engineer is not
> > involved with a single family residence in Alberta unless there is some
> > special circumstance such as an unusual beam arrangement, a retaining
> > wall, or some problem such as the one I am describing develops.
> >
> >         The floor system is 2x10 floor joists supported on laminated
> > wood beams (possibly MicroLam or ParaLam both of which are made op of
> > approximately 1/8" laminations with the glue plane vertical and
> > totalling 3.5" in width) which are, in turn, supported on columns.
> > Normally, there is a pocket cast in the foundation wall to support the
> > end beam beam reaction; but on this project the pocket was omitted,
> > hence the problem.
> >
> >         The foundation wall is 8" thick; the strength and age of the
> > concrete are unknown.  Normally, concrete strength would be about 2,500
> > p.s.i. and it could be normal or sulphate resistant.  One may speculate
> > that the concrete age might be from 5 to 15 days.  Below the wall is a
> > footing 6" thick and 16" wide.  There is no requirement for reinforcing
> > steel in residential concrete basements although some builders place ten
> > millimetre or #4 bars horizontally at 15" centres.
> >
> >         Since the beam pockets were omitted my colleague got involved.
> > His solution was to place a 2x6 "on the flat", against the wall and nail
> > it to the wall using ten 5" long by 3/16" diameter concrete nails.  He
> > then took a second 2x6 and nailed this directly to the first using "an
> > appropriate number of ordinary wire nails".  This provides a 3" seat for
> > the laminated beam.  The double 2x6 are approximately 5' long or less
> > and are also in contact with the wall's strip footing.  The slab on
> > grade basement floor is placed directly on top of the wall footing
> > encasing the double 2x6 post.  Unless I have been misinformed there has
> > been no indication of a failure taking place.
> >
> >         Please comment on a) the suitability of using concrete nails in
> > this way, b) the capacity of such nails, or c) anything else related to
> > this situation you want to.  All replies will be appreciated.
> >
> >         Thank you.
> >
> > Regards,
> >
> > H. Daryl Richardson
> >
> >
> >
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