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Re: shear values using staples and nails

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Drew:

I am not sure I see what you are seeing.  To me, the footnote definitely
has you "correct" for framing members of difference specific gravities
than DougFir or Southern Pine, but has you do it in different manners for
staples than for nails.  The note has you adjust the Struct I panels
capacities for staples whether the plywood/OSB is Struct I sheathing or
not and using a flat adjustment of 0.82 for most framing species (SG of
0.42 or greater) or 0.65 for others.  The note then has you adjust the
shearvalues for the framing with nails based upon the actual sheathing
used and adjusting those values based upon the formula of (1-(0.5-SG)) but
not more than 1.  Thus, you effectively would "adjust" the nail shear
values of the appropriate sheathing by a factor of 0.81 (lowest SG in the
NDS is 0.31) to 1.0 (any SG of 0.5 or greater would result in the
equatione resulting in 1 or greater).

My guess is the difference is likely due to the failure mode.  I would
guess that the failure of the nail based shearwalls is your typical shear
wall failure of the perimeter fastners failing by deformation of
the plywood/OSB at the nail and/or deformation (bending) of the nails.  On
the other hand, my guess is that the staple based shear walls fail purely
due to the staples and are not really effected by the sheathing or framing
wood...at least as much.

Just my thoughts.

Regards,

Scott
Adrian, MI

On Tue, 28 Mar 2006, Drew Morris wrote:

> For determining the allowable shear for OSB/plywood shearwalls, IBC
> Table 2306 (varies by edition), footnote a allows you to use the values
> for Structural 1 after correcting for the actual specific gravity when
> using staples, but not for nails.  Anyone know why this is?
>
>
>
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