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Re: Perforated shear wall uplift

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Joe-

On the 8x8 walls (the ones we typically tested), the shear anchors I consider "near" are the ones within 12" of the end of the wall.  The "next" shear anchor was ~40" from the end of shearwall.

This was only a concern when using hold downs with "enough" strength capacity but not enough stiffness; hold downs with excessive flexibility. Letting the sill "ride up" with the post prevented failure from cross grain bending.

For example, if a hold down allows 1/4" of post uplift at wall ultimate strength, then the sheathing is going to attempt to lift the sill a 1/4" as well.  If the "close" shear anchor is nutted down tight with a plate washer then the sill is pretty much not going to uplift at that location.  The 1/4" uplift will have to be "zeroed" over the 12" from shearwall end to the shear anchor location.  If the nut & washer are omitted on the "close" shaer anchor then the 1/4" sill uplift is zeroed out over ~40", much less trauma for the sill.

Of course with a burly HD like a SImpson PHD or a HDQ8 post uplift will be minimal and thus this whole problem is pretty much mooted.

There are a lot of HD's being spec'd that allow a fair amount of uplift so the problem does exist.

cheers
Bob



On 2/3/06, Jnapd(--nospam--at)aol.com <Jnapd(--nospam--at)aol.com> wrote:
Bob:
 
How close is near ??
 
Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA