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Re: Simpson wall anchors

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Charles:
Thanks for your reply.  I always thought you were not allowed to use
plywood as a tension element.  I will look into it further.

Thanks again.

Lynn  

Charles Greenlaw wrote:
> 

> 
> >>Do you just consider that the plywood and joist are tied together and
> >>essentially form a composite?
> 
>         I do, except that I don't just "consider" it on faith, but ensure
> that it works that way by adding enough additional nails from plywood to
> joist beyond the strap to take care of the shear along the faying surface
> that the strap nails generate by their action. These nails are in addition
> to what nailing for diaphragm shear requires, and enough width of sheet must
> be provided to absorb these nails and the strap length too. Treat yourself
> to a free-body diagram or two as a check.
> 
>         This concept accepts that the sheet is acting in direct tension as a
> splicing medium. You can look up plywood strength values in the APA Plywood
> Design Spec and find out if the breed of plywood you are using can handle
> this splice stress and diaphragm stresses simultaneously. I think I know
> what you will find, and it will amaze you how much stronger plywood is than
> the closest allowable nailing pattern's strength. But you have to impose
> sheet layout and dimension demands to make this scheme viable, and then be
> prepared to show why recent code prescriptives against using diaphragm
> sheathing for multiple purposes should be waived. One argument could be that
> the first 3/8 inch of the floor sheathing serves as the diaphragm, and the
> top 3/8 serves as the splice. Isn't it a pity that latter-day code revisors
> are forcing engineers into becoming Philadelphia lawyers?
> 
> >>or do you use longer nails?
> 
>         I would do this as a supplement, but not as a replacement for
> developing composite action by extra nailing beyond. Simpson's short nails
> are short versions of Common Nails; no difference in wire diameter. Extra
> length goes clear through the flange of the TJI and looks untidy. The straps
> have holes for Common Nails, with rare exception. Verify all that in the
> catalog.(I have capitalized Common Nails because of the holy regard in which
> they are held in the Los Angeles area.)
> 
> Charles O. Greenlaw  SE    Sacramento,CA