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Re: Rigid Diaphragm Analysis for Plywood Shear Walls

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    Even if you input t and E as 1, the program still takes the h and L values
you input and calculates an I.  Deflections are then calculated (proportional to
h3) for a solid wall (concrete is the only material that comes to mind).  The
relative deflections (or stiffnesses if you'd rather think of it that way) won't
be even remotely accurate for wood sheathed walls if you input their actual
heights and lengths.
    You have to do as the previous post suggested. Use the regular 4 term
expression for wood walls to determine the actual relative stiffness(or length x
capacity subject to the limitations we've discussed previously), figure out how
the Enercalc program calculates deflection, then input phony values for h and L
so that you get the correct relative stiffnesses.  Then (and only then) you can
use the program to do the torsional calculations.
    I decided it was too much work and will continue to use my simplified
spreadsheets until we see what Keylat really looks like.  Enercalc is missing out
on an important market here.  If they would do the conversion work(or show us how
to fudge the h and L inputs) I might be inclined to buy their program.  Keylat's
intimate connection with Simpson also makes me a little uncomfortable (If you
look at the technical notes you'll see they broke da into 2 pieces, one for their
steel tie downs and another for the other wood related tie down deflection
components--as if that would make bolted tie downs work or look better).
    Rumor has it that Ron Hamburger is going to publish a paper pointing out the
strength problems with eccentric tie downs and ICBO ES is finally going to
require that real deflection and strength information be published with ER
certifications.  LA was going to require the manufacturers to provide this
information, but it looks like they chickened out.  I guess if we wait long
enough we'll eventually get the information the manufacturers have been hiding.
Chuck Utzman