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Re: UBC 97 Diaphargm Nailing

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James Allen wrote:
> 
> I have a few questions to take you mind off the worrying about the calendar and other horrible things.
> 
> 1. Tables 23-ll-H and 23-ll-I-1 list shear values for nailing horizontal and vertical diaphragms. The shear values for blocked horizontal diaphragms are not the same as for vertical diaphragms. Why? The NDS (the basis for these tables) does not differentiate between horizontal and vertical diaphragms.
> 2. Table 23-ll-H does not list values for 8d nails in sheathing Struct I 7/16 nnd 15/32 thick. It does list values for 8d nails in these thickness for other grades of sheathing. Why? Table 23-ll-I-1 lists shear values for 8d nails in these thickness for all grades. Why the difference between the tables?
> 3. Table 23-ll-H lists only common nails while Table 23-ll-I-1 lists common or galvanized box. Why the difference?
> 4. See Table 23-ll-I-1, footnote 5, what are tumbled nailed?

I can answer part of your question.  See if you can get you hands on APA
report #138.  You can order it from the APA web site
(http://www.apawood.org/index.html) for about $10.  This report contains
all the information from the testing where the numbers in the UBC table
came from.  The bottom line is that there is insufficient understanding
to allow accurate calculations.  The numbers in the table come from
testing, not calculations.  If you try and calc them, you will actually
get less allowable load than if you use the table.

This is also your answer to question 2, the original research didn't
test every possible configuration, therefor not every sheathing and
nailing type is available in the table.  You will have to calculate
those other types by hand.  As for questions 3 & 4, I can't help you.

Respectfully
Jake Watson, E.I.T.
Salt Lake City, UT

P.S. wait a day and I will try and post a sample calc showing how to do
it by hand.