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RE: Lag bolt value from NDS Report 12

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Joe,

 

I think TR-12 leaves room for engineering judgment as to which moment resistance you choose to use –  or perhaps for illustration & understanding of where the 5%-offset values come from.

 

Footnote 2 of Table 1 gives the example of calculating the value of Ms and Mm if you were to use the proportional limit.  If you were to use 5%-offset dowel bending strengths, you would use the appropriate value from Table 5 or Table 6 and get different values of Ms and Mm.  Section 1.2.1 discusses the various dowel bending strengths and that the NDS is based on using the 5%-offset value.  If you want to be consistent with the NDS charts, you would use the 5%-offset value.

 

Also, by Section 1.2.2.1, use of the Adjustment Values in Table 2 to determine Nominal Design Values is based of using 5%-offset values [by elimination, since it says that the adjustments for F.pl and F.ult have not been established].

 

Nels Roselund, SE

South San Gabriel, CA

njineer(--nospam--at)att.net


From: Joe Grill [mailto:jgrill(--nospam--at)swiaz.com]
Sent: Tuesday, June 06, 2006 10:32 AM
To: 'seaint'
Subject: Lag bolt value from NDS Report 12

 

Maybe our favorite AWC guy is out there, but maybe someone else out there can answer this question.

 

I am looking at a lag bolt value and I am using Technical Report No. 12 from AWC.

 

Per footnote 2 on Table 1, Ms and Mm both use Fb,pl in the equation for yield modes IIIm, IIIs, and IV.  The example on page 10 uses Fb,5% or at least that is what is shown as used (I haven’t worked through the examples).  Is the footnote incorrect, or the example or (I suppose it could happen) am I missing something?

 

Thanks,

Joe

 

Joseph R. Grill, P.E. (Structural)

Shephard - Wesnitzer, Inc.

Civil Engineering and Surveying