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RE: Nelson Studs Shear Capacity

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Ed,

>From the commentary for section I5 of the specification in the 3rd edition
LRFD manual, the implication is that typically the "limit state" of the
headed stud in concrete would be bearing on the concrete on the stud's
projected surface.  This makes sense to me when you look at the older
table for allowable horizontal shear load on one stud that is in section
I4 of the spec in the ASD manual and when you look at the formula in the
3rd edition LRFD, which is a function of the concrete strength and modulus
of elasticity.

The commentary in the 3rd edition LRFD manual further goes on to state
that the upper bound of the this "limit state" would be "...the product of
the cross-sectional area of the stud times its ultimate tensile strength."
This implies to me that the upper bound is the stud itself "failing" not
the weld of the stud to the steel member.  This makes sense to me.  More
than likely the weld is sized such that it will always be stronger than
the stud itself, either by being a full penetration type weld or a fillet
type weld of sufficient strength to fully "develop" the strngth of the
stud.  This could be likely be verified by reviewing the referenced
document that produced the formula used (by Ollgaard, etc).  I would check
this, but I have temporarily miss placed my CD-ROM with all the old AISC
Journal articles (if I find it soon, then I will respond again).

The end result is that the implication is that the strength of the stud
"attachment" would be the strength of the stud itself.  So, if you get the
material properties of the stud (i.e. fy and fu) then you could like
determine either the ultimate load (LRFD) or an allowable load (ASD).

Now the thing that likely throws a monkey in the wrench (or something like
that <grin>) is that the whole strength fo the stud in the above is
situation is affected by the fact that it is encased in concrete.  Does it
behave similarly if there is a "gap" between the shear surface and the
shear load, thus also allowing bending in addtion to pure shear?  With out
know what planned purpuse you have for the stud in question, it would be
difficult to really determine what the failure load or limit state of the
stud would be.  It could be pure bending of the stud, it could be a
"punching shear" failure of the material the stud is attached to if it is
thin enough, it could be pure shear, etc.

HTH,

Scott
Ypsilanti, MI


On Fri, 26 Jul 2002, Ed Najjarine wrote:

> Thanks Mark, but
> 
> This is for the allowable shear of the bolt in concrete (composite action),
> I'm looking for the shear and tension capacity of the bolt welded to steel
> plate w/o concrete. I guess I need to know the weld capacity of the stud to
> a metal plate, is it determined using AISC table J2.5 ( what type of weld
> would I consider and what size is commonly used)?
> 
> Thanks,
> 
> Ed
> 
> -----Original Message-----
> From: Mark Pemberton [mailto:Mark.Pemberton(--nospam--at)lbdg.com]
> Sent: Friday, July 26, 2002 11:13 AM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: RE: Nelson Studs Shear Capacity
> 
> 
> Qu = 0.5As(f'cEc)^1/2 per ninth edition of AISC
> (page 5-157)
> There is also table for allowables: I4.1 (page 5-59)
> 
> Mark Pemberton, P.E.
> Sacramento, CA
> 
> -----Original Message-----
> From: Ed Najjarine [mailto:enajjarine(--nospam--at)permasteelisausa.com]
> Sent: Friday, July 26, 2002 10:40 AM
> To: SEAINT (E-mail)
> Subject: Nelson Studs Shear Capacity
> 
> 
> Hi all,
> 
> Can someone please clarify the approved shear capacity of different diameter
> Nelson stud bolts welded to metal (not necessary in a composite action with
> concrete). All I can find is capacities when used With concrete / Metal deck
> assembly ( ICBO No. 2614).
> 
> Thanks in advance,
> 
> Ed Najjarine, PE
> 
> 
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