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RE: ASD vs. LRFD

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Has anyone taken a look at Section 1923 yet.  The "pull out cone" no longer
applies.  Now the calc is based on the "effective area".  This area is
defined as the projection of the cone onto the surface.  "For an anchor
which is perpendicular to the surface from which it protrudes , the
effective area is a circle."

Time to revise the "standards" I guess.

> -----Original Message-----
> From:	Paul Meyer [SMTP:PMeyer(--nospam--at)HASimons.com]
> Sent:	22 June, 1999 9:43 AM
> To:	'seaint(--nospam--at)seaint.org'
> Subject:	RE: ASD vs. LRFD
> 
> Similarly, anchors into concrete used to be designed based on the "bond
> strength" between the steel and the concrete, resulting in some very deep
> embedments of anchors.  Now we design based upon a "pull out cone" and the
> required embedments of anchors is much less.    For example, our corporate
> "standard" for 25 mm (one inch) anchors has gone from 600 mm (24 inches)
> embedment  for a hooked anchor to 250 mm (10 inches) for an anchor with a
> nut and washer on the bottom.
> 
> This doesn't mean that the old method was "wrong" in that it caused
> failures, but it was "wrong" in that it resulted in wasting material and
> was based upon an incorrect understanding of what kept the anchor in the
> concrete.  
> 
> > Isn't it somewhat irresponsible to call a design method 
> > "wrong" when the 
> > method was accepted and used for over 4 decades by all 
> > structural engineers 
> > on the continent of North America and was never questioned as to its 
> > correctness and engineering validity ??? 
> 
> See my comment about the method used to design two-way slabs 80 years ago.
> 
> 
> Was it "accepted"? Yes. 
> 
> Did it "work"? Yes. 
> 
> Was it "wrong"? Yes. 
>