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RE: 5/8" Anchor Bolts

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I'm not concerned about the rolled threads.  What confuses me (and maybe
it's just because it's late) is that NDS 11.3.6 and NDS Appendix I says that
the bolt diameter used in the tabulated values is D, not D sub r.  But
everything I've read says that full diameter (cut thread) bolts are not
generally used.  So am I designing to and then specifying something that is
not readily available (full diameter anchor bolts)?  If so, do I then need
to adjust all the NDS Table 11E values (using the Yield Limit Equations) for
as supplied diameters based on less than full diameter bolts (rolled
threads)?  

Chris
Haffner Consulting Engineering
541-478-3052
 

-----Original Message-----
From: Christopher Wright [mailto:chrisw(--nospam--at)skypoint.com] 
Sent: Wednesday, February 23, 2005 7:41 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: 5/8" Anchor Bolts


On Feb 23, 2005, at 6:34 PM, Charley Hamilton wrote:

> People have differing opinions about whether or not cut
> threads are "as good as" rolled threads.
The best CW I get over here on the dark side is that rolled threads are 
preferred. The rolling operation makes for better mechanical properties 
in the direction of rolling, which is this case follows the surface of 
the thread. rolling doesn't leave tool marks transverse to the loading 
direction either. OTOH, a properly tightened bolt doesn't experience 
heavy cyclic loading so fatigue is less of a consideration. Most of the 
machine bolt ASTM specs permit both rolled and machined threads with 
some limits. A-574 for socket head screws specifies rolled threads only 
for diameters up to 5/8 and lengths up to 4 inches. Outside these 
limits threads may be rolled, cut or ground. A-574 screws are made from 
very strong material that isn't terribly tough; the rolled thread 
requirement appears to address fatigue and fracture requirements that 
are less critical for lower strength bolts.

Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com   | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 
1864)
http://www.skypoint.com/~chrisw/


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