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RE: Anchor Bolt Pullout

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On residential construction I have witnessed the following where bent anchor bolts are used to attach sill plates along perimeter foundation:

 

The bolts are placed with the bend parallel to or at an acute angle to the exterior face of foundation such that when the nut is tightened the bolts’ bend turns toward the exterior face. As the nut is turned and the bolts bend is turned toward the exterior face of concrete…pop….a chunk of concrete pops out.

 

So….I started looking at bolts around perimeter prior to pour during observations, making sure they are placed such that when the nut is tightened the bend turns away from the face of concrete. Getting the contractors to not tighten while concrete is still green is also beneficial. Bent bolts are so readily available and have been used for soooo long in residential construction…….

 

Mark D. Baker

Baker Engineering

 


From: erik_g(--nospam--at)cox.net [mailto:erik_g(--nospam--at)cox.net]
Sent: Tuesday, August 05, 2008 7:04 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Anchor Bolt Pullout

 

I don't see anything wrong with using J-bolts in shearwalls to anchor the sill plate to the fdn. The majority of the load on these bolts are shear load and not tension, at least that is how I understand it. 

-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
Sent: Monday, August 04, 2008 10:15 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Anchor Bolt Pullout

You are correct.  Testing has been performed that has verified that the hook is not very effective.  The tests I reviewed many years ago were performed at Univesity of Illinois.  James Fisher had a good article on this.  It is contained in DG 1 & 7 of the AISC design guides.  After observed failures in the '70's I stopped using hooked anchor bolts.

Regards,
Harold Sprague



From: ECVAl3(--nospam--at)aol.com
Date: Mon, 4 Aug 2008 19:28:25 -0400
Subject: Anchor Bolt Pullout
To: seaint(--nospam--at)seaint.org



Going through Appendix D of ACI 318-05, it appears the pullout strength of a hooked anchor bolt (D.5.3.5) is quite a bit less than that of a headed bolt (D.5.3.4) {8 times the bearing area of a bolt head or washer net area as opposed to 0.9 times the area of the hooked leg}

Am I reading this right? If so, it looks like they are trying to negate the use of hooked anchor bolts in tension.

S.Macie

SLO,CA

.




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