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Re: Anchor Bolt Value with partial bolt length into nut

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Sid,
 
        Here is a selection of thoughts which may or may not be useful.
 
1.) Cut the bolts off and weld on a longer extension.
 
2.) Locally reduce the thickness of the base plate thereby effectively countersinking the nut.  Maybe you can machine the bottom corners of the nut thereby actually countersinking the nut.
 
3.) Reduce the grout thickness of lower the top of concrete thereby lowering the u/s base plate elevation.  This would, of course require adjustments elsewhere in the structure.
 
4.) Conduct some tests to determine the actual capacity of the bolts with reduced projection.  This may require reviewing the analysis.
 
5.) Add some dead load to reduce the tension.  This may be part of Item 4.) above.
 
6.) Drill and tap a smaller hole (say 0.75" diameter) in the top of the bolts then install a stud with a washer to assist.  This may add say 10% to the capacity determined in Item 4.) above.
 
7.) Run a 3/8" fillet weld around the inside of the nut.  I wouldn't do this personally without getting some knowledgeable advice of the effect of the welds on the nut and the bolt; but it is an option.
 
        These are, admittedly, grasping at straws; but maybe one of them will give you or someone else an other idea that will work.
 
Regards,
 
H. Daryl Richardson
----- Original Message -----
Sent: Thursday, March 03, 2011 10:15 PM
Subject: Anchor Bolt Value with partial bolt length into nut

Dear All,

 

Shorter than required length anchor bolts AB) were embedded into the concrete. The high strength bolt A449, 1.75 inch diameter is approximately ¼ inch short to fully engage the nut.

 

Is there any guideline to determine reduced capacity of the AB for tension and shear?

 

Any suggestion to improve the Anchor Bolt capacity to full value for tension and shear.

 

 

Thanks in advance.

 

Sid Lakhani