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RE: Tensioning Anchor Bolts

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High strength bolts are tensioned to 70% of the tension strength of A325 or A490 bolts (RCSC 2004).  ASCE Petrochem has been recommended that anchor rods should be tensioned to a maximum of 33.3% of the tensile strength of the anchor rod (ASCE Petrochem 1997).  I feel that it is reasonable (and it is my practice) to tension anchor rods to 50% of the tensile strength. 

 

I also assume 20% loss, a minimum concrete age is required, a tensioning sequence is required, use a calibrated hydraulic bolt tensioner, and retension after 14 days. 

 

By the way, if vortex shedding is even close, add strakes. 


Regards, Harold Sprague
 

From: h.d.richardson(--nospam--at)telus.net
To: seaint(--nospam--at)seaint.org
Subject: Tensioning Anchor Bolts
Date: Wed, 11 Apr 2012 11:16:50 -0600

Fellow engineers,
 
        A question has come up regarding how much pretension force should be applied to anchor bolts.  The situation is a small stack, 24" in diameter requiring twelve 1" anchor bolts, each loaded to about 12,000 pounds.  I plan to use an 8" high seat for the bolts.  Deflection under wind load is the governing criteria.
 
        Does anyone have any thoughts on this subject?
 
        Thank you in advance for your thoughts.
 
Regards,
 
H. Daryl Richardson