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RE: F1554 vs A36 threaded rods

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The F1554 allows for 3 strengths of anchor rod (36, 55, & 105 ksi).  I am not aware of any problems using a threaded ASTM A36 bar.  ASTM A36 anchor rods were the standard not too many years ago. 
 
I would caution on the use of a plate washer.  The old TVA studies indicated that there was some reduction in strength using a plate washer.  The surface of a nut is more than sufficient to provide anchorage to the concrete. 
 
I would use an anchor nut and mechanically deform the threads on the anchor nut to preclude rotation.  This is done with a hammer and a center punch.  The nut is placed on the rod, and the center punch is placed on the thread adjacent to the nut.  The thread is deformed by striking the center punch with the hammer.  This is done on each side of the nut at a few places and the nut is seized by the deformations.  It only takes a few minutes.  A jam nut can be used to preclude rotation of the anchor nut, but it is only effective if you provide a large torque.
 
In lieu of mechanical deformations, you could weld the A36 rod.  It is weldable, but the nut may or may not be weldable.  It is not a big deal since the weld will just be used to prevent the nut from rotating.  I just like to avoid this, because you can easily have non weldable F1554 anchor rod materials. 

Regards, Harold Sprague


 

From: jeff_h(--nospam--at)lrpope.com
To: seaint(--nospam--at)seaint.org
Subject: F1554 vs A36 threaded rods
Date: Fri, 7 Jan 2011 11:23:41 -0700

List,

I have a PEMB steel building project where F1554 headed anchor rods were specified to anchor the building to the foundation.  However, these bolts were not ordered when they should have been and now due to time constraints the contractor wants to use A36 threaded rods with double nuts and a plate washer.  At first glance I think this looks like it would be okay, yield stress and ultimate stress ranges are the same.  However, I don’t have the ASTM publications that would tell me the difference between the two.  This is an enclosed building so exposure to the elements is minimal.  My questions are:

1.       Are there any problems of using the A36 threaded rods instead of the F1554 rods that I should be aware of? 

2.       If A36 threaded rods are a problem, as another option, is it possible to get F1554 rods threaded the entire length and are they readily available?

 

Jeff