Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: F1554 vs A36 threaded rods

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Tom:
 
You have brought up a good point regarding the threaded rods. However, there a few issues:
 
1. I don't thing the ACI 318 Appendix D is that accurate for deep anchors (18", 24") with a plate washer.
2. If the bond between the threaded rod and the concrete does not break, then the anchor is giving you a larger capacity than the cone. You might even be able to develop the rod in tension.
3. If the bond does break, then, you have the capacity of the cone.
 
Also, I have noticed that almost 99% of the anchors in Seismic Categories D and above, for columns along the perimeter of slab have brittle failure anyway. So, you would have to multiply the loads by 2.5. I feel a lot more confident with a deep threaded rod with plate washer.
Farzin S. Rahbar, SE
David C. Weiss Structural Engineer & Associates, Inc.
-----Original Message-----
From: Tom.Hunt(--nospam--at)fluor.com
To: seaint(--nospam--at)seaint.org
Sent: Fri, Jan 7, 2011 10:40 am
Subject: Re: F1554 vs A36 threaded rods

Jeff,

From a materials standpoint the materials are probably close enough.  The problem is the threads.  If you have performed an ACI 318 Appendix D design then the assumption is that with significant tension load the bond along the anchor bolt shaft is broken and all the force is delivered to the bottom head (nut, washer, or plate) which has enough bearing area to initiate the shear cone.  This also assumes elastic stretching over the full length of the bolt.  If the threads happen to prevent the shaft bond from breaking then you are trying to stretch over a very small length which may cause a brittle failure.

If your anchor bolts are small or most of your load is shear then I might not worry about it too much.  If you have significant tension and you have large/long bolts then you may want to consider some type of bond breaker such as multiple wrappings with Teflon tape.

Thomas Hunt, S.E.
Fluor



From:        "Jeff Hedman" <jeff_h(--nospam--at)lrpope.com>
To:        <seaint(--nospam--at)seaint.org>
Date:        01/07/2011 10:22 AM
Subject:        F1554 vs A36 threaded rods




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
 
 
------------------------------------------------------------
The information transmitted is intended only for the person
or entity to which it is addressed and may contain
proprietary, business-confidential and/or privileged material. 
If you are not the intended recipient of this message you are
hereby notified that any use, review, retransmission, dissemination,
distribution, reproduction or any action taken in reliance upon
this message is prohibited. If you received this in error, please
contact the sender and delete the material from any computer. 

Any views expressed in this message are those of the individual
sender and may not necessarily reflect the views of the company. 
------------------------------------------------------------