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RE: CMU connection/ welding rebar

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Title: RE: CMU connection/ welding rebar

For this condition, I weld a coupler onto the bottom of the bearing plate.  Erico and Barsplice both make couplers that weld to the plate and allow a threaded rebar to be screwed into the coupler.  I make the bar long enough to transfer the tension to the vertical reinforcment via a lap splice.

-- Joel

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Joel Adair, PE
Halff Associates, Inc.
E-mail: jadair(--nospam--at)halff.com
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-----Original Message-----
From: Andrew D. Kester [mailto:andrew(--nospam--at)baeonline.com]
Sent: Friday, April 18, 2003 8:36 AM
To: SE Web List (E-mail)
Subject: CMU connection/ welding rebar


I am looking at a very common CMU uplift connection, a steel bearing plate that supports a wood or steel beam, at the top of a wall or column which has a high uplift. I am trying to develop some alternative details. We have been using lots of epoxy bolts, but based on recently produced tables by the manufacturer, I am finding that they can be somewhat impractical because of edge distance and spacing requirements.

Alternatively, I would like to use the vertical reinforcment already in the cells to develop a much larger tension that carries the tension down to the foundation. I have done a lot of research on the Archives, and basically welding rebar should be avoided, but if you do, use A706.

Welding A706 bars to a plate- use a fillet weld? Strength of weld is the circumference of the bar= length of weld  X standard fillet weld strength? Use E80 electrodes because of A706?

One of the archives mentioned a similar connection, and he ended up going with threaded rebar in a thru bolt connection. Is this standard rebar, like Grade 40 or 60 with threads? Do the threads develop the full tensile strength of the bars? Any problems with availability? Then I just specify a lap with my main vertical reinforcment capable of developing my load or better the full yield stress of the bar?

Last alternative- deformed anchor rods, welded to the plate or through bolted. These are normally A36/A307 type bolts? Any problems with welding? Fillet welds like mentioned above? Then can you calculate development length in concrete/grout using standard formulas for deformed bars?

Any answers to any of the above questions would be greatly appreciated. PLEASE CC me directly as I am signed up for the one list email a day.

I know Harold Sprague answered a lot of the archives on this subject, so I would like to hear from him especially.

So is the AWS D1.4 something all SEs should own?? We only have AWS D1.0, so does the former only cover welding rebar?



Andrew D. Kester, EI
Structural Engineer
Bentley Architects & Engineers
665 W. Warren Ave.
Longwood, FL 32750
1-407-331-6116
andrew(--nospam--at)baeonline.com
www.baeonline.com




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