High Strength Coil Rod
High Strength Coil Rod
(OP)
I'm using High Strength Coil Rod for a column to beam connection. When anchoring the rod into the column I have an edge distance of 3 1/2" (round column, square rod pattern, 4 rods each 6" off CL and 90deg apart).
Since the rods are threaded they achieve better bond than a smooth bar. Can I eliminate the use of a nut at the end to anchor the rod? If so how do I calculate the embedment length needed to develop the rods? Or do I have to follow ACI 318-02 Appendix D? I would think that Appendix D does not apply becuase it applies to headed or hooked anchors only, and does not consider the bond becuase the test are for smooth rods only. Also, for just a coil rod I would assume that there is not an edge distance problem, but if I design it as an anchor w/nut at the end then I have to consider a side face blow out and concrete breakout.
Any help suggested.
Since the rods are threaded they achieve better bond than a smooth bar. Can I eliminate the use of a nut at the end to anchor the rod? If so how do I calculate the embedment length needed to develop the rods? Or do I have to follow ACI 318-02 Appendix D? I would think that Appendix D does not apply becuase it applies to headed or hooked anchors only, and does not consider the bond becuase the test are for smooth rods only. Also, for just a coil rod I would assume that there is not an edge distance problem, but if I design it as an anchor w/nut at the end then I have to consider a side face blow out and concrete breakout.
Any help suggested.






RE: High Strength Coil Rod
RE: High Strength Coil Rod
RE: High Strength Coil Rod
RE: High Strength Coil Rod
u = 4.75 x 10*-3/2 x f'c*1/2 divided by Diameter of bolt in ksi. Tension Load (kips)= u x pi x D x Length of bolt. I hope this gets you in the right direction. Good Luck.
RE: High Strength Coil Rod
I downloaded the article. This article does not specifically address coil rods. The threads for coil rods are deeper than for normal anchor bolts, and normal anchor bolts are typically only threaded at the top for the nut. Also, I do not have a hook.
While the article is helpful, I believe that this information is likely superceeded by ACI-318-02 Appendix D, which is based on extensive research. Also, this article does not address all of the possible failure modes. You may want to refer to Appendix D for your future designs of anchor bolts.
Thanks for trying to help though.
I'm still looking for anyone who knows of any pull out tests done on high strength coil rods, to determine the applicable development length when cast in concrete without a hook, nut or washer cast in the end. I've considered using the development length of rebar comparing it to an equivalent diameter bar, but then I would be comparing a bar with 60ksi yield to one with 105ksi yield and deeper more compact grooves than the surface of re-bar.
It appears so far though that no one has done this research yet. Maybe someone will in the future...
RE: High Strength Coil Rod
I have designed anchor bolts out of A193-B7 (up to 3 inch diam) with a nut on the bottom for drilled shafts and the length depends on the vertical rebars in the drilled pier. You have to embed the a-bolts deep enough to fully develop the vertical bars where the 45 degree cone from the a-bolt bottom nut crosses the vertical rebar according to ACI 318 embeddment formulas.
I'm a steel guy and not a concrete guy so check my method out with a concrete guru.
You might also check out the Hilti Profis software CD that will tell you the Hilti product to use for any geometry.
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I have been called "A storehouse of worthless information" many times.
RE: High Strength Coil Rod
I am not using smooth rod, but coil rod which is threaded the entire length.
Good points made!
For concrete breakout capacity you have made a point that I had overlooked. I was fixated on developing the coil rod, but I forgot that I don't have to embed the coil rod until the coil rod is developed per Appendix D design. Just embed enough to transfer the force through the cone to the longitudinal bars, since concrete breakout governs over steel failure.
Thanks...delima solved. And I'm also going to check out ACI 349 for my own information.
RE: High Strength Coil Rod
Also, if the base plate you are bolting to, sits on leveling nuts rather than on the concrete, such that the anchor bolt can go into compression, you will need to make sure that you have sufficient concrete depth below the anchor bolt so you don't blow out the bottom.
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I have been called "A storehouse of worthless information" many times.
RE: High Strength Coil Rod
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I have been called "A storehouse of worthless information" many times.