Epoxy Anchors
Epoxy Anchors
(OP)
Please see attached sketch. It is Saturday morning and all I could do is make sure I hatched the concrete in the sketch.
Assume, I have a pretty big beam (say 4' x' 5'). One the left I have a #3 reinforcing bar developed subject to a tension load. The load transfer happens due to transfer of bond stresses from the bar to concrete.
On the right I have an #3 rebar epoxied into concrete (same embedment as the left). The mechanism of load transfer is again through bond stress transfer from rebar to epoxy to concrete.
In reading literature, I understand that epoxy anchors are subject to concrete tension cone breakout.
Can someone tell if there is a flaw in my understanding. If not, can you please tell me what the difference is between the two. I don't see any difference in the two other than the discontinuity that exists at the interface.
Assume, I have a pretty big beam (say 4' x' 5'). One the left I have a #3 reinforcing bar developed subject to a tension load. The load transfer happens due to transfer of bond stresses from the bar to concrete.
On the right I have an #3 rebar epoxied into concrete (same embedment as the left). The mechanism of load transfer is again through bond stress transfer from rebar to epoxy to concrete.
In reading literature, I understand that epoxy anchors are subject to concrete tension cone breakout.
Can someone tell if there is a flaw in my understanding. If not, can you please tell me what the difference is between the two. I don't see any difference in the two other than the discontinuity that exists at the interface.






RE: Epoxy Anchors
RE: Epoxy Anchors
RE: Epoxy Anchors
I guess the bar on the left is also going to have the failure of the adhesive to the concrete. I am not trying to promote a company but we use ramset reo502 for post-installing reinforcement. According to their literature, the expoxy can develop a bar over a shorter length than the provisions made in the code for cast in place concrete i.e. no microcracking. But assuming the epoxy bond with the concrete is as good as if not better than in-situ concrete then they will have the same failure plains. Best speak with the engineering division of the adhesive supplier.
RE: Epoxy Anchors
Are we saying that no concrete cone breakout needs to be checked then?
RE: Epoxy Anchors
When in doubt, just take the next small step.
RE: Epoxy Anchors
ht
RE: Epoxy Anchors
I had a similar situation and ACI's Appedix D wasn't helping me out as I had to go bigger diameter than 1.25" and deeper than 25". I spoke to Hilti about it and they referred me to back calculating ACI's bond strength for the diameter and embedment of the bar and compare it to their bond strength.
They sent me this file which helped my understanding of it. Hope it helps you.
Chip
RE: Epoxy Anchors
Is it true that a rebar with less embedment length than required will actually fail in tension by pulling out a concrete cone rather than pulling itself out due to inadequate transfer of bond stress?
RE: Epoxy Anchors
RE: Epoxy Anchors
RE: Epoxy Anchors
RE: Epoxy Anchors
Dik
RE: Epoxy Anchors
My case is not sustained tension. However, I am trying to understand behavior.