ACI 318-05 Appendix D Epoxy Grouted Anchors Solution

[andres314]

funny and useful from

http://www.yenengine.com

I have been through the ACI Appendix D and have seen things that I wish I had not. I have come to understand the evil that is hidden with in it's non-logical pages. I have come to see that even the IBC 2006 has not been untouched by this evil. So as an extremely reduced explanation of epoxy anchor design, I will cover why the evil is not known by all. After a designer makes their way through the (8 or more)-Pages of calculations based on the code and all the required icc evaluations, and after they are stopped in place by the 0.75% reduction that is just required, they stumble into the ductile or brittle failure check that is required in the IBC 1908.1.16. This check for ductile and brittle failure is basically a joke because 99% of the time your concrete fails before the anchor which means that you have a brittle connection which we all know does not fall into the category as safe. So the code arbitrarily divide our capacity by 2.5. My solution is a bit outside the box but is non the less a good solution. I plan to reduce my anchor capacities by taking a hacksaw to the top of the anchor below the connection. my theory is that if i can insure my concrete capacity is greater than my anchor capacity (hens the hacksaw) ,then I can conclude that I have a ductile failure and am not required the 2.5 reduction. No big deal, but I just increased the strength of connection by 60% and all it required was a hacksaw.

 

[sdz]

Unless the bolt fractures at the saw cut before the shank yields then you still get a brittle failure :b

ACI Appendix D is based on a lot of research from Europe and correlates reasonably well with experimental results. Don't reject it just because you don't like the answers it gives.

 

[sdz]

Actually, reading that again, App D is for design of headed anchors, not epoxy anchors.

 

[andres314]

First of all, ACI Appendix D covers cast in place & post installed anchors. You are right about epoxy anchors, but epoxy anchors like the Simpson Strong-Tie Set-Xp anchorage solution are ICC evaluated and references the ACI Appendix D. Even though the code was not written to govern epoxy anchorage it does.

Second of all, I didn’t actually take a hacksaw to an anchor; however, what I wanted to point out was that based on the codes you can actually increase your capacity by selecting an anchor or designing a connection that yields/elongates before the concrete ruptures.

 

[Gumpmaster]

It was a tongue in cheek post.

Sad but true about the hacksaw.

Maybe someone should develop a 5ksi anchor bolt material? Plastic anchor bolts (definately ductile)?