Load for an Adhesive Anchor Pull Test 3

[ash060]

Working on a project that is adding post-installed rebar into an existing foundation using epoxy. When the contractor was doing the drilling, he didn't get much resistance in the drill and suspected a void was present. They used a scope to check the holes and there were not any voids and the concrete looked sound. I recommended installing the anchors and conducting a pull test, if the pull test is good no other action is necessary.

I am on the edge about what to pull to and they are asking me what load to pull to. My initial reaction is the yield strength of the bar because that is what it is designed for, wanted to get other opinions because it is alot of load. The bars are #7 using Hilti RE 500.

 

[atrizzy]

If your embedment, edge/end distances, etc, are suitable to develop yield stress, and if that's what your bar is designed to resist in that location, yield strength seems appropriate to me.

If there are many bars you may select a few to spot test, if any fail increase the number of tests, if any of those fail, require all to be tested and the failed ones made good.

 

[CURVEB]

Look up the ICC report for the RE 500 or a similar product. I believe the corresponding Simpson product has a section in their report about proof testing. It is a percentage of the steel strength or bond strength. I would recommend using this as a starting point for guidance.

 

[sandman21]

Simpson Set-XP ICC 2508 Section 4.5.2. 67% of nominal bond strength bond stress for uncracked concrete modified for edge effects and concrete properties or 80% of minimum specific anchor element yield strength.

 

[WARose]

Pretty much all the anchor testing I've seen goes until failure. If that is not acceptable here.....test for the (required) factored/ultimate load and see if it makes it.

One thing to keep in mind with any anchor test: as you approach failure....you are going to get some serious displacements. That may be a limiting criteria as well. (Depending on your situation.)

 

[NorthCivil]

Pull to whatever your design needs? That's your call.

I've done this before, I called the hilti rep, they sent an engineer out with all the testing equipment, the hilti products, and spent the whole day doing tests with the project team free of charge.

Perks that come with the price of a 5$ per bolt

 

[Ingenuity]

...I called the hilti rep, they sent an engineer out with all the testing equipment, the hilti products, and spent the whole day doing tests with the project team free of charge.

Not anymore in North america, of the USA, at least. Both Hilti and Simpson discontinued such field testing about a year ago...citing liability issues, apparently, according to local reps from both Hilti and Simpson.

 

[Bagman2524]

Hilti came out and tested some anchors on a job we recently did.

All I know is P/A and Mc/I

 

[KootK]

In my opinion, the pull tests are mostly a waste of time for this situation anyhow. The gadget doing the pulling simultaneously pushes back on the concrete. That means that:

1) When the intention is to test anchorage, the test is clearly irrelevant.

2) When the intention is to test development, the adhesive just spills into voids anyhow unless they're utterly cavernous.

I'd only expect to see pull test failure if there was something wrong with the installation from a labor/QC perspective.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

I should add that my previous response is dependent on how shallow the anchor is and what the test setup looks like in comparison. If you spread the reaction apart far in excess of 3 h_ef, you can be legitimately testing anchorage.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Ingenuity]

ASTM E3121−17 Standard Test Methods for Field Testing of Anchors in Concrete or Masonry addresses CONFINED and UNconfined field tension tests of anchors:

 

[Whoopdedo_LSU]

I would think bond failure between epoxy and concrete would fail before the yield of the bar. In any event, I would test to 2.5x expected ASD force per IBC.

 

[ash060]

The test worked. Thanks for all the help.

 

[BridgeSmith]

"I would think bond failure between epoxy and concrete would fail before the yield of the bar."

With properly mixed epoxy and properly cleaned and prepared holes, the failure will be yield of the bar or a cone pullout failure in the concrete.

 

[WARose]

ash060, how much did you pull? The (factored) load? Or did you pull to it's calculated (ultimate) capacity?

 

[ash060]

It went to the 90% of yield, which is what was specified.