Hi Matt, I've used all of the Hydrajaws tensile testers for loading industrial rope access and climbing anchors. They are excellent units however expensive and not without particular problems for each model as I'll elaborate below. A crucial point is that Hydrajaws make testers for proof loading construction fixings so not really for anchor extraction. Practically speaking this manifests itself in very short cylinder stroke lengths generally of only 1" (25mm) so for certified climbing anchors, the user has to reset the tester multiple times for extracting anything assuming that's the intention. A newer model () has a 2" draw so a distinct help but most are limited below that. Their clevis pins tend to fit through most glue-in anchor eyes but not any expansion bolt hanger as the pin is too thick. Even if the clevis pin fits, the clearance of the clevis block against the rock surface then prevents attachment... To get round this issue, using a connector of some sort solves the problem but can create another (assuming it's strong enough)! This time it's the load bridge standoff versus leg length vs cylinder draw. The outcome of all of this is there can be insufficient space with the load bridge at maximum stand off from the rock, to still be able to link to the anchor and contract the cylinder and apply a load to extraction at full anchor embedment. Other issues revolve around the tester load capacity so the junior model of the one pictured in your post connects easily, has good cylinder stroke but is limited to around 20kN. For proof loading that's more than sufficient but useless for extracting climbing anchors. The updated version of this model has the 2" cylinder stroke and higher rating of 50kN but that's really still too low for glue-ins. If you opt for the big daddy tester (100+kN) then you get hit by a short cylinder stroke... The best of the models I used was the model (pictured) but the clevis block shaft is not thick enough and applying up to the max load of the tester (50kN) would easily bend the rod unless the tester is perfectly aligned over the fixing, something of a challenge when doing this on an uneven rock surface. Hence why these testers are designed for a flat concrete surface... I asked Jim to build a custom puller for me in because of the above issues, not least that testers available at the time could n't exact any decent loading without needing it airlifted in... Jim can easily make one to spec'. It'll rip out most fixings apart from any of his having tried! : ) Cheers
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Jim Titt
· Joined Nov · Points: 490
Feb 4, · GermanyAs Francis says the big problems (apart from cost) are the limited stroke and capacity of the commercial testers, to rip out most bolts you need 50+kN and 5-6" stroke. The commercial testers generally only need to test the bolt not pull it and if they actually need them to come out then things get real big and expensive.
I´ve made four of these (I think) with two different models. The basis is a cheapo Chinese hole punch made for steelwork (making holes in steel shuttering) and they come in 10 and 15 ton vaiations. Like all Chinese hydraulic stuff the rating is when they don´t break, not what you can achieve, normally reckon on about 1/2 unless you weigh 100kg and jump up and down on the handle.
The pull cylinder is made for a threaded adaptor which is of no use to us so you unscrew the top cap, they aren´t very tight so an oil filter wrench or similar is ok. There´s a spring inside!
Remove the piston and drill through 20mm (it´s already bored most of the way so easy enough in a pillar drill). The top cap you drill through 30mm or similar. Looks like this from the top;-
As the piston is lower than the cap you need an extension to the piston to get a nut on the pull rod (20mm stainless threadall), a piece of heavy wall pipe does this.A clevis (or whatever on the bottom of the pull bar) and a nut and washer for the top. I make the nut easier to use by welding rod onto it, it´s only finger tight anyway.Then a suitable base strong enough and high enought to get the range you want, maybe 8" or so. Mine are a ring to hold the ram (there´s a locking screw visible on the front which locates into a dimple you drill into the ram). The legs are 35mm thick-walled tube with M20 nuts welded on the bottom for the 20mm threaded rod feet (60-100mm long) so you can adjust for uneven rock. You need the tie rod running round the bottom to stop them spreading. It doesn´t look like it but the legs are actually angled slightly outwards.Then you nee to decide how to measure the force, there´s four obvious choices. A normal S-beam strain guage, a pancake strain guage, a normal hydraulic guage or an electronic pressure guage. The first two are big, heavy, expensive and need (normally) a computer to read them out (other solutions are available). Normal hyraulic pressure guages (manometers) are cheap but hard to read with much accuracy as they are small, maybe 2kN is as good as you can get). I´ve used two different ones before now, a 200bar one and a 600bar (that´s the operating pressure) to try to get more accuracy for weaker bolts. Digital manometer are the way to go nowadays as they are much cheaper nowadays, under $100 or so. They are in reality a very small strain guage inside anyway so pretty accurate and have peak load readout, you have to make your own conversion chart from the pressure to the actual pull force but when you had the ram apart you measured the piston diameter so calculating is easy! Mine is fitted into an adaptor which goes between the quick coupler and the body of the ram using the old coupler hole BUT not all of the hole punches come with the coupler, some the hose is permanent (you can retro-fit them if desired). The adaptors themselves are really hard to find and cost a fortune though! All the later ones I´ve made I drill into the ram body and tap them 3/8"BSP or whatever suits the manometer.The rod loop is to protect the guage when you throw it down the cliff! Directly under the ram on the base there is a loop welded on which you cant see, this is more or less at the balance point so you can hang the thing up on the cliff in position while you get it all set up.I actually modify the pump as well, it´s ok if you are working on the ground where you can press against the rock or the ground but on the rope you are only squeezing the handle and the pump together, I weld up the original pivot holes on the handle and re-drill them to get more mechanical advantage.To use it you hook it all up and pump away, the stroke is 25mm so BEFORE it ends you release the pressure and take up the slack with the wing nut and pump again. If you pump until the stroke ends the manometer records this as the maximum force so you have to reset each time otherwise, I´d put a red line on the tube extending the cylinder so you know when to stop.If you use weak rubbish like a steel biner to connect to the bolt and it breaks the hydraulic shock may jam the valves in the coupler preventing you from retracting the ram, a tap on the pin in the coupler will free this off.The whole thing weighs in about 12kg, better than my big one which goes in at 35kg!Takes about day to make and the whole thing looks like this (a different one).
(Structural)
(OP)
23 May 18 20:27Working 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.
(Structural)
23 May 18 21:01If 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.
(Structural)
24 May 18 22:00Look 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.
(Structural)
24 May 18 23:40Simpson Set-XP ICC 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.
(Structural)
25 May 18 00:26Pretty 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.)
(Civil/Environmental)
25 May 18 02:52Pull 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
(Structural)
25 May 18 06:20Quote (NorthCivil)
...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.
(Structural)
31 May 18 21:36Hilti came out and tested some anchors on a job we recently did.
All I know is P/A and Mc/I
(Structural)
TRM supply professional and honest service.
31 May 18 22:44In 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, the test is clearly irrelevant.2) When the intention is to test, 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.
(Structural)
31 May 18 22:51I 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.
2
Ingenuity(Structural)
1 Jun 18 04:44 ASTM E&#;17 Standard Test Methods for Field Testing of Anchors in Concrete or Masonry addresses CONFINED and UNconfined field tension tests of anchors:addresses CONFINED and UNconfined field tension tests of anchors:
(Structural)
3 Jun 18 15:00I 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.
(Structural)
(OP)
12 Jun 18 13:15The test worked. Thanks for all the help.
(Structural)
12 Jun 18 15:07"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.
(Structural)
12 Jun 18 16:16ash060, how much did you pull? The (factored) load? Or did you pull to it's calculated (ultimate) capacity?
(Structural)
(OP)
15 Jun 18 12:12It went to the 90% of yield, which is what was specified.
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