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(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.
Replies continue below
(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)
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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Ryan Jenks
· Joined Jul · Points: 0
Sep 18, · Lodi, CAAndrew Rational wrote: I&#;d like to see Simpson Titen bolts tested in a variety of rock types, and lengths. They are essentially lag bolts for concrete. I use them exclusively in my day job, and bolt down whole houses with them. They are easy to install (drill hole, blow out, run bolt in with an impact driver, done), and they are also easily removable if necessary. I could even donate some, or some cash to acquire them, if necessary. I&#;d be interested in sandstone, granite, and limestone, in a very dry climate, but with huge temperature extremes (-40F to 110F).
They are amazing when we have tested them in concrete so far. And impressive in shear when reusing the same holes a bunch. We are definitely going to test them in all sorts of rock.
Shane Brown
· Joined Jan · Points: 0
Sep 18, · Unknown HometownRyan Jenks wrote:Haha. This video isn't published yet but in a playlists because I have at least 6 in the bank at all times.
3/8" power bolt + 2.25" long with fixe hanger snapped bolt in shear at 28.46, 25.22 and 27.44kn. They weren't too bad actually. Ironically i haven't looked at specs yet, what are they?
I mean the Power Bolt + (a sleeve bolt) not the power stud (a wedge bolt).
The PB+ is the evolution of the ubiquitous 5 piece but it devolved.
These are the PowerBolt + (cant believe fixe still sells these!!!):The central bolt of the 3/8 is only 1/4, and specs at like 15kn or something. It will be super sensitive to over torque. This bolt was one that Greg Barnes also mentioned above. The original 3/8 PB was so ubiquitous in the US that developers (and Fixe) continue to trust the PB+ despite its terrible specs.
The PB+ above is only in plated steel. They did not devolve the Stainless version.
These are the PowerBolt + (cant believe fixe still sells these!!!):
Andrew Rational
· Joined Aug · Points: 10
Sep 18, · Unknown HometownRyan Jenks wrote:They are amazing when we have tested them in concrete so far. And impressive in shear when reusing the same holes a bunch. We are definitely going to test them in all sorts of rock.
Awesome. I look forward to the results. I cant think of anything easier, and the easy removeability is a bonus. Also, they can be placed closer to edges than expansion bolts.
Billcoe
· Joined Mar · Points: 930
Sep 18, · Pacific Northwet
Ryan and Bobby, thanks for doing this and also for sharing the data!!! I'd like to send you some stuff to examine and test if you wish. I have some larger stainless Ubolts that I was orgionally going to use as glue ins in a new area until the DAV (German rock folks) suggested never using Ubolts (although they were looking at smaller ones, like 25mm across the legs I believe- although perhaps Jim Titt can correct or confirm that. They are all over Europe).
I have 3 sizes of Ubolts, all larger than the Euro ones, the largest are beefy 1/2" x 6". I'll send you some to test and pay freight if you forward me your address. Really curious as these Ubolts are easy to get and not too costly.
Jim Titt
· Joined Nov · Points: 490
Want more information on Bolt Pull Test? Feel free to contact us.
Sep 18, · GermanyThe only U-bolts I've seen in Europe are one in an artificial crag in Berlin and the ones in the UK, predominantly in Dorset. They are all being replaced. Apart from Titan Climbing no-one has ever put one on the market as far as I know.
Why drill two holes to get a worse performing bolt apart from the problem of them opening the karabiner?
Ed Henicle
· Joined Aug · Points: 2,369
Sep 18, · Santa Rosa, CA@ Sandy - what spec is terrible on PB+ (3/8 PS 5pc)? I'm reading 17.7kN shear for the 3 inch version. Better than anything on my trad rack
Andrew Poet
· Joined Oct · Points: 161
Sep 18, · Central AZEd Henicle wrote: @ Sandy - what spec is terrible on PB+ (3/8 PS 5pc)? I'm reading 17.7kN for the 3 inch version. Better than anything on my trad rack
The rating on the bolt is significantly weaker than most bolt hangers.
Jim Titt
· Joined Nov · Points: 490
Sep 18, · GermanyRyan Jenks wrote:Our two tests broke at 21.50KN and 20.40KN. I'm curious about forged P shape bolts because i like the radius of a solid leg but the weld isn't sufficient to be pulled in tension. Twist legs or double leg styles do flex and stay quite strong but have broken many of my connectors (mostly soft shackles) that should be breaking twice as high but the radius is to small and breaks them before the bolt breaks, which is good for the bolt, but even ropes on the 6mm steel rods (waves and small twists etc) break where the rope bends around bolt and not in the knot reducing the potential strength we could get out of our ropes.
How many people use these bolts in tension? Probably not many, but we have used these to retro bolt the entire fruitbowl area in Moab Utah where we have the GGBY festival and we use hang frames to hold up our anchors to make getting on and off easier, pulling on these bolts at a 45 degree angle, not exactly straight up but unfavorably against the weld. I am in charge of installing the world's largest spacenet which can see forces in the 20kn range on the legs and if BFKs are not tied correctly as angles are hard to guess for nets, the force could be pretty high on a single bolt which is why these results are shocking to me. If the bolt isn't designed for tension, it would be ideal if it was mentioned on the website because we could have done the large twist bolts instead if we knew. Our shear tests have been impressive so I like the Crux Monster bolts, but not in any scenario where they would be pulled in tension. What are your thoughts?
Well cord is tested around a 100mm drum (or something like that) so anything smaller is automatically weaker. For rock anchors where the rope is to be threaded through it should be 9mm diameter.
I measured the weld on a few bolts today after I broke then and it's around 80mm2 so should be holding 35kN on it's own but as I noted that way of pulling is effectively peeling it off. I'll try changing the way we weld which may help but for full strength with an axial pull probably the only way is to change the design which would then be worse for climbing.The primary idea behind the 12mm shaft bolts is having a stiffer shaft for bolts in soft rock so they don't flex so much and crack the rock, for all-round strength the 8mm twisted bolts are better.
C Williams
· Joined Jul · Points: 1,556
Sep 18, · Sketchy, BlackvanistanJim Titt wrote:Apart from Titan Climbing no-one has ever put one on the market as far as I know.
Fixe Hardware sold one for more than a decade. I've used them, mostly at anchors. No idea how strong they are though.
Jim Titt
· Joined Nov · Points: 490
Sep 18, · GermanyC. Williams wrote:Fixe Hardware sold one for more than a decade. I've used them, mostly at anchors. No idea how strong they are though.
Sorry, the European market. They didn't make EN 959 so were only sold outside the EU.
cleatis
· Joined Sep · Points: 110
Sep 18, · Unknown HometownHow about bolts (mechanical and/or glue) placed at various distances (4,2,1") from an empty hole? According to a few people on this forum, the convention spec of spacing a new hole by 10x the bolt diameter is if both bolts are under load. It would be great to test data for the more common replacement scenario of one empty hole and one bolt under load.
C Williams
· Joined Jul · Points: 1,556
Sep 18, · Sketchy, BlackvanistanJim Titt wrote:Sorry, the European market. They didn't make EN 959 so were only sold outside the EU.
Ha! Figures... I can't seem to find specs on them anymore, though I seem to remember a claim of 25kN in at least one direction. I've two left if Ryan and Bobby want to break them. It would be cool to see how this particular design fails.
Shane Brown
· Joined Jan · Points: 0
Sep 18, · Unknown HometownEd Henicle wrote: @ Sandy - what spec is terrible on PB+ (3/8 PS 5pc)? I'm reading 17.7kN shear for the 3 inch version. Better than anything on my trad rack
17.7kn in perfect conditions is terrible for a permanent bolt. Especially when there are plenty of full strength alternatives. Why place something that marginal?
Bobby Hutton
· Joined Aug · Points: 1,153
Sep 18, · Grizzly Flat, CASandy Crimp wrote:I mean the Power Bolt + (a sleeve bolt) not the power stud (a wedge bolt).
The PB+ is the evolution of the ubiquitous 5 piece but it devolved.
These are the PowerBolt + (cant believe fixe still sells these!!!):
https://fixehardware.com/index.php/powers-ps-3-8-x-2-1-4-5-piece-bolt--sd.htmlThe central bolt of the 3/8 is only 1/4, and specs at like 15kn or something. It will be super sensitive to over torque. This bolt was one that Greg Barnes also mentioned above. The original 3/8 PB was so ubiquitous in the US that developers (and Fixe) continue to trust the PB+ despite its terrible specs.
http://anchors.dewalt.com/anchors/products/mechanical-anchors/expansion-anchors/power-boltplus.phpThe PB+ above is only in plated steel. They did not devolve the Stainless version.
That is the bolt we tested. I was also surprised when we got them in the mail from Fixe. I was way more shocked by how high the shear value was. We will pull in tension soon.
Bobby Hutton
· Joined Aug · Points: 1,153
Sep 18, · Grizzly Flat, CAM Hanna wrote: Ryan and Bobby
Thank you for your significant efforts. More testing is always good!!
Big thanks to you for sharing pics and details of your testing rigs. And Jim as well.
Bobby Hutton
· Joined Aug · Points: 1,153
Sep 19, · Grizzly Flat, CAcleatis wrote: How about bolts (mechanical and/or glue) placed at various distances (4,2,1") from an empty hole? According to a few people on this forum, the convention spec of spacing a new hole by 10x the bolt diameter is if both bolts are under load. It would be great to test data for the more common replacement scenario of one empty hole and one bolt under load.
I am currious about this as well. I will see what we can do about doing some sort of organized test. In our concrete slab, we end up drilling into rebar often and had to re drill the holes. I put the new holes close to the failed ones based on a comment that someone made about it only compromising your placment if both holes are under load. Pulling in shear it has made no difference so far. We are only seeing the hole edge crushing in our shear tests before the bolt fails or more rarely comes out. We will see what happens when we start doing tests in tension again as that is when we are seeing large scale failure of the concrete.
Jim Titt
· Joined Nov · Points: 490
Sep 19, · GermanyJim Titt wrote:Well cord is tested around a 100mm drum (or something like that) so anything smaller is automatically weaker. For rock anchors where the rope is to be threaded through it should be 9mm diameter.
I measured the weld on a few bolts today after I broke then and it's around 80mm2 so should be holding 35kN on it's own but as I noted that way of pulling is effectively peeling it off. I'll try changing the way we weld which may help but for full strength with an axial pull probably the only way is to change the design which would then be worse for climbing.
The primary idea behind the 12mm shaft bolts is having a stiffer shaft for bolts in soft rock so they don't flex so much and crack the rock, for all-round strength the 8mm twisted bolts are better.
I changed the weld protocol and started from the shaft end (normally we start the weld inside the eye and work towards the shaft as it's more convenient to hold it that way). Also increased the penetration where the weld joins the shaft to try to stop the peeling effect. The good news I got 59.6, 80.32 and 77.06kN. The bad news is the lowest value was when both the weld and the shaft failed which means I'm starting to weaken it with too much heat or penetration. Got to do some more testing to see what's achievable in production and what it's costing!
Eli Golden
· Joined Aug · Points: 0
Sep 19, · Montclair, NJI'd be curious to look at the raw data as it's generated. I'm an industrial statistician by trade and it seems to me your effort lends itself pretty readily to model-building and data visualization, though the data set would have to be pretty balanced across all conditions of all variables of interest. Testing highly specialized scenarios is useful anecdotally, but tends to create confounding within the larger body of information.
Detrick S
· Joined Jul · Points: 147
Sep 19, · Denver, CORyan Jenks wrote:WHAT WOULD YOU LIKE TO SEE TESTED???
Wow, the free information you guys put out there is amazingly helpful! Thanks for being such a great, evidence-based resource for the community.
I've got a bunch of corroded gear lying around that I'm unwilling to use even though the damage is likely only on the surface. These pieces were left in a cool, wet environment for about 4 months.I've got a bunch of corroded gear lying around that I'm unwilling to use even though the damage is likely only on the surface. These pieces were left in a cool, wet environment for about 4 months.I'd be interested in seeing you break test my variously corroded aluminium and steel carabiners which might help get to an answer of the microfractures /stress-corrosion-cracking question we all seem to be interested in. I'm curious if you all are able to test the breaking strength of cams? If so, I have a few old cams ranging in corrosion level that I'd love to see broken.Cheers!Detrick
Francis Haden
· Joined Dec · Points: 9
Sep 20, · Unknown HometownJim Titt wrote: The only U-bolts I've seen in Europe are one in an artificial crag in Berlin and the ones in the UK, predominantly in Dorset. They are all being replaced. Apart from Titan Climbing no-one has ever put one on the market as far as I know.
Why drill two holes to get a worse performing bolt apart from the problem of them opening the karabiner?
Jim I'm pulling a load of Portland staples around Bristol that I installed 27 years ago when I'm back next month. If they're anything like the ones in the Avon Gorge, they'll be circa 15kN or less
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