Back to front page.
CragX Index :: Rebolting NSW :: Testing of Rock Climbing Anchors
Who's Online :: Stats :: Memberlist :: Top Posters :: Search
Welcome, Register :: Log In Welcome to our newest member, Flano.
Users active in this forum:
Users active in this thread:

people online in the last 15 minutes - 0 members, 0 anon and 0 guests. (Most ever was 74 at 04:51:16 Sun Oct 28 2012)

Pages: [ 1 2 ]

[ Notify ][ Print ][ Send To Friend ] [ Watch ] [ < ] [ > ]

phm
11:29:45 Fri
Sep 29 2006

Offline
34 posts
Outdoor Climber

Reply
Testing of Rock Climbing Anchors

Maybe the following reference is of interest to some people on this forum:

Pircher M. (2006) “Testing of Rock Climbing Anchors”, Journal of Testing and Evaluation, ASTM, v34, n5, pp 416-422

Another one on the Design of Rock Climbing Anchors is in the pipeline.

  
shawkshaw
13:07:24 Fri
Sep 29 2006

Offline
1343 posts
Administrator


Reply
Re: Testing of Rock Climbing Anchors

how do non academics go about geting hold of this paper? sound like it could be great.

  
rogerb
01:13:01 Tue
Oct 3 2006

Offline
151 posts
Flash Specialist

Reply
Re: Testing of Rock Climbing Anchors

Ask the author for a PDF. That journal is not available from Uni of Sydney and I couldnt find the paper on google scholar.

Either way, I think I've read it and the testing methods didnt match real rock very closely.

The big unknown in real rock is the bond between the rock and the glue and to a lesser extent between the glue and the bolt. Unless the rock is crap (in which case the bolt shouldnt be there or needs to be 500mm long) 90% of the TLC needs to go into maximising the bond of the glue to the walls of the hole and making sure there arent big air bubbles inside the hole.

That unknown is the main thing that worries me in bolting.

  
phm
09:56:38 Tue
Oct 3 2006

Offline
34 posts
Outdoor Climber

Reply
Re: Testing of Rock Climbing Anchors

Ah c'mon Roger. Why don't you at least pretend to have read the paper before dissing it...

I am pretty sure you will find the journal in the engineering library at USyd (under number 620.11205 3 according to the library website) or most other Unis in NSW. Otherwise google spits out the following link:
http://journalsip.astm.org/JOURNALS/TESTEVAL/jte_home.html

There is a problem with copyright laws when putting the paper in a public spot. Private copies are a different matter, though.
[1 edits; Last edit by phm at 15:57:07 Tue Oct 3 2006]

  
rogerb
23:02:20 Tue
Oct 3 2006

Offline
151 posts
Flash Specialist

Reply
Re: Testing of Rock Climbing Anchors

Mmmmm. Touchy! Perhaps its not the one you showed me a couple of years ago with bolts glued into concrete blocks of various composition? Anyway, I wasnt dissing the content. Cant you send Steve and I a PDF of the new one? Nobody has time to go to the engineering library to photocopy it.

  
phm
06:38:41 Wed
Oct 4 2006

Offline
34 posts
Outdoor Climber

Reply
Re: Testing of Rock Climbing Anchors

pdf copy sent.

  
rogerb
02:15:47 Thu
Oct 5 2006

Offline
151 posts
Flash Specialist

Reply
Re: Testing of Rock Climbing Anchors

Very interesting paper Martin. Especially:
"It was shown that an anchor in soft concrete [=sandstone] can exhibit the required strength through a number of loading cycles and then fail".

and (paraphrased): "you cant assume an anchor is safe because everybody falls on it".

The obvious conclusion is that we should make crux bolts stronger than bolts that are loaded only rarely.

What is the opinion of the engineers on the best design for such a crux bolt?

1) Since failure in soft rock seems to occur progressively from the front of the drill hole, would a better design be a long hole drilled diagonally up (assuming that the steel is stiff enough to distribute the load all the way to the back of the hole)?

2) Is a U-bolt more suitable for a crux bolt than a welded ring?

  
petey_w
03:31:56 Thu
Oct 5 2006

Offline
127 posts
Flash Specialist

Reply
Re: Testing of Rock Climbing Anchors

Havent read the article, but assuming that we are talking about failure of the rock (ie crushing at front edge) then IMHO the answers would be:
1) yes
2) yes

  
shawkshaw
04:25:05 Thu
Oct 5 2006

Offline
1343 posts
Administrator


Reply
Re: Testing of Rock Climbing Anchors

roger can you send me a copy.

steve at climbinganchors.com

  
phm
09:51:02 Thu
Oct 5 2006

Offline
34 posts
Outdoor Climber

Reply
Re: Testing of Rock Climbing Anchors

The cyclic loading test was interesting indeed. The good news is, that all anchors that failed after a relatively low number of cycles looked progressively 'bad' during the test. In other words, "if a ring bolt looks dodgy, then it probably is dodgy."

I would prefer to take the obvious conclusion a bit further: We should design bolts in a way that they don't display this failure mechanism at all.

I have a principal problem with U-bolts: reliable bond between the bolt shafts and the glue is a lot harder to establish for U-bolts than for P-bolts. P bolts that are twisted into the fresh glue usually bond very well. U-bolts that are 'slided' (or hammered) in tend to bond unreliably. This was observed under lab conditions and would probably be worse in real vertical life.

Drilling bolt holes diagonally upwards leads to a different loading situation all together - shifting the emphasis from shear to pull-out. I agree that this approach would probably alleviate the "crushing problem" but might lead to other problems - such as putting greater stresses on the glue-rock interface, another problem area as Roger has already pointed out. However, I have not done any tests on inclined anchors.

  
shawkshaw
10:13:51 Thu
Oct 5 2006

Offline
1343 posts
Administrator


Reply
Re: Testing of Rock Climbing Anchors

thanks for the copy martin. ill have a read but looks interesting at a glance.

  
hatman
21:53:12 Thu
Oct 5 2006

Offline
568 posts
Rock God


Mood Now: Overworked
Post Mood: Hysterical

Reply
Re: Testing of Rock Climbing Anchors

hmm, has anyone EVER seen either type fail in the feild, ie: someone took a whipper and the bolt failed due to any reason??

I know of quite a few ring bolts placed incorrectly (no notch) however even they still seem to be ok.

Sure you can get them to fail in a lab test but under real worse case scenario wots the chance?

  
tnd
22:51:01 Thu
Oct 5 2006

Offline
61 posts
Lead Climber

Reply
Re: Testing of Rock Climbing Anchors

Hatman's got a point. I haven't seen the paper under discussion, but thinking back to Steve H's study, bolts were failing at no less than 15 kN. I would have thought most lead falls would generate no more than 5 kN. That's a fair margin of error in the real world.

Agree about U-bolt glue distribution being problematic. I try to be really careful when placing them, buttering plenty of glue on to the legs before sliding them in. Do others think this is the right procedure?

  
tnd
23:05:56 Thu
Oct 5 2006

Offline
61 posts
Lead Climber

Reply
Re: Testing of Rock Climbing Anchors

Another option is to use the half-inch stainless reo embedded about 30cm like Mikl did on Fox Sox Pox at Berowra...

  
rogerb
23:56:00 Thu
Oct 5 2006

Offline
151 posts
Flash Specialist

Reply
Re: Testing of Rock Climbing Anchors

According to Martin's paper his research was inspired by several failures in the field. I know of one (at Narabeen??) where Martin was the load that caused the failure.

  
bundybear
00:26:48 Fri
Oct 6 2006

Unavailable
1322 posts
Net addict - someone take me climbing


Reply
Re: Testing of Rock Climbing Anchors

I think the bolts also pulled out on a fall at Elanora. This crag would be supa if it was rebolted and safe again. Anyone ??

  
phm
08:27:37 Fri
Oct 6 2006

Offline
34 posts
Outdoor Climber

Reply
Re: Testing of Rock Climbing Anchors

In addition to the one "field test" which Roger mentioned (and which inspired my research), there are several other ring bolt failures that I know of. Some of them overseas, but some also in Oz.

A number of first bolts on climbs also show clear signs of rock crumbling away underneath the ring, quite similar to the first onsets of failure in the cyclic tests which I could observe in the lab.

Factor 2 falls generate well in excess of the 15 kN mentioned above. And that's not taking into account a safety margin.

"Buttering" the U-bolts was certainly practised for our tests, still we could not get the same degree of consistency in performance as for Ps. Fig 10 in my paper supports this.


  
bolter
09:54:37 Thu
Oct 12 2006

Offline
1 posts
Climber Wannabe

Reply
Re: Testing of Rock Climbing Anchors

You might also like to look at www.climbargolis.com bolting for some info on european tests and ideas.
Bolter

  
rogerb
02:13:26 Mon
Oct 16 2006

Offline
151 posts
Flash Specialist

Reply
Re: Testing of Rock Climbing Anchors

Martin, your Fig. 10 suggests U bolts are generally much better than other designs in soft rock (and its what you'd intuitively expect). I agree about the problems of getting good glue contact but I'm not convinced that this is impossible with a U bolt if you make sure it is a loose fit in the holes and wiggle it into the glue. Hammering any glued bolt in is crazy. It just gouges out a pile of fresh rock from the side(s) of the hole and ensures a crappy or non-existant bond of the glue to that part of the hole.

A bit of research on glue would go a long way towards improving anchors. How about treating the hole with something that makes the drilled surface more glueaphilic? Or using a more rockaphilic glue. Or both.

  
rogerb
02:14:45 Mon
Oct 16 2006

Offline
151 posts
Flash Specialist

Reply
Re: Testing of Rock Climbing Anchors

I attached a JPG of Fig. 10 to the last post but apparently the server has run out of space for attachments.

  
Cragx
03:02:32 Mon
Oct 16 2006

Offline
2055 posts
Administrator


Mood Now: Jamming
Post Mood: Jamming

Reply
Re: Testing of Rock Climbing Anchors

Email me the piccy and ill upoad directly to the server roger, admin@cragx.org

  
Cragx
06:01:39 Mon
Oct 16 2006

Offline
2055 posts
Administrator


Mood Now: Jamming
Post Mood: Jamming

Reply
Re: Testing of Rock Climbing Anchors

Heres the piccy


  
Glenn_Short
09:20:07 Mon
Oct 16 2006

Offline
48 posts
Outdoor Climber

Reply
Re: Testing of Rock Climbing Anchors

Hi there,
G'day Martin! Gotta throw my 2c worth in here.

The "buttering" of Us seems to have always been a dodgy practice in my books. (Your fall Martin??) All the manufacturers state that anchors should be twisted into the grout. I've spoken to a number of their engineers and they stressed that cleaning the hole, using threaded rod and twisting the anchor in are the main ingredients for success in setting anchors. Hammer in capsules are made to overcome the problem of not being able to twist some anchors into glue where spin-ins can't be used. The epoxy used is much runnier than injection glue, with the idea that it "runs" into the threads.
Injection glue doesn't do this. According to the engineers I've spoken to this leads to quite a few failures in the field. Earlier this year I was at Ramset when two of their consultants were there after a second visit to a building site where anchors had been buttered and pushed into injection glued holes (because an attached plate prevented rotation). The anchors had failed, resulting in a wall collapsing, they eventually changed the design to allow rotation on one and used hammer ins on the other.

Mind you, I also think that mostly the glue and anchors are so overkill that they'll be more than good enough for climbing. Still, being a devout coward I still ponder the ones that just might fail...

(I am also pretty sure that the old carrots I've broken off with a ring spanner were much dodgier)
Just butter em up really well boys, I'd hate to get hit in the head by a falling u bolt after I've hit the deck!

Cheers

Shorty


  
hatman
20:21:35 Mon
Oct 16 2006

Offline
568 posts
Rock God


Mood Now: Overworked
Post Mood: Vengeful

Reply
Re: Testing of Rock Climbing Anchors

so to draw some sort of conclusion.

P type 10mm rings when twisted in and notched properly, look like the best type of anchor.

U type 10mm anchors are very strong (strongest?), however every efort must be made to get full glue coverage. (don't forget that U's have two legs)

trad anchors are super crap as they use no glue at all.

Intersting to note that some of the comercial anchors didn't not do so well on the chart.

So I will go on trusting both U bolts and rings as the chance of faliure of either is so low that I am not worried. And I will in the future use ring bolts on new routes, mainly because i have hundreds of the suckers.

I have to point out that getting a "loose" fit in the holes for a U is nigh on imposible. Getting the holes paralel is not easy when hanging on jumars 10m off the ground. In fact the U bolts are sometimes used in overhanging teritory because of the tight fit, so they don't fall out before the glue cures. In my experience a tap on the U is needed most of the time to get it in the last bit of the way.

[2 edits; Last edit by hatman at 20:25:02 Mon Oct 16 2006]

  
Breezey
00:20:20 Tue
Oct 17 2006

Offline
43 posts
Outdoor Climber

Mood Now: Retro_Hippy
Post Mood: Retro_Hippy

Reply
Re: Testing of Rock Climbing Anchors

Would someone please email me a copy would be interested in reading this further.

breeze at bridgeport.com.au

thanks

  

Pages: [ 1 2 ]

[ Notify ][ Print ][ Send To Friend ] [ Watch ] [ < ] [ > ]

 Total Members: 2104, Newest Member: Flano.

  • Can't start a new thread. (Everyone Registered)
  • Can't start a new poll. (Everyone Registered)
  • Can't add a reply. (Everyone Registered)
  • Can't edit your posts.(Everyone Registered)
  • Register :: Log In :: In Power

    The time is now 13:31:55 Sun Oct 20 2019

    Powered By BbBoard V1.4.2
    © 2001-2007 BbBoy.net