Glue-in Bolt Test Results at Muir

[dhoyne]

what a good discussion.
Dhoyne- In your opinion (noted that, as you stated, you haven't test Corbin SS, yet) would rock, Corbin SS, be prone to fracture and possibly ultimately fail secondary to cyclic loading if no movement was introduced between the bolt and the stone, i.e. the bolt was immovable in the hole?
Thanks

Good question, and I'm undecided in my answer. No movement implys that the bolt isn't yielding at all, which is very seldom the case. There's usually a tiny bit of deflection when the bolt is loaded; not within the hole but at the head of the bolt. If there truly is no movement, then the force that applied is below the yield points of the bolt and rock, and only an extremely tiny amount of wear is put on the system. But everything will eventually wear regardless of force -- otherwise the Grand Canyon wouldn't exist.

Picture a bolt like a lever. For this example we'll assume the bolt is horizontal and the rock face (and therefore force) is normal to it. As a weight is applied to the hanger, that end of the bolt is pulled downwards. The most stress is seen at the bottom of the bolt where it first enters the rock. The rest of the bolt (the part in the rock) is then being pushed upwards -- it's basically trying to rotate around that one point. Of course, the bolt is firmly attached (hopefully) to the rock, so all that force is dissipated thru the rock along the length of the bolt. The deeper the bolt goes into the rock, the better it will dissipate the force, to an extent - there's an exponential decay in force as you get away from the fulcrum of the lever, but that's not a topic for this discussion.

Now take into account what Rick stated -- no matter how good you are at drilling, the hole is going to be wallowed out a bit. That enables the bolt to flex just a bit at that interface -- and there's where your cyclic loading failure can occur. The bolt is flexing at the same point again and again, which will eventually weaken it. As this is happening however, the bolt is crushing against the rock -- if the rock is soft, the hole can open up more because of this.

Is any of this occuring on a grand scale? No. Otherwise bolts would be popping out all over the place.



Ho -- I want to test it just out of curiousity. I've never seen any data on compressive strength of this type of rock before.

[Cliff Heindel]

You have a personal grudge against something that really is a non issue, and I think you are the irresponsible one. Why not start a crusade against something that might actually be dangerous, like not stick clipping the first bolt.

Wes-we should start a crusade against whiners. We can joust demagogues of non-issues into submission with our righteous
stick-clips of glory then hang them from the first bolts as a warning
to infidels.

[the lurkist]

thanks for the feed back dhoyne.
A follow up then.
Is it possible that the system of Corbin SS and a properly placed 3 3/4 Mechanical bolt (Rawl,redhead, dynobolt gold, etc) is much stronger (perhaps the term over engineered could be used) and resists the torqueing forces of repetitive falls to the point that minimal wear is evident (neglible wear accumulates) after many years of use? Is there a real concern of failure with this system with repetitive long dynamically caught/belayed falls?
While I know there is no science concerning this yet (pertaining to Corbin SS anyway), I can think of a fairly large sample set (>50#) of bolts that have seen this type of use for 12-13 years and most are still slammer. This bolts I speak of are at the Lode. The most glaring examples are the last bolts on the Madness Cave routes. To get off of these routes with a 60 m rope the obligatory fall from the anchors has been customary. Of course, many other of these bolts on these routes and routes on the Undertow wall see a huge number of long falls every year, and I believe most are in good shape and most are orginal gear. (This is not an arguement for taking VW, but more a desire to understand the disconnect between what has been observed at the Lode and some of the concerns voiced in this thread regarding the threat of repetitive falls causing bolts to loosen and then potentially fail catastrophically).

[jimtitt]

Hi there, it´s me again from Germany (I´m a Brit by the way) I have posted the rest of my stuff on www.climbargolis.com (bolting) with a review of glue-in bolt design, you will have to translate some of the units into imperial (how I love writing that to Americans!). Up in the NE of Germany in the Elbe sandstone area where the rock is very soft they use 150mm bolts with polyester glue and get good test results. For you guys 1/4" AISI 304 stainless Bühler bolts would be the choice in a loose 1/2" hole, actually the looser the better. If someone sends me his E-mail adress I can send you some sketches of how to make a bending jig and anything you want to know. the prices quoted are European stainless prices, check out a local supplier. obviously a longer bolt will cost more but probably only around +25%. Any help you need then contact me.
P.S. While your on climbargolis check out climbsicily and see where 600 bolts went in the last couple of weeks!
Jim

[the lurkist]

Jimtitt,
wow, that is an incredible resource. thanks for sharing.
I did not see all thread mentioned as a stock material for glue ins.
Is it too antequated, pull out strenghts too low...?
It seems like it would be a cost effective material. Obviously the lower off quality is lost. Maybe that isn't such an issue with single pitch sport climbs?
Your thoughts?
A Yank's thanks from the colonies.

[Saxman]

Where has this happend? I have done several tests about this and would like to see more data.
Thank you for any additional info.

The data is the couple of times it has happened with witnesses and been reported to the climbing mags or online.

[goodguy]

rockman wrote:
Where has this happend? I have done several tests about this and would like to see more data.
Thank you for any additional info.

Im not sure but I seem to remember a story of a girl who was slammed into a low roof while using a gri-gri. She was knocked unconcious, the gri-gri was pinned to the roof and the climber was dropped and if memory serves, killed. I think this was 2 or 3 years ago. Maybe someone else remembers.

[stix]

Think about it, if the belayer is off the ground after a fall and opens up the grigri, who gets lowered first. The belayer. We do it every time we give a soft catch. The same happens when a grigri get smashed into the first draw (assuming the belayer doesn't have ahold of the brake hand). This happened to me a couple of years ago on twinkie. This tiny canadian girl (bout 95-100lbs) was belaying me (180lbs) and was nervous about catching me, so i figured i'd show her it was fine. I got to the chains and pulled up a couple of armloads of slack and jumped off without clipping. She got yanked into the first draw jammed the grigri open, she slid down till her brake hand got pinched in the device, she let go, she got sucked back into the draw, jammed the grigri open again (this time without her brake and on), she got dropped on her ass, and i got one of the nicest soft catches ever.

See nothin to worry about

[2tall]

Stix. I think your full of shit. no offense but if a belayer gets pulled into a roof and the climber is falling at full speed then the force of the climber falling will just continue to pin the belayer to the roof.

Also, why would you ever do something like you did to a belayer who is already freaked. Im sure she felt much better about belaying after getting her hand pinched and being dropped on her ass. Way to go, Dooshbag.

[rockman]