I've been trying to find the answer to a question but the amount of anchor topics is overwhelming. So I bring up one more.

Consider 3 protection points @ 10kn each
A fall directly on the anchor with no belayer and capable of ripping any anchor
The sling/cord breaking strength is not a factor.
Lastly for the sake of argument the self equalizing anchor is perfect.

1 A self equalizing anchor where the outer 2 legs are 90 deg apart & equal length.

2 An anchor with a tied power point, 90 deg outer legs and center leg is somewhat loose

3 Imagine pro orientated horizontally and a PAS type sling is used to connect the pro in series and the rope is clipped to only one end. Forcing one piece to completely blow before the other even sees any load at all.

What is the ultimate load each anchor can take before it collapses completely?

I've been trying to find the answer to a question but the amount of anchor topics is overwhelming. So I bring up one more.

Consider 3 protection points @ 10kn each
A fall directly on the anchor with no belayer and capable of ripping any anchor
The sling/cord breaking strength is not a factor.
Lastly for the sake of argument the self equalizing anchor is perfect.

1 A self equalizing anchor where the outer 2 legs are 90 deg apart & equal length.

2 An anchor with a tied power point, 90 deg outer legs and center leg is somewhat loose

3 Imagine pro orientated horizontally and a PAS type sling is used to connect the pro in series and the rope is clipped to only one end. Forcing one piece to completely blow before the other even sees any load at all.

What is the ultimate load each anchor can take before it collapses completely?

Theoretically speaking...

Scenario #1: +24kN
Scenario #2: +14kN
Scenario #3: +10kN

... or so.

Do these scenarios ignore energy dissipated by the failure of each piece of protection? For example, in the third scenario, blowing the first piece of protection takes 10kN out of the system. That energy is mostly used to stretch the rope (assuming this factor 2 fall is on a rope). So is it the case that a rope tensioned to 10kN and given no time to recover will break the next piece of protection no matter the load at this point?

The numbers make sense to me if the anchor is stressed by a pull tester which can maintain a constant force, but they do not make sense in the case of the anchor arresting a fall.

1.) Is there time for rope recovery (to absorb more force)?
2.) Is there extra fall distance, so more energy/velocity into the system?
3.) How does the piece fail -- how quickly? Does it snap instantly? Does it drag out, crumbling rock as it goes, taking a bit of time, but with a reduced force load over that time? Some combination of the above?

Do these scenarios ignore energy dissipated by the failure of each piece of protection? For example, in the third scenario, blowing the first piece of protection takes 10kN out of the system. That energy is mostly used to stretch the rope (assuming this factor 2 fall is on a rope). So is it the case that a rope tensioned to 10kN and given no time to recover will break the next piece of protection no matter the load at this point?

The numbers make sense to me if the anchor is stressed by a pull tester which can maintain a constant force, but they do not make sense in the case of the anchor arresting a fall.

Do these scenarios ignore energy dissipated by the failure of each piece of protection?

Yes, we ignored all that because the original scenario specifically stated the fall was capable of breaking any anchor, thus you can dissipate as much enrgy as you like in any way you like and it won´t effect the inevitable failure of the three proposed anchors.
I was a bit hasty giving acorneau a +1 as he shouldn´t really have put the + in front of 10kN for scenario 3, maybe a +0.9 was in order but at least he knows it is written kN so can have the other 0.1 back!

I wrote "+10kN" because each placement can hold 10kN then you need more than 10kN to break it.

10.0000000001kN would work... theoretically, of course.

Yes, we ignored all that because the original scenario specifically stated the fall was capable of breaking any anchor, thus you can dissipate as much enrgy as you like in any way you like and it won´t effect the inevitable failure of the three proposed anchors.
I was a bit hasty giving acorneau a +1 as he shouldn´t really have put the + in front of 10kN for scenario 3, maybe a +0.9 was in order but at least he knows it is written kN so can have the other 0.1 back!

Sorry guys I did mean to take into account energy absorbed by a rope. I should have picked a lower kn for the anchors seeing as any roped fall will be held by 1 pro.
Assume a rope is in the system and it's rate to 11kn impact

My theory is the anchor 3 would fail @ +30kn and the other two slightly less because of the angle between the legs.

Again sorry for not being clear from the beginning.

Sorry guys I did mean to take into account energy absorbed by a rope. I should have picked a lower kn for the anchors seeing as any roped fall will be held by 1 pro.
Assume a rope is in the system and it's rate to 11kn impact

My theory is the anchor 3 would fail @ +30kn and the other two slightly less because of the angle between the legs.

Again sorry for not being clear from the beginning.

Theoretically speaking...

Scenario #1: +24kN
Scenario #2: +14kN
Scenario #3: +10kN

... or so.

Thanks! I was forgetting the time it takes the rope to spring back. No wonder it sounded weird.

Scenario #3:
1st piece fails @ 10kN
rope regains .1kn [ let's just say ]
2nd piece fails @ 10kN
rope regains .1kn
3rd piece fails @ 10kN
Anchor fails @ 10.2kn

Am I understanding this better??

What you have to understand is that while a piece may hold 10kN the energy involved to break it can be minimal. Substances are either brittle or tough and climbing gear no exception and rock in particular. For a cam to ping off a limstone flake is easy and takes virtually no energy out of the faller whereas a cam ripping at 10kN load down a perfect crack from top to bottom of El Cap will require an enormous amount of energy, more than can ever be supplied by a falling climber.
So you approach the problem by calculating the energy available, remove whatever energy is used in the failure (google `energy of fracture´ as a starting point as this is technically what it is called) and then recalculate the force the climber will impose on the next piece. Best of luck!
For sequential failure of protection then you whizz through http://amga.com/...al_Failure_Paper.pdf
Best of luck there as well!

So if the pro rips when the rope has 5ft of stretch [10kn].
I regain the energy it took to stretch the rope from 4.5ft to 5ft assuming I had 6 inches of slack between pro.

I would need 2 meters of slack between the pro to go back to square 1. Assuming the rope could recover it's properties back instantly.

Who would have thought that a 11kn fall would rip out 30kn worth of protection like that

EEk, back to step one!
The rope applies a force onto the cam, the cam applies a force onto the flake, if there is enough force the stress (force per unit area of the material) exceeds the strength of the material and it breaks. The energy required to do this breaking depends on the material, a good steel takes several hundred times more energy to break as concrete for example. A steel karabiner with the same breaking strength as an aluminium one would take roughly twice as much energy to break, this is why some materials are known as tough and others as brittle. How much force is taken out of the fall depends on how much energy was removed by the flake breaking, not the force required to do so.

The energy from our tracking cam would either be friction or the work done to gouge the rock out or rip the aluminium off the lobes, probably a bit of each at a guess!

This type of cascade failure is, among other reasons, why many of us have objected for years to the standard cordelette as a universal method of anchoring.

Now let's say the leader falls on the anchor with a fall sufficient to generate 12 kN of force. What happens?

And because a picture is worth a thousand words:

[image]http://i47.tinypic.com/34q08kl.jpg[/image]

GO

Let's see if I understand. 2 carabiners both rated @ 10kn. One very brittle the other very tough.
I drop a heavy weight attached to the carabiner via a stretch-proof cable.
The weight breaks both biners. The difference is the brittle biner absorbs nothing because it just snaps like a potato chip. The tough biner will elongate and therefore absorb energy. The weight still hits the floor but with less force, energy or speed just fill in the blank.

Now if I replace the cable with a bungee cord. Won't it absorb energy as the brittle biner is breaking.

And because a picture is worth a thousand words:

[image]http://i47.tinypic.com/34q08kl.jpg[/image]

GO

Do I read correctly in that AMGA paper that they were using static (<5% stretch) ropes for these drop tests?

[image]http://www.mountainproject.com/images/85/55/106368555_large_c48104.jpg[/image]

If i got to an anchor and saw this and survived, said partner would never leave the ground with me again. Theres do the best you can with what you got, been there many times. And then theres sketch . . .

There are exponentially worse anchors out there when it comes to hard aid climbing.

Two points on that.

1 that's what bolts are for. (FYI I'm no sport wanker, bolts have their place)

2 hard aid scares the shit out of me and doesn't l look like fun. (And I firmly embrace type 2 fun) if the rock is too soft for bolts, it's too soft to climb. (And yes I have been to Moab, used a scary five bolt anchor and had a great time)

As anther primarily trad climber, I agree with your first point. And your second. But there are guys out there who have their fun hanging off of nothings, and some of the things they do are insane.

If i got to an anchor and saw this and survived, said partner would never leave the ground with me again. Theres do the best you can with what you got, been there many times. And then theres sketch . . .

Upon reaching the logical belay point, I whipped out my drill and started drilling a ¼” hole to place a 1.5" belay bolt. We were running very low on good drill bits as lack of financial stability was unanimous and expending money into drill bits didn’t take precedent over visits to the mountain room bar prior to leaving on our granite voyage. As a result were in the habit of starting the hole with a dull bit and then breaking off the tip for a fresh, sharp edge to drill with. After 25 minutes of non-stop drilling my sad little hole was only ¾” deep.

I was loosing patience and tired of drilling so I yelled down to my partners, Jim Bridwell and Dale Bard, “let’s not haul from here, let’s just climb through and fix ropes. It’s taking too long to get the bolts in and I’m out of bits. Is it ok to belay off off 5 equalized rurps and a rivet?” Although this may seem ridicules [sic] the seam that the rurps were in was harder than a W*****’s heart and quite solid. Besides nothing like that had ever been done before to my knowledge and the pure novelty of it … I thought. Thankfully Dale strongly protested, as he would be the one cleaning the pitch so I slogged on and put in a 1” bolt, still very substandard for a belay, and backed it up with a rivet. The drilling must have taken an additional half-hour.

I knew that when Dale reached the anchors it would be an amazing photo op so I brought up the camera on the tag line and got positioned. Unfortunately it was so windy that when the time came one of my aiders blew up into the image and there was no way to stage his reaction so that’s why there’s this big blur in the photo behind his head.

I'm not questioning the pro. In a picture like this I can't tell if those are rurps or knifeblades. What I'm questioning is how the pro is strung together. The series clove hitch method seen in this photo has been superseded by multiple other anchors that equalize and allow no extension if a piece fails. Climbing trad on limestone choss has taught me that overall, you want to spread the load between multiple pieces and also most importantly as mentioned above, allows minimal extension. For example, if each of those pieces would hold 5kn, and were subjected to 7kn load, each would fail in series. However if equalized, 5 pieces at 5kn could hold 25kn in a perfect environment. In the real world because perfect equalization is impossible, the sharing would be less than ideal. However if each holds 2kn and one gets 1kn, our 7kn is absorbed.
Disclaimer
If poor equalization occures and the weakest/highest loaded piece fails, the remaining pieces can share the load and the anchor holds. Not to mention the fact that inan anchor with low extension the piece that fails will probably just slip a bit until the others become loaded more.
2nd disclaimer
I'm sure one can find a way to make any ideal (or lest than ideal) anchor setup fail. My point still stands, if you don't know how to build a better anchor of good or bad gear better then cloving them in series, I'm not climbing with you anymore unless you learn how do do it better.