Shame the Whipper

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TradMike
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Re: Shame the Whipper

Post by TradMike » Wed Jan 31, 2018 2:14 pm

A fatigue failure is the result of many smaller load cycles vs one larger load. The shown photo was the result of the anchor sticking out just a little too far from the rock resulting in a bending moment in the bolt instead of mostly shear with most bolts. Bolts are great in shear but not nearly as good in bending strength. With repeated falls, it finally snapped into two parts. 99% of the time you will be fine but I wouldn't want to risk it. You can easily generate 1,000 lbs of force in a toprope fall which is enough to do damage on a bad placed bolt. I have seen where they recommend glue-ins to be set into a notch scored in the rock to prevent bending and minimize fatigue from the repeated bending. I have seen some glue-ins that stick out too far. Unless the climber is an expert in evaluating a bolt placement, they may not be aware if it is a time-bomb or not. I have also witnessed a bolt failure during a whip from the top (they said they flamed out though). Just food for though. Keeps you safe.

DrRockso
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Re: Shame the Whipper

Post by DrRockso » Wed Jan 31, 2018 3:39 pm

Tradmike do you have any data to backup your claims? My research indicates top rope falls RARELY generate more than 3kn or 700lbf. As you admit the bolt has to be sticking out from the rock in order to generate these types of fatigue cycles. In all reality you are likely to see a badly deformed hanger before you see a failure of an otherwise fine 1/2 powerbolt or dynabolt gold. Is the picture you posted your own or found on the net? It appears it looks like it was likely in a strange placement and judging by the way it's bent, possibly placed upsidedown. I don't know of any fatigue related failures of glue ins designs currently being used in the red, the wave bolt, and to a lesser extent bolt products style twist bolts, the manufacturer does not recommend notching the rock for these bolts. Though not ideal, we do occasionally come across a glue in where the hole wasn't drilled quite deep enough. I suspect we would see these bend down till they touch the rock far before they would fatigue, though none of the ones I've seen have bent at all. What were the circumstances regarding the bolt failure you witnessed?

TradMike
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Re: Shame the Whipper

Post by TradMike » Wed Jan 31, 2018 4:28 pm

The ASCA says from testing that a toprope fall can generate 1,000 lbs force in the anchors based on testing they did.
link below:
http://www.safeclimbing.org/education/fallforces.htm

I agree most bolts will be fine and rarely fatigue fail but the one I showed did fatigue crack and fail with little noticeable deformation. The bolt was placed in a roof. People kept whipping on it bending it back and forth. Yes, a vertical wall would be more difficult to do this on since the direction will be the same.

My comments are mostly to create second thoughts on how appropriate, or potentially very risky, it is to take a victory whip or any fall for that matter. Why load test something when you don't need to. The soft stone of RRG is also susceptible to failure which is more likely after repeated whips and probably a better scare tactic. I like the mantra that the leader must never fall but that is just me. And if you do fall, it would be nice that 100 different people hadn't whipped on it intentionally. You might be the one it finally fails on.

The bolt I watched fail in the RRG, failed the first inch of rock then bent the bolt 45 degrees or so and then ripped completely out of the wall. I am not saying the bolts in the Red are bad or anyone did a bad job bolting. But, I have seen bolts that look perfectly normal most of the time but water flows out of them during a rain. What is going on inside the rock in those types of situations? How sound is that rock? Looks good from the wrapper, may be fine, maybe not.

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