So I am trying to solve a problem, I’ve done a simple solution but I want a more comprehensive answer and don’t know how to do the math.(adsbygoogle = window.adsbygoogle || []).push({});

The problem involves climbing anchors and the difference between max loads of an equalized vs non equalized anchor.

The two different situations, I’ll try to keep as simple as I can and still represent likely real life scenarios:

1. An anchor with 2 points perfectly equalized.

2. An anchor with 2 points but .5m of fall between anchor points, meaning that the load of a fall comes down on one anchor point until that point breaks, then there will be a .5 meter fall before the load comes down on the second anchor point.

What I’m trying to figure out is how much more total force can be expected from #2 vs #1 in a fall that generates 15kn of maximum load in #1

I did the basic calculations (f=ma) and the additional force is negligible:

I assumed a 100kg weight falling an arbitrary distance to generate a force of 15kn. Each anchor point breaks at 10kn.

In #1 the anchor doesn’t break.

In #2 the first anchor point breaks at 10kn (dissipating the force as heat in the components) and the second anchor point experienced a load of 5kn plus the force of 100kg falling .5 meters (~100n)

For 5.1kn force, and the second anchor point does not break.

Where I get lost is the fact that the rope stretches (and recoiles) and the disparity that that causes, which I do not understand.

According to an online force calculator for climbing rope falls (That presumably factors in rope stretch)

http://ferforge.tripod.com/Srt002.htm

The force generated by a .5m fall is .5.6kn to 11.25kn depending on the length of rope Resulting in a force of at least 10.6kn and the second anchor point breaks. This doesn’t apply to the problem precisely because, I assume, it is calculating an acceleration from 0m/s to 1m/s with the rope unstretched.

I would expect that there will be no significant additional load but I don’t know how to work it out, and the online calculator seems to suggest otherwise, I’m stuck here. I don’t understand where all the extra force can come from.

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# Help calculating maximum loads

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