Triaxial Loading

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What is triaxial loading: What does the term mean, where is it encountered and why is it often a concern? For bonus points: Explain how you'd circumvent the issue.

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Questions will be judged/commented on by @egilson1 and @What Rigger?

Thanks to @RonHebbard for suggesting the question.
 
I mean, Belden does spec a max recommended pulling tension of 124 lbs. I imagine the stranded version is higher... This is what we really have so 264 lbs of pull tension, give it a 10:1 safety factor and you can hang about 25 lbs from it without damage!
Oh, and always a bowline.

(For anyone thinking this is serious - No. Don't. Please.)
 
Somehow this discussion reminds me when our tour u haul truck brok down and we towed it with a length of 12/3 SJ cable
 
I mean, Belden does spec a max recommended pulling tension of 124 lbs. I imagine the stranded version is higher... This is what we really have so 264 lbs of pull tension, give it a 10:1 safety factor and you can hang about 25 lbs from it without damage!
Oh, and always a bowline.

(For anyone thinking this is serious - No. Don't. Please.)
Where's that Double LIKE button?
@eadler
Thanks for your tongue in cheek reply, clearly better than coax with BNC's and FAR superior to solid coax with F connectors.
@What Rigger? @egilson1 @FMEng and @Ancient Engineer Would you care to play along?? PLEASE!!
Toodleoo!
Ron Hebbard
 
Somehow this discussion reminds me when our tour U haul truck broke down and we towed it with a length of 12/3 SJ cable
Understood and appreciated. Did you by any stretch employ two lengths of SJ and anchor them with ONE ( Singular ) carabiner??
Toodleoo!
Ron ( with my tongue so firmly in my cheek as to likely require surgical extraction. ) Hebbard
 
Since it's been enough time and nobody has answered, its 3 points of loading under tension, most problematic with a carabiner, (see the providence Ringling Brothers accident where a carabiner that was triaxially loaded broke, and dropped a bunch of people) though you can do it with shackles as well. In the case of the Ringling incident, they had 2 pear rings on a carabiner which caused it to break. The osha findings cited that a shackle would have abated that. With a carabiner, the strength is inline with the spine, so a triaxial load spread that out at an angle and therefore distribute the load in a way that lowers the overall strength of the carabiner and puts stress on it.

As far as I know, nobody recommends or says doing this with a carabiner is safe.
 
It's a complicated issue so safe to say no, but I believe some common climbing situations require tri- and quad-axial loading.

shorturl.at/ehlzW

As this report shows, the ultimate strength of the triaxially loaded biner is less than when properly loaded in line with the spine, but not substantially.

Generally, I try not to rely on biners. Don't load a biner other than (bi)axially unless you really have done the work. And I think most of the time that work is finding the worst case impact. When it all goes fubar, what is that impact? Requires a lot of education and mentored experience to calculate that.
 
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It's a complicated issue so safe to say no, but I believe some common climbing situations require tri- and quad-axial loading. https://www.blackdiamondequipment.com/en_US/qc-lab-off-axis-tri-axial-carabiner-loading.html
As this report shows, the ultimate strength of the triaxially loaded biner is less than when properly loaded in line with the spine, but not substantially.

Generally, I try not to rely on biners. Don't load a biner other than (bi)axially unless you really have done the work. And I think most of the time that work is finding the worst case impact. When it all goes fubar, what is that impact? Requires a lot of education and mentored experience to calculate that.
Uh, Bill? Your link's not working for me.
Toodleoo!
Ron Hebbard
 
Uh, Bill? Your link's not working for me.
Toodleoo!
Ron Hebbard
Prior to posting the current QOTD, @dvsDave included an excellent video in a PM.
I'll try to cut 'n paste it but I may not be successful. @dvsDave could post it if my cut 'n paste is unsuccessful.
I found a great video on triaxial loading done by Chicago Flyhouse, Inc!


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Toodleoo!
Ron Hebbard
 
Your math is wrong. A bowline reduces the strength (of rope) by about 1/3 so the maximum load would be about 16 lb or about 7 kg for every country other than the United States, Myanmar, and Liberia.
To be fair, if I were to actually want to do this and have the cable come out usable, it'd probably be less than a pound of force before it pulled the cable tighter than the minimum bend radius with any knot or hitch (short of putting hitches around a 279.4mm or larger O.D. pipe). If I actually wanted to do this for loading and not care about the ~$10/m cable, I would go through the spec sheet and account for the breaking strength of the various insulation and jacket materials and likely find a much higher rating -- the maximum pull tension (1174.320 N) is a spec for maintaining the cable's ability to meet the specified electrical characteristics - essentially at this pull strength the cable will not deform (or will deform 'evenly' across all layers/insulations/dielectrics).

Step one of course for this exercise is to place ones tongue firmly against a cheek.
Here's the metric spec sheet in case you want to do some real math :)
 
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Toodleoo!
Ron Hebbard

Shoot me a Private Message if you are still showing this error.
 

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