Climb ZA Forum | South Africa Climbing & Bouldering

Hello,

I'm new to this forum and not sure if this entry is right here. However, I think that your experience
in the area of rope attachment could be very helpful for an upcoming project, which will be taking place in a disused cooling tower
(89 m diameter). In the broadest sense, the planned installation is similar to a slackline / highline setup.

First of all a few basic info about the structure:
The intended use involves the use of the inner cooling tower concrete cladding (concrete grade not known, probably > B35)
for the purpose of restraining an approximately 2m installed at 3 suspension points in
17 meters height through three slackline-bungee cord-icosahedron joints. The icosahedron construction will be located in
about 5 m height in the cooling tower center.

For the basic clarification of the structure, I have attached a picture.

The first purpose of the setup is to climb inside the icosahedron structure and create a vertical bouncing of the system in the amount of
several meters by body centering displacements.
You could use a harness in combination with a slackline leash and climb or maybe walk on the line to reach the icosahedron structure from one of the three suspension points. Because of the cooling tower structure, it is difficult to reach the suspension point, therefore a slackline leash makes no sense. So for the cooling tower I will use a rope ladder to climb inside. For the next year I plan to install the structure in a
cliffy environment, thus a slackline leash could become very effective.

My actual question relates to the planned attachment to the cooling tower concrete wall and whether it is reasonable or stable enough.

The icosahedron construction (40kg empty weight) weighs about 150 kg with me and additional equipment and should form an angle of about 15 degrees to the suspension points. The tensile forces
should be more or less 2 KN for each of the 3 suspension points. As a result of the dynamics generated, the tensile forces could increase up to 4 KN.

In the upper area (17 m height), four Fischer FAZ II M12 / 30 anchor bolts should be placed at each of the three suspension points
(the boreholes are approx 25 cm apart) in combination with bolt tabs and M8 quick links connections. Due to the four quick links connections, a 10.5 mm static rope should be guided through two M12 delta quick links (50KN) and be freely movable. Each strand is then about 80 cm long. As a connection node a triple or fourfold fishermens knot is considered. In addition, each rope strand is to be secured by means of a 16 mm sling loop
via a figure 8 follow through knot as a back up system. Maybe I could use one long tape and bring all tape strands to a central point and tie a big figure of 9 on the bight(loop) as a backup system, because it will have more regular strands.
By the two delta quicklinks two slacklines (the second slackline serves as a backup) are deflected, starting from the icosahedronto a steel plate near the ground (25 cm x 30 cm x 0.8 cm, fixed with 4 Fischer FAZ II 12/30 anchor bolt on the Cooling tower wall) by means of
two Gibbon shackles (50 KN). As Weblocker I will be using lashing buckles (breaking load 50 KN). Because of the slackline
deflection, the upper fixed points in 17 m height are more loaded. The advantage however results from the better handling
during clamping. For an assessment, I would be very grateful.

many Greetings

Frank

The rope rescue standard Static System Safety Factor is 10:1, to allow for dynamic events. Whatever your static load is, your system needs to be capable of withstanding 10x that static load. With 10.5mm low stretch rope, you're looking at 28-30kN unknotted, and 14-15kN knotted. You'll need to have double or triple strands in places to have sufficient SSSF.

Resparachute wrote: ↑Wed Dec 05, 2018 6:07 pm

Wandhalterung_oben_S2.jpg (91.46 KiB) Viewed 6784 times

While this looks cool and might work on the ground, unloaded, I can tell you from experience (and considerable testing) that these self-equalising systems do not work, all they do is create the potential for extension and shock loading should one anchor fail. You'll be better off tying off the master point using a BFK.

Another option is to use load-limiting devices, such as the Petzl I'D S 2, the ISC D4 and others that will slip reliably at a certain load, to ensure that your loads cannot reach dangerous levels

To avoid the extension that Nic is talking about (although you have already catered for that with your tied off webbing?) you could use the sliding x/ whoopie method that we use for high-lining. That way the sliding x equalises sufficiently, and once under tension you nip up the whoopie slings. That way if one anchor point or the sliding x fails, there is no extension in the system. Whoopies can be made from 6mm dyneema. This is a similar form of redundancy to what you have done with the webbing in your pic, but more adjustable and super strong. Thats the method we use anyway

Thanks for your reply.
Tying a master point using a BFK could be a problem in this system, because the tied master point in my setup will shift to a new unknow position when the slackline will be tighten from downside. So this was the reason, why I have chosen the self-equalising system with the sliding x/ sling rope method (a whoppie sling as Kieran said would be better). But you are right, from what I have researched today, there is no automatic equalisation. Nevertheless, you can manipulate the system with some outer force after loaded, but this is neither an elegant nor precise method. Anyway, going back to the upper point in 17 m heigth and control the shifting master point more or less synchron while tighten the system would be impossible. Do you have a link for the other option with the Petzl I'D S 2,I have no idea how this will work?

Many greetings

It looks like there are enough dynamics in this setup that consulting a professional to do a site inspection and advise you properly, is best advised.

- High-Angle
- Venture Forth
- Skysite

and many others could help you.

Ant

Resparachute wrote: ↑Thu Dec 06, 2018 5:10 pm Thanks for your reply.
Tying a master point using a BFK could be a problem in this system, because the tied master point in my setup will shift to a new unknow position when the slackline will be tighten from downside.

If all your bolts/anchors are in a horizontal line, and the load is only moving significantly in the vertical direction, the the change in vertical direction will not change your anchor loading, so a BFK would work.

Resparachute wrote: ↑Thu Dec 06, 2018 5:10 pm Do you have a link for the other option with the Petzl I'D S 2,I have no idea how this will work?

https://www.petzl.com/INT/en/Profession ... Descenders

Basically, attach the I'D S to your anchor, pull the rope from your load through it, up to your starting tension. Leave slack in the "dead" (non-load) side of the rope. When people are bouncing on the system, if the peak load exceeds the holding power of the I'D S, the rope will slip through the device, reducing the load and preventing the system overloading and breaking.

Thanks for your reply,

I thing the BKF method with the anchors would work fine for me. Nevertheless, if I understand the system with the petzl ID´s right, I need a Petzl Id´s für each anchor. So when I am intendinging to use 4 anchors (and I won´t use less), I need 4 Petzl ID`s for one suspension point and in total 3*4=12 Petzl Id´s, who are fairly expensive. In general I liked the idea of rope equalization but as you said it won`t work properly. Is it in general more effective to use 4 single and two double roles to reduce the friction? I have a pulley system for my slackine, so I have made a picture to show you what I mean. For the backup you could use whoopie sling as Kieran said before.

Many Greetings

Little update,

I have finished the project and had no problems with the concrete of the cooling tower. For the upper anchor point in 20 m height I decided to use a steel plate. Here is a photo of the plate setup and a videolink about the project https://youtu.be/jGoxwGmDrRA


Thank you for the given tips.

Many greetings

Frank

Looks like a fun project! Good work

Sorry, missed your follow up post.

You'd only have needed one I'D for each of your three anchors since you're trying to keep the forces in the legs going to the cage low.

Even with pulleys, you're unlikely to get proper equalization. There's been some fairly extensive testing done on this and it really is a nice idea, but fails to work in the real world.

Looks like you solved it anyway. Now you just need to suspend the guy inside the cage so that he can invert...

Thank you for the feedback.

Many greetings from Germany

Frank