Post-tensioned cable release

[@Bear2Roo]

A few winters ago I did a parking structure repair and released several dozen cables...we just took a grinder to it

[@carldinkel5346]

I was working on a 12 storey building in Denver co, when a post tension cable broke lose and killed a carpenter doing wall layout. It was not a good sight. the slab was 12in. thick and tore through the slab like a knife cutting through butter. the guy's doing the post tension cable were stretching the cable when it snapped, no one should have been working near the line to which the cable was being stretched. but it is to late to bring the guy back, it was very sad the guy was 35yrs. old.

[@ristotenno6438]

Thanks! for the story, I appreciate. Was the slab curved, or how did it escape from the slab?

[@carldinkel5346]

Risto Tenno it was a flat slab. they had poured the concrete 4 day's prior to when the accident happened, so the concrete was still in the early stages of curing. It was kind of a freak accident, but even if the concrete is 30yrs. old and let's say a hole needs to be cored through it and the floor is not X-rayed to determine where cables are located, and someone were to drill through one, a person could be killed or injured from a cable coming through the concrete slab. it's pretty rare that it happens like that, but others have done it more than people really know, and it is not a cheap mistake when it happens. usually when it does happen it won't come up through the slab, you will usually here a crack or a snap noise in the slab.

[@J0Gu7]

I call B.S. on these stories. I've been busting through these cables with a jackhammer for years. 60,000lbs per inch tension, and they move 4 inches in a linier direction. The only time they are dangerous is when your dead end is attached to a section thats been weekend and it pops, throwing chunks and drawing in, but it only draws in maybe a foot at most. I work for a company that is always trying to get by on the cheap, and they never de-tention cables if they can get away with it.

[@carldinkel5346]

Caught it Outdoors you can call all the b.s. you want! if your busting through post tension cables with a jack hammer, the cheap ass place you work for better get the hell out of the trade! there is no way in hell you would be using a jack hammer cutting through post tension, unless the cheap company you work for had their heads stuck so far up their asses that they couldn't see day light. your obviously cutting through rebar, and not post tension cables, the general would kick your asses off the job if your company couldn't tell them apart, plus the general contractor wouldn't let anyone jackhammer a post tension slab without having it x-rayed before any type of penetrating began on the slab prior to work being done anyway. p.s. iam not calling you an idiot, iam just saying i have seen it happen on a new poured slab, 6 day's after the slab had been poured. look at an example on KZbin of post tension failure on Florida bridge collapse.

[@sdalarsen]

I am a structural engineer, and also am curious about this accident. Do you have a link to the newspaper article? Typically, once a slab is cast, if you were to cut a tendon, you don't get very much movement in the tendons because of all of the friction in the slab. The tendon might poke out the end by a couple inches is what I typically see. Cutting through a 12" slab like butter also doesn't sound like anything that I have ever heard about. Usually, the way the cables are ran through the slab, they are not near the slab face that they are pushing towards.

[@cxjaguar617]

ive never worked construction or rather deconstruction but id imagine heat is the safest way to release post tension cables cause it give it time to stretch before releasing

[@ahmeddagher]

So this how it looks like when you relieve 3000 Kn of tensile force from P.S cable

[@RadDadisRad]

Anytime i have cut a PT cable it was with a hydraulic concrete saw.

[@cristinaarias9268]

Hi is possible for you talk me about your case i need cut a prestessed beam i will do a support in the middle and after i will cut with a saw

[@365Condoms]

much more fun detensioning 19 x .6'' multistrand head somewhere 20 meters in the air off scaffolding :D

[@jacklaher5065]

They make things like tie-wire and razor knives that you use to cut the sheathing away and then torch the cable.

[@imchris5000]

why waste time doing all that you already have the torch out and its demo so just torch the fucker

[@jacklaher5065]

That's fine if you want to be a Joe! Everything can be done the right way and the Joed up way, it just comes down to the question, are you skilled or are you a Joe?

[@jacklaher5065]

And it still would have been done quicker.

[@imchris5000]

its demo so it does not matter what happens to the cable and no way is it quicker to take out a knife and cut the sheath off then get the torch started and cut or you can just start the torch and cut. he did take forever melting it off though instead of just keeping the flame in one spot and blowing through it. this is the correct way to cut these cables you want your hands no where near a tension cable thats been smashed up with a jackhammer to get rid of the concrete around it. if it lets loose your hand is gone

[@MikeJones-rk1un]

Sorry guys but a hand held, gas powered abrasive saw would cut through that in 5 seconds. Plastic and all.

[@BasedBidoof]

Cool. Is this the only way to do it safely?

[@erikasjankauskas5813]

Based Bidoof there is nothing safe about post tensioning

[@mktwatcher]

What a waste of time and gas - just cut right through the plastic and cable all at once.

[@LosAngeles822]

The cables are very hard to break. You can chainsaw it but doubt it would fit in that space. Or use a pacman cutter but doubt it leaves the cables looking clean like a torch.

[@DukeOnkled]

Lemme tell ya, you do NOT want all the force on that thing releasing all at once.

[@JV-yb1vq]

This thing will cut a car in half if not released the right way, you obviously don’t know what you’re looking at

[@nickmccabe1910]

@@JV-yb1vqi just learned about these today at work. Where can i find a video of one breaking and the tension releasing full force?

[@365Condoms]

wasting gas :D

[@edwithkowski8330]

Cut with a Demo saw quicker an easir!!