I kept waiting for it to break, and send a splinter through Blue Hat's forehead.

Fuck it

don't you get it? these dudes live on the edge...

Maybe, but you have to remember that the load press is designed to stop applying load once a certain yield is reached. so at final failure, the load was removed. In a real application the load would have continued to be applied, until free fall of the bridge.

It's a controlled pressure. When the samples break, the hydraulic machine stops.

It was purposely designed as an under-reinforced or balanced design beam. Which means the steel tension reinforcement yields first (and slowly), before the concrete in compression. If it had been over-reinforced, the concrete would have yielded explosively before the steel reinforcement and should be avoided for obviously reasons.

popogast who won the pot?

same here haha

Yeah, that's helpful for anyone still using neanderthal units.

@@Kalumbatsch like me

Wait, did you put an extra 3 in there by mistake in the last one or am I stoned? Not mathing well right now 🤣

Also I i think it is 18.3 tons if anyone is interested and doesn't want to type on a search bar 🤣 Again I may be wrong and just being dumb as shit 😂

I was wondering 💭

And without safety shield or safety glasses.

Ahh it's ok they went to university lol

Was thinking the same thing, the clap at the end is then all being like “yay we didn’t die on this one, next one boys”

Two days is not long enough for a bureaucracy to get moving. I am sorry, it probably cost lives.

This is pre-stressed concrete, not reinforced concrete. The beam has internal cables which have a designed load applied to them prior to casting the concrete. These cables have placed the surrounding concrete in a "super-compressive" state and are absorbing the tensile load at the bottom of the beam. A standard reinforced beam would have failed sooner and more dramatically.

Well it isn’t painted so your incorrect.

Plus, as I recall from my own destructive testing days, heavy hammering with one of dad's best by ten/eleven year old boys (later I may admit to penny testings on the rails).

Episodic spalling shrapnel events are fairly uncommon beyond teacup saucer range, I expect.

😑yep

Not sure, a square hollow though is extremely strong as to the way it transfer forces around and I only know that from randomly watching a KZfaq vid yesterday that was explaining some inherent failure in I beams. Might be worth searching with those search terms. I wonder if it had tensioned steel cables within.

Maxwell Goodacre o

Yes... we saw.

Ty

Thanks

Maxwell Goodacre Which is the best crack?

Same thoughts i am having ..sheesh

I guess they know that steel bends and concrete gets smashed with no flying objects...

lol

@@refuztosay9454 ?

neeeeeeeeeerrrrrd

Its normal thing for reinforced concrete. There is no fail at 66kN. Concrete cracks because it can't handle tension, but rebars can handle tension.

@@SAIGUK More accurately, because it lacks the elasticity of the steel rebar.

​@@nairdacharles9492 Can't agree. Concrete has elastic modulus for tension and compression. Elastic modulus is nonlinear. But concrete cracks only because of lower ultimate tensile strength.

Almost certainly steel reinforcement springing back and pulling it back into place. Wood also does this, by the way - when it loses moisture horrible looking cracks start to appear, then when the moisture content goes back up it seals back up perfectly like they were never there.

It's safe...

And one is walking around..

*no safety glasses

Eh no these lads are what you call invincible gobshites

Yes , if you know what you doing.

@@bahn5ee but you dont know what you're not doing.

You mean paint it and ship it lol.

I noticed that too. These boys are playing in the sandbox but they've not experienced the jobsite.

It’s concrete it just crumbles

It was not their first beam. That day.

it crumbles and much safer with the gradual force.

This is what engineers do when we are bored. Frack it'..................Lets go break something in the test lab!

It teaches us the limits of materials. That's why nobody who has some experience with engineering and construction can, in the right mind, believe the official story of 911 and the collapse of the WTC buildings.

gowd sake you basically wear what the main guy in charge wants to supply

They had helmet.

I totally agree with you E Murphy I am a retired Ironworker and have experience stressing cables in parking structures and have seen blow outs a few times.

Old dude in chair was chillin’. No biggie.

Explode? Not in concrete that crumbles in a gradual force om a lab.

@@romeoETmike those post tension cables can easily fling concrete pieces in a split second. I have seen it happen with my own eyes.

Don't forget your shear and bending moment diagrams.

Smart ass

Don't forget the sexy elastic curve.

I think we all know this is missing a crucial axial force diagram

Yeah

Thinking the same. Testing with that type of energy near by waiting to release. Brave men they are. No shields, no eye/body protection, a computer station set a few feet from the test, wow. No OSHA there I guess.

why is everyone such a prick about safety? osha standards cause about as much damage as good old common sense. i knew a guy installing fire protection in a hot attic with the safety "dood" for the GC nearby and he could barely see the sweat was building up on the inside of his glasses and the safety "dood" didn't care. the glasses stay on. thats epitomy of the problem with osha, the same problem that engineers have. they all want to keep their jobs but the only way they can is by impeding the flow of common sense. they are not your eyes! perhaps they have already tested cobcrete beams and they KNOW there is no EXPLOSION DANGER. people that comment safety fails are the same people that would eventually have us wearing ppe just to watch dangerous videos...

No safety at all. Why the hell they were clapping?

What the hell do you know about how reinforced concrete behaves during a steady load yield test anyway? I sure don't because I'm only a mechanical engineer by training. So I assume you all are civil or structural engineers then? And you guys did research on dynamics of energy release during failure of this material? No? So let the experts in their own field decide for themselves! Smh*

Brains...

Was also surprised by lack of containment. Was wondering if I was even correctly understanding what they were doing.

It doesn't matter if OSHA approves or not. This isn't their jurisdiction. Also, those engineers knew that it was not going to be an explosive failure. The debris all fell within a 1.5 meter area directly below the failure. Nobody was closer than 3 meters to the beam during the failure event.

@@bob2161 Don't be silly

@@tomsreviews238 how is my reply silly? Are factual observations silly to you?

Don't need safety shields for concrete, the moment the material gives.. The pressure is gone.

If it makes you feel any better, this was a contest between engineering schools to find the best design for a certain set of parameters. We will never know if it was a success or not because we do not know the results of the other teams.

It's over six minutes of watching it fail and I'd say that's slow enough. 6:12 it is in slow motion and shows the break.

Concrete crumbles and slowly if force is applied gradually.

It does not fall down or explode when it cracks trough. the load is released because it's a press and not an object on top ☺️

Stop crying

@@shortthrow50 it's a comment not a dick....don't take it so hard

holy shiit!

and the beam was shaped with the load points in mind.

@@MrZoomZone Not 'shaped' enough then.

@@FairladyS130 it would depend on the design load. Perhaps this was already 200% of the3 design, so it performed well at that point.

So long as you're not inside the beam when it implodes, you're golden.

Maybe they just seem to understand the nature of these reinforced concrete failures just a tiny bit better than you? Possibly? 👀😎

@@stevendegreef93 Maybe he understands the benefits of managing risk just a tiny bit better than you? :)

@@stevendegreef93 If you ever stressed post tension cables you would understand how dangerous and unpredictable a blow out can be.

@@shanesooth6267 Those are springs. Free steel under tension. Completely different animal. In this case all steel has been encapsulated with concrete, there s just no way that all tension on the steel can be released at once. Or does your imagination see all the concrete letting go of all the embedded steel at once? (footage contradicts you) (you must be right, these engineers are soooooo dumb.... 😆)

@@stevendegreef93 you don’t need to be a smart ass behind your keyboard. I may be wrong but from what I read in the description it says nothing about a encapsulated steel beam it’s does say prestressed concrete beam. I have built similar beams for DSI when I was a local 416 IRONWORKER in Los Angeles. I am retired after 31 years placing rebar.

The whole idea about designing safe concrete structures is to avoid catastrophic failure. A well designed concrete part is going to greatly deform before eventual failure of the compression zone (this is beautifully shown in this example actually). The whole idea about this is that it gives of a warning effect leaving time to evacuate the structure when it is overloaded or failing. When a beam instantly breaks, it could indeed be a lot more catastrophically!

It also has to do with how the load is applied. Unlike a hydraulic press or something where the force is always applied, here, the force is applied because the block is being driven down by giant jackscrews at slow, fixed rate. It couldn’t shoot down even if it wanted to

in real life the load is distributed on wider span, it's not the missile falling straight down; even truck standing on the road distributes the load between front and rear wheals

Right. I understand that this tests an extreme, and I understand there is a point to that but some more realistic testing would be quite interesting to see, as would other extremes, like a full spread of the pressure application. I'd imagine a beam like this would be able to take a fair amount of crushing force before it just collapses. I wonder how these would do with say, 100 feet of earth on top of them, used as the ceiling of a bunker. Too many edibles tonight.

@@HitLeftistsWithHammers Actually there isn't much difference as far as the failure mode of this beam goes. The loading model for point loads vs linear loads is somewhat different but in the end it comes down to exeeding the compression capacity in the top or tension capacity in the bottom. That being said structures are always designed according the normative loads that are to be expected. (e.g. an column on a beam or floor could be represented as a point load wheras everyday use or snow is represented as a linear or areal load)

@@casb2480 That's interesting to me. This isn't the same, but I'm reminded that the service strength testing of fire department ground ladders was accomplished by the application of point loads rather than distributed. My knowledge of that subject is quite dated, but here is a picture of current testing procedures, so it's done the same way now. www.ul.com/services/fire-department-ground-ladders-testing

@@elizabetholiviaclark also, for the sake of practicality; it’s far easier to do testing like this as opposed to applying linear loads

Clint Hymes No fucking shit. What's with people's need on KZfaq to point out the fucking obvious?

as a matter of statistics the beam would yield at a higher force than in this test with a single point of force. These different tests are called three point and four point loading. The reason that four point loading gives a smaller number is because it tests a larger area of the beam for a fault which causes a large enough stress concentration. It can be counter intuitive but when it comes to ceramics like concrete two loads half the size are more likely to cause a failure than one load that's twice the size.

Like your need,..... and what you just did?

Well spotted, it might be. My OLED TV has something called pixel shift, what you see here might be that in action.

Thats why you have two eyes. In case you get one poked out.

@@HiltownJoe Concrete doesn’t poke.

yes exactly

I agree. Noticeable first failure was at the turn in the beam, had it been straight the possibility is it would of took a far greater load, despite the loading position.

@@adrianbew9641 That’s why the beam is reinforced there. Yes, it would have carried a larger load if it had the thicker cross section along the whole span, but then your beam is heavier, harder to work with, takes more materials to make, and is more expensive. And if the bridge only needed to carry 75kN, then they’ve got a decent safety factor there, and designing a beam that can handle 300kN is wasteful. Anyone can make a bridge that stands, but it will almost certainly be more expensive and use more materials than is needed. It takes an engineer to build a bridge that only just stands (with a factor of safety, obviously), and uses only the minimum required amount of material.

first thing I thought too, they must not have OSHA in Canadialand.

That would be less stressful.

This test is called four point loading. The reason why it is used is we can accurately determine the area of the beam which has experienced peak stress and extrapolate from there (all points in between the two loads on top experience an identical bending moment). Essentially what this is doing is identifying the statistical probability of locating a significant stress concentrating fault in the beam. Counter intuitively this form of test will cause the beam to fail at a lower force than a test with only one point of loading (as a matter of statistics) and applying an even load over the entire beam would only complicate the results by removing the convenience of a constant bending moment over a known area. Instead, there would be function of degree two to describe the bending moment over the beam, rather than degree zero which, if I remember right would mean the test would suggest the beam would be stronger if the load was evenly applied over its length. Also it would be much more of a pain to run calculations with

so its a simulated test with the results calculated and scaled up to full size with the end result total failure and this way ensures the easiest way to achieve that? my next question is wouldnt 3 point loading be easier to calculate and if the stresses too high ,couldnt you just scale down the beam ?

It's not simulated - as you can see that test is the real deal with an actual concrete beam. The most important result is the flexural strength of the concrete which is a pressure so it doesn't have any bearing on how much concrete is actually there. From the strength and a known area of concrete you can find the force a beam can withstand so they could be scaling or they might not be to trust the results more. Yes, this test is the easiest way to achieve this goal. Arguably 3 point loading is easier like you suspect and the beam could be scaled down if their rig can't exert enough force. The reason why four point loading is preferred is because it is much less likely to accidentally overestimate the strength of the concrete because in a real environment the beam may experience four point loading which causes the beam to break more easily than a three point loading test would suggest.

derp man ok sounds good

i had to go re-watch.. but yeah that is kind nutty..? maybe something to do with refresh and the camera?

Probably a plasma or other technology that suffers froms burn in and has a technology to shift the pixels a bit in order to prevent burn in

the steel is flexible

I did this in 8th grade.

@@edwardcornell1263 I did this before my first birthday.

Maybe they used to do it and decided that kind of work was too miserable.

D. Ryan Shaw i tried to look up what "kn" stood for before i commented and it was way beyond my ability of understanding. But i would think it was far greater than that?

Jeff Williams I believe a kilonewton is around 220 lbs of force or so. My line of work requires equipment that is rated at 23kn's or greater and I'm pretty sure that's right around 5000lb's. So 1 kn would be about 220 lbs

Christopher Green a void, improperly placed contact pads, or other unexpected causes of point stress could send a small chip flying. A large chunk falling and hitting the bed would also have plenty of energy to send a chip flying. Large pieces won't get flung around the lab, but it doesn't take much to damage an eye, and rated safety glasses are cheap protection.

--Yes! You are absolutely right and eye protection (and ear) education ought to begin at a very early age--long before people enter adulthood let alone the workforce (any kind of education in anything might be a nice goal too, but that's a different video). As is sometimes the case, the comments to this video were kind of more interesting to me than the video, which is the reason why I dove into the physics, statics and dynamics, etc. and a more considered comment would have included your points as well. That said, allow me to reinforce your message: one day, as a young machine shop apprentice, I saw an old fashioned safety poster from the sixties (I'm from the sixties!;) with an actual photo of an actual person with a piece of a shattered 3/32" HSS twist drill literally sticking out of his eyeball--after that day I never "went without" my glasses again. That image worked for me far better better than any amount of drilling (pun intended of course) so I must also include another "picture" of my friend, a bookstore owner, who lost her eye to a bungee cord hook while securing a stack of books to a cart. Stretching it out and down, perfectly aligned with her face, it slipped from her grasp and in an instant took out an eye--and I mean out. Your point is well-taken Robert, thank you. When injury and 1/2 m(v)^2 go together, it's usually the v that does the damage.

that is all you can do is criticize video parts. arent you special

@@wildkatsailing He knew it won't explode, it just crumbles.

I believe there was a rapid change in tension sensor reading.

And the crack formation happens are very high velocities

Tell you what, most of standards that you are talking about are made by these kind of people.

Demolition (brute force) is much different than gradual force like in this lab.

@@romeoETmikeanother internet troll who thinks he knows it all. I have seen concrete explode under compressive loads. You'd be the same a****** who would complain about me not using jack stands in an auto repair video. Go f*** yourself

It's wasn't needed for that kind of test. But you do see the guy closest by the screen put them on at one point.

First thing I noticed. I've never seen a work environment where a hardhat is necessary but safety glasses aren't, including this video.

Brendan Boyer Construction sites (if no one is working), some factories. There are many places. Eye protection is only need if there is a risk of eye injury.

They're highly unsorted engineers

SchizoidMan does that also mean they are well graded?

China is making half the constructions in the world and all them fail, yeah