Beam Test...watch beam failure in slow-motion!
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- เผยแพร่เมื่อ 20 ก.ย. 2024
- Each year, the Precast/Prestressed Concrete Institute (PCI) challenges students to design, fabricate and test a prestressed concrete beam. Each beam is judged on a number of criteria including cost, efficiency, practicality and accuracy of predicted behaviour. Teams from all around the world compete in this international competition. The 2014 team from the University of Toronto includes Rami Mansour, Amos Chen, Karl Shao and Xi Li. The rectangular, variable depth beam is post-tensioned with harped strands.
For the test, the beam was supported at it's two ends with two incrementally increasing loads at midspan. It is interesting to note that the majority of the beams deflection occurs after then steel tendons have yield. In addition, the explosive failure is a result of the concrete crushing at the top of the beam.
I'm amazed at the lack of safety glasses and people being so close.
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...
Everyone in the comments apparently works for osha..
I got to work in one of testing labs at NIST (fixing the elevator). They were testing highway support pillars for earthquake designs. They also were testing a keel design for supertankers. Watching a 30' x 8' round concrete pilar twisted and shaken till it failed was very interesting. The keel test was not as dramatic. Made me appreciate all the talent that engineers and architects bring to our everyday lives.
I'm impressed that the beam failed in a controlled manner and never actually completely fell down. If this had been in an actual bridge, the cracks and deflection would likely have been noted and the bridge closed long before there would have been loss of life. Even at the end with massive deflection, the bridge would still not have fallen.
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.
I initially thought it was a steel beam until it shattered
same here haha
Ladies and gentlemen, a round of applause for the hydraulic press operator!
I like this procedure. When I studied some decades ago, we students were given the task to estimate the load when first cracks appear, the deflection at this load and the maximum load the beam would bear. We were given all the information of the continuous rectangular cross section, reinforcement and cube strength and E-module of the concrete. We also had 2 point loads. 4 weeks after casting we could watch the experiment like the one shown. It was very illustrative as we found out, that the formulae worked very good.
popogast who won the pot?
66 KN is 14,877 pounds
156 KN is 36,070 pounds
163 KN is 36,644 pounds
if anyone was wondering.
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 💭
aha, no safety screens
Quite literally the slowest - yet most entertaining video I've seen this year.
The bridge that collapsed in florida had stress cracks on its underside and it was reported by an employee 2 days before the fall.
Two days is not long enough for a bureaucracy to get moving.
I am sorry, it probably cost lives.
Tons of force on something that will catastrophically fail, and sitting right next to it. Unbelievable
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”
Wow, as strong as 163 Fig Newtons! Man, that's a lot!
Did this beam 'win' because it was most cost efficient, held the most, lived up to the predictions best, easy formation, some weighted combination? Explosive failure wonder whey there is no shielding?
Hey I worked for coreslab Structers for almost 7 years! It was amazing the stuff we got to erect that came from the yards that were made of concrete.
My first concrete beam design project in college asked us to come up with an optimal profile, cross-section and steel reinforcement for a simply supported beam of specified span, to carry a specified load. I came up with a profile quite similar to the one being tested here ie. with a deeper cross-section at mid-span than at the ends. I was surprised however that most beams in practice (like those across highways) have the opposite profile, with deeper ends than at mid-span. Apparently, engineers in practice are more concerned with resisting shear forces at the ends than bending moments at mid-span.
I have so many questions. What's in the beam? Steel rebar? Tensioned cables? CFRP? What's the concrete made from? Does it have additives? What's the criteria for the test? Looks super fun.
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 TH-cam 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.
That was a lot more deflection before failure than I was expecting for concrete. The steel must be really stretchy, relatively speaking.
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.
So they just sit around the beam with no safety equipment, no eye protection.:. But hats off to the whoever welded those damn carts!!
Episodic spalling shrapnel events are fairly uncommon beyond teacup saucer range, I expect.
Pressure from the mother in law.slow at first and then the cracks in the paint start to show.never ending pressure until collapse.
Well it isn’t painted so your incorrect.
Thought that paint would never dry!
😑yep
It's good to see critical, load bearing construction materials being subjected to such testing.
Lives depend on the quality of these beams.
engineer: i think i can improve this beam a bit..
beam: haha... that cracks me up..
I’m no engineer but is it a good idea to be sitting next to the beam being tested?
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.
Yes, that looks like a safe environment to be in with 163kN loads until failure.
Same thoughts i am having ..sheesh
I guess they know that steel bends and concrete gets smashed with no flying objects...
Spent two years of my engineering internship at the Portland Cement Association Structural Research Lab, the reinforced concrete equivalent of the PCI. While we designed, constructed and tested all manner of bridges and buildings I think my favorite was developing a reinforced concrete railroad tie. The tie not only must resist the zillions of cycles of the wheel loads but freeze/thaw and high temp cycles, abrasion from the ballast, side loads absorbed on curves and braking load must be considered. And to think I took them for granted.
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).
I'd love this job, especially seeing all the different types of failures. I've seen ones on glass before and that was a smashing vid.
So even after it cracked and failed at 66kn, it still supported over 150kn and even with many cracks it stilled held strong. Until at least 163kn
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.
First crack @ 2:00
Close up of 5 large cracks @ 3:35
Major deflection and ultimate failure @ 4:57
Major deflection and ultimate failure up close @ 5:50
Best @ 6:13
Maxwell Goodacre o
Yes... we saw.
Ty
Thanks
Maxwell Goodacre
Which is the best crack?
I wished I'd've known about the Toronto Big Beam Contest during the COVID shutdown. I'd've sat for days watching the beam tourneys, 2014 through current, on the big screen in my living room.
lol
@@refuztosay9454 ?
neeeeeeeeeerrrrrd
Surprised to see the lack of care precautions for the risks to people around in a destructive load test like this!
It's safe...
this is my alma mater although electrical eng. but you would have lectures in this building and from an upper floor there were large windows where you could look into the main lab. they were always testing something either concrete or large wire ropes as thick as your arm to failure. this was back in the early 80's so yah i'm old. i'm sure things have changed there in 40 years. at that time the contest i remember was a model bridge with a span something like 3 feet. and materials were mostly anything . the winner was the one with highest strength to weight ration. so most of the models were wood/ composite.
Why no personal protection equipment?
They had helmet.
So was that a good test or a positive test or a result they were looking for because I feel that is 7 minutes of my life ill never getting back.....
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.
5:50 beautiful how concrete cracking can close without leaving a trace
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.
Ship it before it gets too noticeable.
You mean paint it and ship it lol.
This shows why u have to under reinforce your beam ... So that the rebar yields first and there is ductile failure
LEFM is a magical thing. When this video started I already knew where the cracks would form
Quick, Bob, put some spackle on that before the inspector shows up...
the suspense is killing me
High tech ,fully equipped, state of the art , crack analysis right there.
Where is the slo-mo section of the video?
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.
Naively, I had it in my head that in this type of testing all human structure in the test zone was removed to a far distance per civil engineering standards - foolish me.
At 04:25, when "orange helmet/blue t-shirt man" pushes the cardstock? under the beam while under test to sample fallen material - quite interesting - can they forecast the inevitable destructive collapse that accurately?
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 ☺️
Cool, during the fast forward bit you can see the burn-in protection on the TV slowly shifting the display.
Safety thinking = alien concept
You forgot to draw your free body diagram.
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
We all love to watch stuff break.. It's important.
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.
That was neat seeing the way it flew apart at the top when it finally reached compression failure... Thanks for sharing.
Is the monitor doing that to prevent burn in? It's wiggling up and down
Well spotted, it might be. My OLED TV has something called pixel shift, what you see here might be that in action.
Under that much stress it's possible something could fly off. Surely the operators would be safer in an elevated position and further away.
It’s concrete it just crumbles
It was not their first beam. That day.
it crumbles and much safer with the gradual force.
Main cracks started at the two load points, who wudda thunk.
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.
That's why It is ideal that the design of beam is tension controlled
So much tension, but at the end, the operator is positively beaming.
I wonder what the failure would have been if the weight was applied evenly across the center, not across two 6 inch(?) 4 inch(?) wide areas a few feet apart.
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
is the monitor randomly moving the image to prevent burn-in?
yes exactly
I like the smattering of applause at the end......jolly well done beam!
I like the way they all have hardhats with fuck all to fall on their heads and yet no screens between them and the beam
gowd sake you basically wear what the main guy in charge wants to supply
That's a solid win for them. Great job guys!
It's all cool and educational until a piece of concrete goes flying and hits someone in the face.
Concrete crumbles and slowly if force is applied gradually.
wow no safety shields on utm 🥵
Don't need safety shields for concrete, the moment the material gives.. The pressure is gone.
I was expecting a more catastrophic failure.
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
Welcome to the hydraulic press channel, and here we go,
holy shiit!
yeah, Im just gonna sit here 5 feet away from this fkn thing, no containment devices, nuthin but a hard hat.....till it implodes, really
So long as you're not inside the beam when it implodes, you're golden.
Thats only like 35000 lbs of pressure, if I'm not mistaken? I thought a beam that thick would be able to handle a much more significant load. What kind of application is this beam designed for?
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
Questions guys,
1. for a prestressed beam, does it really need to have a bulge or deep cross section at the middle in order to have a higher bending moment capacity or load rating? Beam of this shape seems to have no beauty mah.
2. So when the strands broke, the beam went kaboom ?
3. In a real bridge, when a small crack is observed at the bottom of the beam, does it mean that the bridge should be condemned?
4. Vidcam you used in the test, how close to the test subject and what danger of being hit by the concrete pieces on explosive failure ?
***** In any beam of any material, having a deep midsection like the one in this video will determine the overall strength and longevity of the beam. It seems like you might understand the concept of what I'm talking about, but think about a ruler standing on its side. You can bend it, but not much. Now add a second ruler standing the same way to increase the depth. It's nearly impossible to break when you try to bend. In terms of a crack in a beam/column on an actual bridge, only severe cracks will determine whether the bridge will need to be condemned. Small cracks could mean anything. As long as the bridge is under similar loading at all times, the crack should remain the same. If the bridge is in severe weather conditions, any crack is a problem. Cracks can be fixed fairly easily. Like any structure, maintenance needs to be done. As long as the student is standing a good 10 feet away, there won't be a problem. If your beam is exploding, then your construction is definitely questioned. I think a bolt failure on a steel beam could definitely cause damage to someone no matter how far away they stand.
+Ozzie Wozzie Original -- you were reading my mind with these questions
The deeper the belly on the concrete beam the stronger it will be since the neutral point will be able to shift deeper into the beam. concrete being ~ 12 times stronger in compression than tension. Not sure if that helps with your question.
This reminds me of how a steel rod is put into guitar necks, at a curve. Then it tightened to straighten out the neck, which would otherwise bend due to the tension of the guitar strings. When the curved rod is tightened, it wants to straighten, and this gives the "underside, if you will" a "lift". The greater the curve, the greater the lift.
Ozzie Wozzie Original im not a smart man by any means but im assuming the purpose for tests like this is to put a structure under a much larger load then it would ever see under practical use, much in the same way osha tests safety equipment? Am i wrong?
My question to you is do you think the beam would perform better if you filled it with self expanding foam or something to that nature?
How did you know when the first crack formed? Can't see squat
I believe there was a rapid change in tension sensor reading.
And the crack formation happens are very high velocities
Why is the screen of the sitting guy moving a bit, like the dvd idle logo?
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
Good thing it was recorded in slow mo..... the video finished just as I woke up. Good timing.
literally no one is wearing safety glasses lol
I noticed that too. These boys are playing in the sandbox but they've not experienced the jobsite.
2:20 the guys head in the chair moves funny. Too much excitement for me there!
Say no to crack.
When Beam fails, switch to a nice single malt
Bizarre lack of containment around this beam. Concrete failure of these beams during stressing is not unusual and can be explosive in nature with large pieces of concrete being expelled at high velocity. This is not a hypothetical safety issue. It's a real and extreme danger that any stresser will tell you about.
For those of you questioning the lack of safety glasses and PPE. No amount of of PPE will save you from a baseball sized lump of concrete travelling at 100mph.
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.
And I bet you would take even more load, if it wasn't for the tiny contact area of those 2 blocks with sharp corners biting into the concrete and really concentrating the load. I assume it is calculated to be there and in this manner. Impressive either way.
You know who else would take even more load?😏
@@droppoint495 As your name suggests :D
That would be a different test.
The beam failed under each point of force. I'd like to see this test and how it would react with one point of force in mid span.
Clint Hymes No fucking shit. What's with people's need on TH-cam 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?
Love this content... subbed... go for it. The world needs more engineers! Our bridges are crumbling.
Yet somehow we manage 25mil for gender studies in Pakistan, 20 mil for the effects of downed trees in forest, and 20 mil for for office furniture, among other things. While, as you pointed out, bridges are crumbling, infrastructure is is hanging on by couple strands, and our vets are sleeping on concrete. How did we get here? (Rhetorical)
Engineers are going to be hard to come by when are children our taught 1+1=3 because reeecist. Take it easy man
What we need is more bridge builders. One engineered can design a bridge and use it a dozen times albeit modified to the conditions. It takes a LOT of workers a LOT longer to build just one.
No safety glasses, no protective barrier between the test equipment and the desk and monitors... Seems these "engineers" are ignoring BASIC safety concepts.
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.
It's interesting the way the cracks are fairly evenly spaced across the beam. On in the middle, then one about eight inches on either side and then another about eight inches on either side of those. Is this a sign that the strength of the beam is very uniform across?
You don't need to be a safety officer to see the observers are way close. Wow
Stop crying
@@shortthrow50 it's a comment not a dick....don't take it so hard
Did someone notice how the picture on the screen is moving around? Is this a camera issue or a screen feature like burn-in prevention?
Play with Junk No. That is the substance you are using 🤣
Way to go guys! Looks like you all were wearing the correct PPE during the test. I was hoping a small shard of concrete was going to fly in the guys eye sitting down. Great test. Fail at SAFETY.
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*
So, next time maybe a bit more concrete shifted to top center? Is there a link to what the limitations are. What about specifics on concrete for this bram? Fiber? psi designed and tested? Mix ratios? Just curious
4:25 whoever put that board under the beam is a brave son of a gun...
It is notable that the amount of deflection just before the final failure would be clear and evidence that corrections and other safety strategies would give plenty of notice to implement an orderly plan take. Unless of course it occurred swiftly, like for example when my stepmother was the culprit
Why are we measuring in newtons all of a sudden instead of pounds or kilograms?
newton refers to force i believe ie the force needed to break the beam rather than weight
@@melin1969 Ok, but why the change? I guess I have to look up the equivalent now.
@@joewoodchuck3824 Metric units are used as Standard in Engineering/R&D.
Two things about you are rather loud:
1. American
2. Not an engineer
Not to worry though - you're in good company here I notice.
@@ddaytona1 Kilogram is metric.
IMHO I think the beam actually did break because of the "local pressure" point, not from the "general load"
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.
I'm sure OSHA would not approve sitting next to that device without some type of barrier.
Absolutely bizarre?
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?
hi im having my dissertation on flexural response of concrete beams reinforced with stainless steel bars at elevated temperatures...i need help!!
I and my colleagues did this back in 1973 at Eng School in Auckland, NZ
I did this in 8th grade.
@@edwardcornell1263 I did this before my first birthday.
What they should do is have them pull the cable, lay the cages, and pour the concrete for 16 hours a day for just a month. THAT'S a challenge.
Maybe they used to do it and decided that kind of work was too miserable.
So is this the job that the guys who watch paint dry get when promoted?
You can tell because they actually break out into rounds of applause when something happens.
these guys have induced all the force into two points ,try it again with the force applied evenly across the whole span.
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
2:01 First crack occurs with 8.3mm deflection - that's quite a lot! Concrete is surprisingly flexible, that it could absorb that much deflection without cracking. Also, it's interesting that the deflection seems to be linear with respect to the load until the first cracks appear, after which it starts to shoulder off. What does that say about what's going on inside the beam as it bends?
the steel is flexible
I read all the PPE complaints...Obviously, they do not understand PEE requirements...for example, steel toed shoes are not required unless a toe crush hazard exist.
You know your test and what hazards exist...they (complainers) need to relax...
Thanks for sharing your test; with that said, please, share what reinforcement was used and also the PSI of the concrete materials.
Thank you kindly, in advanced...
PS Would you have a detail of that in another video?
You can do what you want in Philly. But Ontario law requires them to wear glasses steel toes and hard hats. Not to mention the lack of barricades and warning signs. Labour board inspector shows up shuts the lab down and fines everyone involved.
So, you are telling me, in this school environment and NOT a workplace!... that your "labor laws apply"? That sounds like you do not understand this is in school and not a ''work area"... I will accept being wrong... but, please, send me the link that shows that... peace!
Philadelphia Construction Engineering it is a workplace. The instructor is being paid, it's his workplace. That and you'd sue this shit out of the school if your kid lost an eye or worse while this test was being done. As for the law , look up the Ontario occupational health and safety act. It's all there in black and white.
WHAT? The ''kids'' are adults! This is a university and this is not in the first year program (99%)... The instructor would have to report himself or someone like you would have to call on the school -- to make this complaint... The instructor could call on himself also - what?
Ultimately, the hazard has to be there... the instructor would clearly be able to show, that no eyes were lost in his ''hundreds'' of test-- therefore, the ''hazard'' is not present...
Of course, it is always more safe... the better... But, you snowflakes are getting all bent out of shape...
Philadelphia Construction Engineering there is all kinds of hazards in this test. 1 The beam had to be craned off a truck and installed on the test bed. 2 prestressed cables can and will shoot out of the beam if the tension is released rapidly.( 15 years of heavy concrete demolition experience. I've seen it happen.). 3 These people or going to be engineers crawling around construction sites they should be trained to wear the proper PPE. In Ontario glasses, boots, hardhat and highviz vests are the minimum requirements to enter any construction site. 4 if anybody on that site is killed or seriously injured during the test the supervisor is liable and will be tried and fined up to $100000. The employer ( the university) is liable and can be fined up to $250000 not including any civil penalties. The Labour board inspector can't be everywhere but if something happens the penalties can be severe.
really? no one have safety glasses or any type of protection for flying objects.
first thing I thought too, they must not have OSHA in Canadialand.
"What do you do for a living?"
"I sit at a computer wearing a hard hat and watch beams get crushed."
Lots of science, engineering, etc…going into this test, but where is the common sense? Computer guy is lounging a few feet away without any protective barrier, camera guy taking tourist photos isn’t far off, either. I’m shocked at how little went into the safety of these testers. Must’ve blown the budget on the earth-crushing hydraulic press!
How are the end supports connected to the press? What sort of structure is in the floor?
The beams are supported on triangular shaped structure which looks like a book end. The support structures must be bolted to the floor, which is made of embedded beams and concrete. Yes the floor is probably 10-12 feet thick of reinforced concrete.
I'm guessing Mr. Blue Helmet doesn't have to wear safety glasses while sitting next to a beam that is gonna explode in 1000 years?
that is all you can do is criticize video parts. arent you special
@@wildkatsailing He knew it won't explode, it just crumbles.
Fortunately, Chinese-made beams arrive pre-failed.
China is making half the constructions in the world and all them fail, yeah