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 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 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.
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
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?
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.
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.
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?
@@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.
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.
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.
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.
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).
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
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
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.
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.
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?
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?
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
How green was this concrete. Age/days? Wouldn't you want a few test beams at 7 day intervals from the date of pour to test the failure curve? Just asking.
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.
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.
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?
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.
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.
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.
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.
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
This depends partly on what kind of ton. What I consider a ton is a "short ton" or 2000 pounds. 1 kn is about a tenth of a ton (1/8.896) and 156 kn is 17.5 ton-force (the gravitational force on a 2000# ton of mass at sea level)
4:05 Load is kept constant, yet the deflection increases. This is definition of ductile failure. In this case, failure of the beam should not be confused with the violent behaviour at 4:58. This is correct?
that's not the beam failure... it's just yielding. deformation increases without adding more load when it happens. the beam, actually, failed when the concrete was crushed. when the concrete fails, we see this violent behaviour.
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.
Testing a beam at a single point wouldn't tell you anything worth knowing. You would only be applying stress in one concentrated spot, whereas the stress concentration of a four point test is over a larger region, avoiding premature failure.
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.
Everyone in the comments apparently works for osha..
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...
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 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?
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!
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 💭
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?
Quite literally the slowest - yet most entertaining video I've seen this year.
Why no personal protection equipment?
They had helmet.
aha, no safety screens
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.
Wow, as strong as 163 Fig Newtons! Man, that's a lot!
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.
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.
is the monitor randomly moving the image to prevent burn-in?
yes exactly
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 ☺️
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.
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
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.
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.
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?
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.
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.
Thought that paint would never dry!
😑yep
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”
hi im having my dissertation on flexural response of concrete beams reinforced with stainless steel bars at elevated temperatures...i need help!!
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.
It's good to see critical, load bearing construction materials being subjected to such testing.
Lives depend on the quality of these beams.
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
engineer: i think i can improve this beam a bit..
beam: haha... that cracks me up..
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 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.
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.
What is the capacity of the machine?
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
what's up with the computer screen image floating around when the video speeds up? some built in image burn prevention?
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...
did that beam buckle at failure or was it the prestressed / destabilising load that cause that horizontal movement
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.
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).
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
what machine used for this test ?
wow no safety shields on utm 🥵
Don't need safety shields for concrete, the moment the material gives.. The pressure is gone.
were they testing for unconfined buckling at the top?
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
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
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 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.
2:20 why is image on monitor shifting left and right?.......
To prevent burn-in, it likely displays the same image all the time so they cycle the pixels to keep them working
@@pmolz will the burn-in occur even if the screen is LED?
@@akhilmt9731 With normal use, no, but they may suffer from temporary image retention which goes away after awhile
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?
in real life their is alot of vibration on beams dose your test account for this or is it strictly load
the suspense is killing me
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 🤣
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
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
Surprised to see the lack of care precautions for the risks to people around in a destructive load test like this!
It's safe...
How green was this concrete. Age/days?
Wouldn't you want a few test beams at 7 day intervals from the date of pour to test the failure curve? Just asking.
they tested it on the 28th day.
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.
That was neat seeing the way it flew apart at the top when it finally reached compression failure... Thanks for sharing.
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.
That's a solid win for them. Great job guys!
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
What measuring scale is the “KN”?
KiloNewtons=weight
@@Iceman2367 Newton is a unit of force
Wow
Engineers. Metric system is better for this. The imperial equivalent is pounds-force, and everyone hates working with pounds-force
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.
Cool, during the fast forward bit you can see the burn-in protection on the TV slowly shifting the display.
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.
No eye protection?
High tech ,fully equipped, state of the art , crack analysis right there.
does a reverse arch do much? seems pointless other than adding mid span mass.
i need scientific data on that.
absolutely, truss joists on most shopping centers are guilt the same way. The bearing point on girders is minimal. Go into ,Home Depot and look up.
That's why It is ideal that the design of beam is tension controlled
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?
Quick, Bob, put some spackle on that before the inspector shows up...
What does ‘harped’ mean?
The fashion in which the rebar embedded inside the beam is arranged to resist the bending moment.
Say no to crack.
LEFM is a magical thing. When this video started I already knew where the cracks would form
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?
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.
Safety thinking = alien concept
what is the Test Method Standard did you use for this test? third-point loading?
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.
Tou ahould mention beam specifications by the way
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.
CoreSlab is nearby. Please put PSI/SAE values in as well as n/m
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.
how can adjust the setting of flexural test on UTM ibertest machine.kindly send me the information.
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.
why does the computer screen seem to wiggle in fast forward mode?
Prevents burn in on the screen.
Good thing it was recorded in slow mo..... the video finished just as I woke up. Good timing.
its kindof weird load putting on it. two small spots. instead of doing it over a larger area
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
How many pounds or tons is 156kn? Thanks
This depends partly on what kind of ton. What I consider a ton is a "short ton" or 2000 pounds. 1 kn is about a tenth of a ton (1/8.896) and 156 kn is 17.5 ton-force (the gravitational force on a 2000# ton of mass at sea level)
156kN ~ 35000 pounds
Duud: arrive in the metric system. Even better in the SI.
Welcome to the hydraulic press channel, and here we go,
holy shiit!
4:05 Load is kept constant, yet the deflection increases. This is definition of ductile failure. In this case, failure of the beam should not be confused with the violent behaviour at 4:58. This is correct?
that's not the beam failure... it's just yielding. deformation increases without adding more load when it happens. the beam, actually, failed when the concrete was crushed. when the concrete fails, we see this violent behaviour.
@@JorgeOliveira-ww8ry Yielding is a form of failure, beams designed under a stress code are not allowed to surpass the yield point.
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?
why apply the load via two pads?
How often does that happen in real life?
***** Yes, But is that what happens in real life situations such as bridges or roof beams?
Why not apply one single load pad?
Testing a beam at a single point wouldn't tell you anything worth knowing. You would only be applying stress in one concentrated spot, whereas the stress concentration of a four point test is over a larger region, avoiding premature failure.
Electron That presupposes all loads is over a wide area and not a single point.
Rose White I don't think you understand how beams work or what they are designed for.
I understand perfectly.
Beams is beams and many have a single point loading if you could understand things.
When Beam fails, switch to a nice single malt
Aluminum?
No its concrete
Sand
Volcanic ash on steroids