For the dumb of us: Why could the building not tip over?

[Undesired Walrus]

I've searched in vain on this site, but all I can find is links to Bazan/Bazen/Baz Lurman with horrific looking calculations I have no idea about.

So here, I am offering myself, to truthers and skeptics, to tell me why the building could/could not tip over.

[T.A.M.]

Take a uniform steel bar and hold it so it length wise up and down. Now drop it...it falls to the earth like a spear, straight down.

Now tilt it by 15 degrees from the up and down axis, and see if it tips, or goes back to straight and falls, once again like a spear.

Now see how far you have to tilt it away from the vertical axis in order to get it to fall so it lands on its side so to speak.

That is why

TAM

[Undesired Walrus]

Originally Posted by T.A.M.

Take a uniform steel bar and hold it so it length wise up and down. Now drop it...it falls to the earth like a spear, straight down.

Now tilt it by 15 degrees from the up and down axis, and see if it tips, or goes back to straight and falls, once again like a spear.

Now see how far you have to tilt it away from the vertical axis in order to get it to fall so it lands on its side so to speak.

That is why

TAM

Ah, but is not the classic truther conclusion that

a) If you dropped that steel bar onto a load of other vertical steel bars, it would hit them and tilt off

b) Some Stephen Jones stuff

Hey, I'm just asking questions.

[tkingdoll]

Originally Posted by Undesired Walrus

Ah, but is not the classic truther conclusion that

a) If you dropped that steel bar onto a load of other vertical steel bars, it would hit them and tilt off

Hrm, this doesn't follow, because doesn't the steel bar represent the entire building?

So the comparison would have to be 'a steel bar composed of tens of thousands of little steel bars, concrete, glass etc'. Which would still fall in the manner described.

[R.Mackey]

Remember that the buildings were over 200 feet across.

To tip over, it has to crunch the structure below, and only on one side, through a volume of literally hundreds of thousands of cubic feet. All the while, the upper portion and the "hinge" supporting it have to hardly crunch at all.

Doesn't happen. If only a small portion of the lower structure is supporting the upper structure, it gives way. You cannot support a hinge for very long.

This is why the upper blocks both rotated a few degrees, but not enough to actually topple over.

A more detailed analysis requires quite a few assumptions, all of which are up for debate, but suffice to say that nobody has yet produced a model that predicts anything close to toppling. Eager young Truthers, step right up and be the first.

[Undesired Walrus]

Is the only thing left for Dylan and co the 'Tip over' conclusion?

[beachnut]

Originally Posted by Undesired Walrus

I've searched in vain on this site, but all I can find is links to Bazan/Bazen/Baz Lurman with horrific looking calculations I have no idea about.

So here, I am offering myself, to truthers and skeptics, to tell me why the building could/could not tip over.

go get a metal tape measure

slide it out straight up, tilt it, oops it fell down

this beats the summation of that big expression from 0 to H1 were (m/H1) with theta or double dot theta cos theta xdx = 1/2 H1m theta(double dot) cos theda, the double dot means something, i forgot; = 3/8mg sin 2 thedas ; run it is going to get messy on the chalk board

that is why using a tape measure is better

[T.A.M.]

UW:

Yes, but since we know the floors below offered a miniscule amount of resistance, would they have contributed in any substantial way to tipping the building? Not likely.

Perhaps, I would say then, take said metal bar, drop it through soap bubbles, and see what happens...lol

TAM

[MG1962]

An easy way to see what happened. Get a glass of water and a bucket of water. Throw the water out of each. You will notice the water in the glass goes further.

What you have are two competing forces. Your effort to throw the water, and gravity. The heavier something is, the more sideways energy is needed, and the more effect gravity has

In the case of the towers, the tops did indeed try to topple towards the section of the first failure. Because of the sheer weight of the upper segment, the need to drop was more compelling that the need to go sideways

[T.A.M.]

Originally Posted by MG1962

An easy way to see what happened. Get a glass of water and a bucket of water. Throw the water out of each. You will notice the water in the glass goes further.

What you have are two competing forces. Your effort to throw the water, and gravity. The heavier something is, the more sideways energy is needed, and the more effect gravity has

In the case of the towers, the tops did indeed try to topple towards the section of the first failure. Because of the sheer weight of the upper segment, the need to drop was more compelling that the need to go sideways

exactly, but said much better than my example...lol

TAM

[GT/CS]

Remember, the block you need to analyze is from the floor of collapse upward, not the entire building. There is no way for such a block to tip over. If the planes had hit the bottom floors the towers might have tipped over.

[GlennB]

I would have said - because it's not a unit structure like a tree. Each building was composed of many thousands of elements joined together and designed to create stability against certain - known - vertical/horizontal stresses.
Tipping wasn't one of them.

[Anti-sophist]

In order for the building to tip, the "hinge" point would need to be able to support the entire building. Furthermore, the horizontal support would need to be able to transmit forces to the opposite side (from the hinge to the tipping side). These were -not- designed for this type of force, at all.

One of the two towers does start to tip (see cover photo at debunking911) until the "hinge" section can no longer support the weight of the entire section and begins to come apart.

[GlennB]

Originally Posted by MG1962

...

In the case of the towers, the tops did indeed try to topple towards the section of the first failure. Because of the sheer weight of the upper segment, the need to drop was more compelling that the need to go sideways

Dunno if I'd put it quite the same way

A ball shooting off the side of a table has a fixed horizontal speed (assuming in a vacuum).
However, it will accelerate downwards.

[Undesired Walrus]

I'm asking partly out of interest because the idiot is emailing me again. Although, no longer going on about the tip over.

His recent entry is that a 707 has a fuel capacity of 23,000 gallons and a 757's is 11,500 gallons.

Is there not something seriously wrong here?

[boloboffin]

An great thought experiment I've heard is imagining one of the twin towers raised a mile off the ground by Lex Luthor (stay with me). Superman comes barreling along just as Lex drops the tower. Can Superman catch the tower and prevent its destruction?

Perhaps, but not by flying up and grabbing hold at a single point. The buildings aren't designed to have all of their weight supported at any single point. If Supes grabs a core column, the building would tear loose of the supported column in an instant. If Supes grabs the antenna, the building would again tear loose because the upper floors are not designed to support the weight of the lower floors.

The error in thinking that these buildings would tip is considering them a monolithic unit. In reality, they are enormous structures to redistribute loads. They would never be able to be completely supported by any possible pivot point long enough to tip over. There will only ever be a crush-up or a crush-down when we are talking about structures of this size.

One good place to see this is the core column spires left by the collapses. You can see them start to tilt (lateral force provided a momentary pivot point down below), and then they fall straight down. They crush up, because even that lesser amount of weight is enough to overwhelm the structure.

Any picture of a tipped over building I've ever seen is less than eight stories. They just don't fall that way when they get the size of 1, 2, and 7.

[R.Mackey]

Originally Posted by Undesired Walrus

I'm asking partly out of interest because the idiot is emailing me again. Although, no longer going on about the tip over.

His recent entry is that a 707 has a fuel capacity of 23,000 gallons and a 757's is 11,500 gallons.

Is there not something seriously wrong here?

Not "wrong," more like "inaccurate" and "irrelevant."

The Boeing 707 had anywhere from about 12,000 to 24,000 gallons capacity depending on variant (Boeing 707 story).

Same for the 767. A 767ER also holds about 24,000 gallons.

Also remember that the 707 was much older and had four engines, whereas the 767 has two. The 767 is more efficient fuel-wise.

ETA: Oops, you said "757." Well, that plane is not directly comparable. It's designed for short- to medium-range only, so there is no ER variant, and unsurprisingly, it matches the short-to-medium range 707 variants with respect to fuel load.

I assumed you were comparing to a 767 because that's what hit the World Trade Center, not a 757. I have no idea why a 707 would be at all relevant to the Pentagon or to Shanksville.

[T.A.M.]

Originally Posted by Undesired Walrus

Is there not something seriously wrong here?

yes, the fact that you are letting him continue to email you...

TAM

[Quad4_72]

From what I understand the towers were not solid objects and were composed of millions of pieces held together by welds, nuts, and bolts. I could be wrong on that though...cause Dylan suggests that the towers were supposed to act as solid objects.

[leftysergeant]

As long as the core columns are not compromised below the zone of collapse, there is nothing going on that COULD tip the buildings over. They were designed to resist lateral forces. But, very structure has its breaking point.

Any structure will, eventually break where force is applied or transmitted. The force of the falling floor and perhaps of the hat truss would have hammered the core horribly, breaking joints, but only at the top..

The only force to which the lower portions of the building were subjected were those they were intended to resist, until the gathering mass above them had some magnified itself that the lower elements began to fail as well. By this time, the center of gravity was well toward the bottom of the towers, less high than the buildings were wide. In this case, they colud not tip over, but, instead, spread out when the zone of collapse arrived, pushing the facade, still standing up right, into other surrounding builldings.

Even after the core had begun to fail as far down as it was to be seen in the pictures of the spires, just the force of the falling concrete and steel would have been pressing in from all sides against the spire to keep it more-or-less vertical.

Does that make more sense to the engineers than all that geek talk make to me?

[MG1962]

Actually as a thought exercise - What do people think may have happened if the base of the building had suffered the same level of destruction. Would the Towers have attempted to topple before disintergrating, or simply come down pretty much the way they did?

[boloboffin]

Originally Posted by MG1962

Actually as a thought exercise - What do people think may have happened if the base of the building had suffered the same level of destruction. Would the Towers have attempted to topple before disintergrating, or simply come down pretty much the way they did?

I think we would have seen a little bit of leaning as collapse initiated, but with the full weight of the towers to deal with, the buildings would have crushed up much earlier in the process. If anything, we might have seen the remarkable sight of the towers travelling upright in one direction as they crushed up, until they hit an adjacent building, and then all bets would be off. But that would require some serious lateral force at the beginning, and I don't think that much would build up before the crush up began.

I could see the antenna on top of the North Tower finding a pivot point and tipping over. But that could be wrong as well. We've never seen buildings that large fall down before, until 9/11.

ETA: I have heard that with damage much lower than the South Tower's, the buildings may have collapsed instantly.

[einsteen]

Originally Posted by MG1962

Actually as a thought exercise - What do people think may have happened if the base of the building had suffered the same level of destruction. Would the Towers have attempted to topple before disintergrating, or simply come down pretty much the way they did?

That's an intelligent question MG1692. The offical theory says it would lead tot a total crush-up, that means it is indistinguishable from a normal controlled demolition. In Bazant's paper that is the crush-up calculation and for Greening the 2nd stage of collapse, note that this is only a special case of the crush-down crush-up calculation, nothing more.

I doubt the strength of the building would lead to a total collapse in this way, because if you look at the landmark they don't implode it completely from the bottom, that would probably lead to toppling or a half implosion and big chunks that topple (of course afterwards with the centre of mass still at the centre of gravity).

One thing is sure, if you can prove that the wtc would not collapse if you remove the bottom story you also prove that the collapse we have seen is not gravity driven.

[Gravy]

Einsteen, did you know that skyscrapers aren't designed to be picked up and dropped? It's true!

[GlennB]

Originally Posted by MG1962

Actually as a thought exercise - What do people think may have happened if the base of the building had suffered the same level of destruction. Would the Towers have attempted to topple before disintergrating, or simply come down pretty much the way they did?

Intuitively, I'd imagine they would collapse rather more like those old brick chimney stacks that Fred Dibnah used to demolish, but with less lateral spread relative to the height. Just a wild guess, though.

[Architect]

Originally Posted by GlennB

I would have said - because it's not a unit structure like a tree. Each building was composed of many thousands of elements joined together and designed to create stability against certain - known - vertical/horizontal stresses.
Tipping wasn't one of them.

Bingo.

I'll get my secretary to raise an invoice for my time.

[mjd1982]

Not an engineer, but maybe in the light of the explanations given here, someone can explain this collapse

http://www.youtube.com/watch?v=-1X8j53U1So

[DGM]

Originally Posted by mjd1982

Not an engineer, but maybe in the light of the explanations given here, someone can explain this collapse

http://www.youtube.com/watch?v=-1X8j53U1So

This masonry building has what to do with 9/11?

[DGM]

Quote:

Originally Posted by MG1962
Actually as a thought exercise - What do people think may have happened if the base of the building had suffered the same level of destruction. Would the Towers have attempted to topple before disintergrating, or simply come down pretty much the way they did?

No. the remaining collumns would have to bear the whole load and would fail causing the same type of collapse. Gravity/load distibutions funny like that.

[GlennB]

Originally Posted by mjd1982

Not an engineer, but maybe in the light of the explanations given here, someone can explain this collapse

http://www.youtube.com/watch?v=-1X8j53U1So

I would depend on the size/construction of the building and the cause of the collapse.

Can you enlighten us?

[BeAChooser]

I can't resist. This just belongs on this thread:

http://www.youtube.com/watch?v=UMtb5Vndo2g&NR=1

ROTFLOL!

[R.Mackey]

Originally Posted by mjd1982

Not an engineer, but maybe in the light of the explanations given here, someone can explain this collapse

http://www.youtube.com/watch?v=-1X8j53U1So

You mean "why did this building tip over, when the WTC Towers didn't?" Easy. That building is only ten stories high (roughly) and looks to be under 30 meters across. It also appears to be made of concrete and should have lower demand-to-capacity ratios of the "hinge" members.

As a building gets taller, its ability to support rotational moment decreases approximately as the square of its height, thanks to the increase in moment of inertia. And this assumes the taller building is beefed up accordingly. If the shorter building is overbuilt, then the taller building may be even less able to topple intact due to reduced elastic buckling strain. The WTC Towers, being 110 stories, would be at least 100 times less able to topple in this fashion by geometry alone.

This is why very tall structures, even those of high strength-to-weight and those where a good "hinge" is guaranteed like radio towers, rarely topple intact without buckling in the middle.

Basic structural mechanics. This is why "argument by analogy" is total crap. This is also why the Truth Movement uses it so often.

[strathmeyer]

I think a more apt analogy would be a house of cards. Or a skyscraper of cards.

[chippy]

Yeah well, can someone explain to me how THIS building collapsed!?!?!?!?

http://www.youtube.com/watch?v=MKD6o3nsKkM

It gets touched by a microphone cord and collapses? Yeah right! Is the american public completely inept? Who's gonna believe that!?

By the way, Undesired Walrus, you should be grateful for the fact that your buddy LUCUS has a huge mouth and just can't help but brag about you actually being an LCF member and that you're just trying to cause disarray here. Good old LUCUS.

[WilliamSeger]

Originally Posted by Anti-sophist

In order for the building to tip, the "hinge" point would need to be able to support the entire building. Furthermore, the horizontal support would need to be able to transmit forces to the opposite side (from the hinge to the tipping side). These were -not- designed for this type of force, at all.

One of the two towers does start to tip (see cover photo at debunking911) until the "hinge" section can no longer support the weight of the entire section and begins to come apart.

In addition to supporting the weight, the "hinge" point would also need to resist an "equal but opposite reaction" of the top mass moving laterally. As it started to tilt, the top block would be trying to rotate around its center of mass, pushing the remaining columns in the direction opposite the tilt, which would considerably reduce their ability to resist the downward forces.

[Drudgewire]

Originally Posted by BeAChooser

I can't resist. This just belongs on this thread:

http://www.youtube.com/watch?v=UMtb5Vndo2g&NR=1

ROTFLOL!

[LashL]

Originally Posted by R.Mackey

You mean "why did this building tip over, when the WTC Towers didn't?" Easy. That building is only ten stories high (roughly) and looks to be under 30 meters across. It also appears to be made of concrete and should have lower demand-to-capacity ratios of the "hinge" members.

As a building gets taller, its ability to support rotational moment decreases approximately as the square of its height, thanks to the increase in moment of inertia. And this assumes the taller building is beefed up accordingly. If the shorter building is overbuilt, then the taller building may be even less able to topple intact due to reduced elastic buckling strain. The WTC Towers, being 110 stories, would be at least 100 times less able to topple in this fashion by geometry alone.

This is why very tall structures, even those of high strength-to-weight and those where a good "hinge" is guaranteed like radio towers, rarely topple intact without buckling in the middle.

Basic structural mechanics. This is why "argument by analogy" is total crap. This is also why the Truth Movement uses it so often.

There you go again, posting facts and reality based upon real life expertise.

This is why most "truthers" run and hide from your posts; your posts are to "truthers" as garlic and silver stakes are to vampires*.






(*I do not believe in vampires or the talismen associated with them, but since most "truthers" believe in all manner of woo, I invoked a bit of licence.)

[gumboot]

Originally Posted by Undesired Walrus

I've searched in vain on this site, but all I can find is links to Bazan/Bazen/Baz Lurman with horrific looking calculations I have no idea about.

So here, I am offering myself, to truthers and skeptics, to tell me why the building could/could not tip over.

In simple English, the building can only tip over if the centre of mass moves outside the building's footprint. This requires an enormous amount of lateral force which simply didn't exist.

The force was all directed downwards, because the only force contributing to the collapse was gravity.

-Gumboot

[Undesired Walrus]

Originally Posted by chippy

Yeah well, can someone explain to me how THIS building collapsed!?!?!?!?

http://www.youtube.com/watch?v=MKD6o3nsKkM

It gets touched by a microphone cord and collapses? Yeah right! Is the american public completely inept? Who's gonna believe that!?

By the way, Undesired Walrus, you should be grateful for the fact that your buddy LUCUS has a huge mouth and just can't help but brag about you actually being an LCF member and that you're just trying to cause disarray here. Good old LUCUS.

What?? Why did you send me that PM too?

[leftysergeant]

Actually, the towers were sort of like trees. They were rooted strongly in the substrate in the basements.

Do all the violence you want to the top of a tree, and see if it topples.

Do it to the trunk more than half way down, you might have to run.