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Originally posted by -PLB-
What happened to your "3rd law" "conservation of momentum" nonsense?
Originally posted by bottleslingguy
you asked what role the floors had in keeping the columns from falling and I said think of them as guy wires so you might be able to understand the design.
the floors sagged because when the concrete got hot it lost its tensile strength so it no longer contributed to holding its own weight and actually became part of the problem.
you really are a major intellectual stonewaller and I love how you change the subject or the point of a discussion when you don't want to go there. maybe if you could focus a little more on the really important aspects of the design and what effects the plane impacts had on those particular designs you may start to see light at the end of that 9 year tunnel.
Originally posted by ANOK
reply to post by wmd_2008
This is the problem you folks have, not enough knowledge about physics and construction to understand the different between partial and complete collapse.
The floors collapsing in that building didn't bring down the frame of the building with them did it?
There is more to the WTC collapse than just floors collapsing.
The problem with your argument is not so much that floors fell and continued to progressively collapse, because that can happen, the problem is that doesn't happen to steel framed buildings, and when it does happen you usually have either a partial collapse, or with concrete structures you end up with a stack of floors, like a stack of pancakes (another term who's meaning seems lost on you).
The WTC collapses do not show any sign of "pancake collapse". As noted by your NIST report.
NIST’s findings do not support the “pancake theory” of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system—that connected the core columns and the perimeter columns—consisted of a grid of steel “trusses” integrated with a concrete slab; see diagram). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.
www.nist.gov...
So why do you keep trying to insist it was a progressive pancake collapse when even the report you all claim to be experts about, and defend so religiously, does not support that?
You have no evidence for your claims because the "evidence" you use is nothing of the sort.
edit on 5/15/2013 by ANOK because: (no reason given)
Good work man, you finally did it!
Originally posted by -PLB-
...a desired force or motion! It was never desired for the entire mass of the two buildings to move 200 metres in less than 15 seconds each. If you argue the towers went mechanic, you have a lot of explaining to do. For example: were they designed as some sort of bear trap? As in: a relatively small input energy (plane crash, less than 5 GJ) was supposed to trigger a large energy output (more than 500 GJ)?
Originally posted by Akareyon
Good work man, you finally did it!
In all these years of debating you are the first to actually build a model of a tower that collapses progressively from top to bottom; the first to model the WTC 1&2 collapses!
And I really don't mean to poison this compliment by further discussing the implications, but I really consider this a breaking point. This thread should go down in the history of 9/11 conspiracy debates.
We both built a tower each. So what is the big difference, what are the similarities between your tower, my tower and the twin towers and what has been proven here? Apart from the obvious fact skyscrapers shouldn't be made of dishwasher tabs, of course :-)
The question was whether progressive collapse is inevitable in a steel-frame, tube-in-tube skyscraper, as many believe that this sort of stuff just happens due to slipshod architecture, whereas others argue that slipshod architecture leads to leaning, tipping, bending, breaking and tilting, but never to a progressive collapse from top to bottom.
-PLB-, your tower was not slipshod architecture. It surely was very shaky and fragile compared to mine - or the WTC.
In short, although I acknowledge your success in modelling a progressive collapse, my claim that the parameters for a tower that collapses the way yours and the WTC did are much narrower than for a tower that either dampens the impact or collapses asymmetrically has not been disproven.
My original objection was that a mechanism is... ...a desired force or motion! It was never desired for the entire mass of the two buildings to move 200 metres in less than 15 seconds each. If you argue the towers went mechanic, you have a lot of explaining to do. For example: were they designed as some sort of bear trap? As in: a relatively small input energy (plane crash, less than 5 GJ) was supposed to trigger a large energy output (more than 500 GJ)?
What are the chances that an architect would accidentally build a structure like your tower? What reason could an architect have to deliberatly build a structure like your tower? How many skyscrapers have - deliberatily or accidentally - been built the way your tower was built and threaten the lives of thousands every day? All of them, some of them, or just two of them? Why has there been no serios discussion about holding the architects accountable for designing a tower the way you have designed yours?
And lastly: would you want to live or work in a tower designed like yours, or would you prefer mine?
You have succeeded: you've proven my point instead of refuting it.
Originally posted by ANOK
reply to post by -PLB-
Not sure if you realise this, but your experiment proves nothing other than blocks piled on top of each will easily fall over and collapse, because they are separate components and not connected to each other.
You have not demonstrated a building collapsing, you have demonstrated that individual components, blocks, not connected together will fall over and drop to the floor if disturbed, and we already new that happens. You didn't need to drop anything on your model, you could have blown over if you blew on it.
Of course those small blocks will fall straight down there was nothing stopping them, no resistance from being bolted and welded together. They were not continuous for the height of the structure. The physics acting on your model does no represent the physics of a welded and bolted structure.
Nice try, but no soup for you. All you've done is proven once again you fail to understand the physics involved in structures.
Try gluing the blocks together along with the "floors", and see if you get the same result. I'll predict right now that you won't. In fact it would teach you something about resistance, which your model did not represent.
Resistance PLB, the ingredient for some reason you continually fail to address. You built a house of cards, and they do fall over.
And so did I. However, your building is more similar to the WTC than mine, at least when it comes to collapse. That makes me think about sleeping under clear blue skies and never enter a building anymore. If it doesn't worry you at all, that's fine :-)
Originally posted by -PLB-
This whole concept seems to be quite evident. I just looked at the WTC tower and created similar conditions.
So you say it was in the floors. I'd say it was more in the weight and dimensions of the blocks, I'll try thin paper then. What did you use, A6, A5? It's not clear really from the gif, and it's hard to interpolate from the size of your hand, the tabs and the wall tiles.
The big difference is that my floors were actually a lot weaker. Sure, it was strong enough to keep the blocks in place and carry itself, and if you had a miniature office you could place it there too. But when you drop large weights on it, it fails, just like how it happened in the WTC. Your floors on the other hand were much stronger than they needed to be.
That's why I said I would love to pick up your experiment. We should do what all good scientists do: exchange data, experiment, tweak the experiments, share experiences and analyse results. I checked my own dish washer tabs, they are a lot thicker than yours - my colums would be a little stronger.
You can not make these kind of assertion without doing a study first.
I know this discussion has been going on before in other threads, and this argument has been proven invalid, in my opinion. The towers weren't even built yet when another company issued a newspaper full-page ad of a plane crashing into one of them to advertise the dangers - and against their construction. One of the engineers is on record stating the towers could easily take multiple planes crashing into them, that a plane piercing the facade would be like sticking a pencil through a mosquito net. The Twins being hit by planes, being jumped on by King Kong or attacked or destroyed by something was a recurring idea in pop culture (comics, games, movies and so on) long before their demise. The towers were clearly designed with the Empire State building incident, a nearby airport, earth quakes, hurricanes and the cold war in mind and in a city with almost a century of experience in skyscraper building on the record. I'm sure noone was thinking: "hey, let's show them Russkies and build the tallest building of the world, but make it so cheap that all they have to do is send one spy and plant a bomb somewhere to bring it down".
The towers were never designed to stop the dynamic load of 15+ floors + columns + mast dropping on it. And why would they be? In what scenario other than a terrorist attack where suicide pilots fly planes into the building does this event occur? I can't really think of any.[...]It isn't that obvious to make a building save for an event that had never occurred and wasn't very likely to occur in the future. The whole discussion of suicide pilots flying into towers has only been started after 911.
Originally posted by Akareyon
So you say it was in the floors. I'd say it was more in the weight and dimensions of the blocks, I'll try thin paper then. What did you use, A6, A5? It's not clear really from the gif, and it's hard to interpolate from the size of your hand, the tabs and the wall tiles.
That's why I said I would love to pick up your experiment. We should do what all good scientists do: exchange data, experiment, tweak the experiments, share experiences and analyse results. I checked my own dish washer tabs, they are a lot thicker than yours - my colums would be a little stronger.
What's funny for example is that when I objected that orienting the Jenga blocks upright would make my tower too unstable and I would hardly make it to build a 6th floor, you suggested I use thicker paper or envelopes. Now we know using extremely lightweight columns and the thinnest possible paper seems to do the trick. Why is that? Because less energy is needed to bend the paper, which in turn pulls on the "hinges" of the colums, levering and dislocating the tablets from their position, which in turn cancels the friction that keeps the next paper floor in place. In a sense, the solid structure turns "liquid", as the towers did. Technically, the sum of all latent forces pointing downwards was greater than the sum of all forces pointing upwards, something any engineer will try to avoid at all costs.
I know this discussion has been going on before in other threads, and this argument has been proven invalid, in my opinion. The towers weren't even built yet when another company issued a newspaper full-page ad of a plane crashing into one of them to advertise the dangers - and against their construction. One of the engineers is on record stating the towers could easily take multiple planes crashing into them, that a plane piercing the facade would be like sticking a pencil through a mosquito net. The Twins being hit by planes, being jumped on by King Kong or attacked or destroyed by something was a recurring idea in pop culture (comics, games, movies and so on) long before their demise. The towers were clearly designed with the Empire State building incident, a nearby airport, earth quakes, hurricanes and the cold war in mind and in a city with almost a century of experience in skyscraper building on the record. I'm sure noone was thinking: "hey, let's show them Russkies and build the tallest building of the world, but make it so cheap that all they have to do is send one spy and plant a bomb somewhere to bring it down".
Originally posted by -PLB-
So to mimic truss seat failure (which is the main resistance in the WTC), in our model the paper needs to bend, and start pulling itself from underneath the blocks and overcome the friction (which is the main resistance in the WTC).