The science of why it had to be controlled demolition, in laymen's terms

I remember thinking 'How are they going to deal with that?' when I watched the attack live on TV. Leaving the towers in that condition would have been extremely dangerous and crippled a large part of the city for a long time.

Destroying them on the same day was a win/win for the people behind it. 9-11 was a short operation with maximum damage and minimal cleanup.


en.wikipedia.org...

American Airlines Flight 11 (a 767-200ER) and United Airlines Flight 175 (a 767-200) into the towers. 1 WTC was hit at 8:46 a.m. by Flight 11 between the 99th and 93rd floors. 2 WTC was hit at 9:03 a.m. by Flight 175 between the 85th and 77th floor.

The south tower (2 WTC) collapsed at 9:59 a.m., less than an hour after being hit, and the north tower (1 WTC) followed at 10:28 a.m.

The "Shock & Awe" of the attacks took place in the length of a feature film or sporting event. Why? Attention span and effect.

WTC 1: 8:46 am - 10:28 am : 1 Hour 42 Minutes
WTC 2: 9:03 am - 9:59 am : 0 Hours 56 Minutes

The support structures of the buildings were being cut and weakened during and possibly before any plane struck the building. The buildings did collapse under their own weight from the weakening of the internal structure but it was aided through pyrotechnic assistance.

The beams and main structural components were sliced through with thermite rope or something similar. That could have easily been triggered with a phone call to a land line or some other simple means. A timer even.

The pulverizing of the concrete is easily done by rigging something like a land mine (a device that will trigger when tampered with appropriately) to the collums. When the building is falling it will trip the explosive and cause an appropriate sized explosion. These explosives are not using shrapnel to do damage but a blast wave of energy. The smothering of the explosion with the upper floors causes pulverization of the concrete and building material. The building turns to dust as the energy from the blast is absorbed.

I think the use of the words 'explosives' and 'explosion' bring the wrong type of mental images to people's minds. Think blast wave energy designed to be absorbed by matter (which will tear it apart) and not shrapnel pieces being flung out to perforate a target.

Originally posted by Spoodily

I think the use of the words 'explosives' and 'explosion' bring the wrong type of mental images to people's minds. Think blast wave energy designed to be absorbed by matter (which will tear it apart) and not shrapnel pieces being flung out to perforate a target.

I will not disagree it can lead to confusion for people completely unfamiliar with the use of demolitions. Unfortunately, the word explosives has to be used for describing implosion effect, because gunpowder explosives are normally used for both external outward explosion and internally planting explosives to cut (not explode) the metal beams at a 45 degree angle.

I would guess the use of the the word explosion is what normally puts most laypersons in mind of outward explosion, without a thought given to the science of implosion effect using explosives.

Prior to 9/11, practically everything most people viewed, including the special effects scenes in movies, show explosives almost exclusively used for blowing outward, not creating a vacuum effect to pull them inward.

Originally posted by jthomas

Originally posted by ZeuZZ


As we know from watching the videos of the collapse of WTC2, global collapse began before the tilting of the top section reached a sufficient angle for the center of gravity to go beyond the edge of the building.

So what exaclty was causing this 'global collapse' when the top section was completely outside the original structure?

As I explained, the top section never got outside the structure. The acceleration of gravity of the falling structure quickly exceeded the motion of the tilting of the top section.

The top of the South Tower was definely shifting to lean to the outside of all lower floors. Thus, the rift that occur on three walls left only one wall to support the top floors with help from the portion of the center core that had not been cut.

At 9:37 am, the the top floors of the South Tower rifted and shifted outward at approximately 23 degrees. It wasn't until 9:59 am, the South Tower came straight down in less than 10 seconds. The leaning top floors were still attached and still leaning. The only reason three buildings fell as swiftly as they did is they had no support resistance. The beam support resistance had been strategically, successfully cut on three WTC buildings.

Without correctly strategically cutting the support beams, it would have taken many, many minutes not 10 seconds or less for any of the three buildings to fall outside their own footprints. Instead, there would have been toppling floor upon floor and would not have necessarily taken down all four walls on any of the buildings. The guaranteed portions still standing as they had been would have been the core supports. The building around those supports would have peeled away for those portions peeling away from the core.

Originally posted by ZeuZZ
As I explained, the top section never got outside the structure. The acceleration of gravity of the falling structure quickly exceeded the motion of the tilting of the top section.

I'm not sure how you know that, unless you have xray eyes, and can see through the immense dust cloud that was created.
The last it was seen at was at 23 degrees, toppling over.

Here you are conflating the line between what should have happened, with what did happen. Its all very well stating what did happen, but what should have happened is completely different, it should still be standing.

No, because the top section caused the global collapse.

Again that is what did happen, what should have happened is quite a different story, which i hope I illustrated clearly in the previous diagrams.

Not at all. It did it one floor at a time.

All of the columns were made of continous metal, from top to bottom, so the space bewtween floors is holding up just as much as the actual floors themselves.

Simple computations shows that the kinetic energy of that mass falling the 8 or so feet

WHOA, hold on a minute, you are saying that the top section fell eight feet? how does it start to fall eight feet when ALL of the supports were continous throughout the entire building? It was not just the floors providing resistance, every single millimetre of the building should be providing resistance as it falls. It looks as if you are modelling the building with nothing but empty space between each floor. It shouldn't have started to collapse, the core under the damage would still be providing resistance.

first on the most damaged side, then under the whole top section, far exceeded the ability of each storey to withstand that force.

Again, the whole building should have been slowing it down, not just the floors. The soace between floors was just as strong.

Remember also that during construction, the core columns could only stand on their own about a dozen floors. The design required that the core columns be tied to the outer walls via the floor trusses in order for the building to be constructed at all

That still does not account for how the struture below the damage stopped providing any resistance to the structure on top, it was not damaged.

I already gave you many but you dismissed them without addressing them.

Did you read my post? I responded to the first five, its just that i couldn't find any real information about the science of the collapses. If you could find it, as that was what the OP was about, that would be great post it here, because i couldn't. like this one for example; www.journalof911studies.com...


[edit on 13-12-2007 by ZeuZZ]

Originally posted by sheetrockerr

Next, we have David Griffin's content:

1. He is correct about the sudden heating of steel and the melting/sagging, but we are not talking the steel melting. We are talking about the affect of heat and how in contributed to the loss of strength it had and Malleability.

Yes we are talking about malleability, and as far as i've checked, metals heat up at a constant rate, not suddenly breaking like the twin towers did. They should have started bending and sagging gradually, but the collapse onset is near free fall speed. And you can calculate that, each floor is approx 9 metres.

When the support was lost, it did drop down, but the section was at an angle, not sliding down the core, thereby damaging the core on it's descent.
3. In the case of the WTC collapsing, the force was increasing exponentially, which each floor was not designed to support.

The actual speed of the initial collaspe refutes that as it clearly started quickly, near freefall speed. If it was exponential that would mean it would start gradually. You are correct, it should be roughly exponential, but it clearly was not, take a look;

5. The dust clouds were a cumulative affect of the many different materials.

Theres no way that all those clouds could have been created at that early stage of the collapse, concrete when put under pressure does not turn into puffs of smoke and dust, it shatters. Fireproofing does not turn into dust, the main source for dust would be the concrete. Theres not enough energy input to create that amount of dust that early because the only energy available to the official account is the gravitational energy. It actually takes quite a considerable amount of energy to create that amount of dust.


[edit on 13-12-2007 by ZeuZZ]

Originally posted by jthomas

There is no evidence that the bottom rapidly dropped "faster than gravity would allow without controlled demolitions." Many have made that claim but have not backed it up with any evidence. In fact, I haven't see anyone state what constitutes "faster than what gravity would allow" without being able to model the collapse itself, something we know is computationally far too difficult even with today's super computers.

Both WTC 1 and 2 collapsed in less than 10 seconds. WTC 7 collapsed in 6.5 seconds. That definitely indicates bare minimum resistance to free fall. It also indicates a vacuum effect has been created. That could only have been artificially done with controlled demolitions. All that flow being expelled is another indicator a vacuum has be artificially created by lack of center supports and vacuum expelling resistance (pulverized debris and air).

WTC 1, 2, and 7 literally fell into themselves to land in their own footprints. If you view the controlled demolition effect on WTC 7, the center roof of the building is the first sign of collapse and then the entire building fell into itself in it's own footprint. Only controlled demolitions, creating a vacuum due to cutting the center support core beam resistance, could have made that happen.

Had the buildings not had controlled demolitions used, it would have taken many minutes, not under 10 or 7 seconds, for even one side of any of the buildings to peel from the center core, with the top floors finally reaching the ground outside any building's own footprint. The effect would be kaboom (pause) for every floor on any side actually drastically compromised from the center core out. Why? Because of momentum resistance from all floors not having been intentionally compromised.

The dropping of any building, by controlled demolitions, removes almost all resistance from lack of center support. Vacuum effect expels any other resistance from the increasing mass and weight falling from above. There is no guarantee all floors, or at least supporting trusses, would have peeled from the core beams due to trusses being compromised at high levels under conditions the "official" version states.

What I have related above is proven physics facts. Free fall occurs faster without resistance slowing momentum.

I am not trying to insult anyone by asking the following question. Exactly what do people arguing against controlled demolitions understand regarding free fall with resistance (natural outside conditions) vs. no resistance (unnatural conditions in a vacuum)? There is definitely a difference in time from start to finish free fall outside vs. inside a vacuum.

All objects free fall at the same rate in a vacuum where weight and mass do not matter as stated to us by Galileo. That is not the case of free fall outside a vacuum unless one is internally naturally or unnaturally created.

Originally posted by OrionStars

The top of the South Tower was definely shifting to lean to the outside of all lower floors. Thus, the rift that occur on three walls left only one wall to support the top floors with help from the portion of the center core that had not been cut.

At 9:37 am, the the top floors of the South Tower rifted and shifted outward at approximately 23 degrees. It wasn't until 9:59 am, the South Tower came straight down in less than 10 seconds. The leaning top floors were still attached and still leaning. The only reason three buildings fell as swiftly as they did is they had no support resistance. The beam support resistance had been strategically, successfully cut on three WTC buildings.

As I explained carefully, the center of gravity of the top section never exceeded the edge of the building before collapse initiation. Also, although there were signs of very slow tilting long before the collapse, the collapse did not begin until the failure occurred seconds before collapse intiation as seen in all the videos.

See, for instance, youtube.com...

As I also demonstrated, WTC 2 collapsed in about 14 seconds, not 10 seconds as you state. See youtube.com...

Clearly, your speculation does not mesh with the known facts and observations.

Originally posted by OrionStars

Both WTC 1 and 2 collapsed in less than 10 seconds. WTC 7 collapsed in 6.5 seconds.

All your times are incorrect. Again, you can easily see WTC 2 fell in around 14 seconds from this video I already posted:

youtube.com...

Also, WTC 7 took over 13 seconds to collapse from beginning to end, also as seen in this video:

youtube.com...

Note that you cannot exclude the penthouse collapses.

So, you can see that the times you quoted are in error.

Originally posted by jthomas
All your times are incorrect. Again, you can easily see WTC 2 fell in around 14 seconds from this video I already posted:

youtube.com...

Also, WTC 7 took over 13 seconds to collapse from beginning to end, also as seen in this video:

youtube.com...

Note that you cannot exclude the penthouse collapses.

So, you can see that the times you quoted are in error.

If you look at the first part that hits the ground, it does take about freefall speed, about 10 seconds. However, i personally never quote this number, as the main weight of the building is not actually on the ground at this time, i like to push it back to 15 seconds just to make sure i never get accused of cheating. But that still does not exaplain how the collapse started at free fall speed, as if there was no resistance right from the beggining. I explained both these points beofre;

Originally posted by ZeuZZ

So when it started to collapse where is it getting its momentum from? it started from stationary, and momentum is Mass x Velocity, it has not yet fallen any distance, and still has the building below it supporting it, so the acceloration should start small. I do not claim that the building fell to the floor at freefall speed (as other incorrectly do, it was probably more like 12-16 seconds), only that it started its collapse at freefall speed, which is impossible, as the undamaged building below should have stopped it from even starting. Even if it did not completely stop it from starting, it should have substancially slowed it. It clearly did not. You can not have any force from momentum without initial velocity. (P = M x V). If V = 0, P always = 0. Do the maths.
[ P = momentum ]

[edit on 13-12-2007 by ZeuZZ]

Originally posted by ZeuZZ
But that still does not exaplain how the collapse started at free fall speed, as if there was no resistance right from the beggining. I explained both these points beofre;

I think if you read and dissect this paper you'll get a better idea of what was happening. Read it and get back to us with any specific rebuttals of it:

911myths.com...

Cheers.

Originally posted by jthomas

Originally posted by ZeuZZ
But that still does not exaplain how the collapse started at free fall speed, as if there was no resistance right from the beggining. I explained both these points beofre;

I think if you read and dissect this paper you'll get a better idea of what was happening. Read it and get back to us with any specific rebuttals of it:

911myths.com...

Cheers.

Actually i'm very glad that you brought that paper up, that exact paper has been pretty much directly debunked by Gordon Ross. gordonssite.tripod.com...

Gordon Ross holds degrees in both Mechanical and Manufacturing Engineering, graduating from Liverpool John Moores University, in 1984.

Basically that work has far too many assumptions in it. He has used approximations that can'not be justified.
From that paper;

He examines the energy balance within the collapse and noted that the towers were caused to collapse with very little resistance being offered by the lower structure. He makes several assumptions which are false, but more importantly he knows them to be false. These have been pointed out to him by myself and others, yet his flawed analysis remains unaltered.

He assumes that each storey of the towers has the same mass, and when enlightened to the fact that if this false assumption was removed, his conclusion would be reversed, does he incorporate this information?

He uses the full mass of the falling upper section of the tower in his analysis, and when it is pointed out that the mass which falls outside the towers footprint could not contribute to the progression of the collapse and that if this factor is taken into account his conclusion would be reversed, does he alter his report?

His published statement argues that all of the available energy of the collapse would be concentrated on crushing only one storey at a time, but later he himself acknowledges that "we suggest that,.......... a maximum of four floors would have shown any significant downward movement after impact of the upper block of floors." Does he alter his analysis to reflect this new change in thinking?

He assumes that the upper tower section remains totally intact and undamaged throughout its fall, causing the total destruction of all of the lower sections' heavier columns and floors, before then itself collapsing at full gravitational acceleration. When it is pointed out that this flies in the face of all that is known about collisions, does he alter his report?

But the real gem contained in his thinking, the argument that would have even an ardent science fiction fan throwing his arms in the air in disbelief comes from his explanation of why the towers' lower structures offered such low resistance to the collapse. In this case I will quote him directly. On March 11th he stated,

"About the picture of the fractured bolts... Has anyone considered the possibility that some bolts were never installed! That picture shows plastic deformation of the holes on the lower right, but at least two holes on the upper left look pristine - I would say they never had any bolts in them.

I have wondered about this on other photos showing failed splices on perimeter columns. Could it be the WTC collapsed so easily because it was jerry-built?"

Now this could be excused as simply an argument put forward for discussion, or maybe it was a bit of fun after arriving home from a night out at the local pub, if it was not repeated on several occasions. The very next day, when he should have sobered up, he continues thrashing in the mire of his own muddy thinking.

I suggest you find a better paper than that one. Nice try though.

reply to post by jthomas


Are you the author of that? You say "Read it and get back to us with any specific rebuttals of it:", so it's either you, or you figuratively say "us" because you are part of 911myths.com, or feel allegiance to it/them.

Seeing as Gordon Ross pretty much debunked it in its entirety, how about you have a go at trying the same on his excellent "How the Towers were Demolished" paper?

Originally posted by jthomas

As I explained carefully, the center of gravity of the top section never exceeded the edge of the building before collapse initiation. Also, although there were signs of very slow tilting long before the collapse, the collapse did not begin until the failure occurred seconds before collapse intiation as seen in all the videos.

See, for instance, youtube.com...

As I also demonstrated, WTC 2 collapsed in about 14 seconds, not 10 seconds as you state. See youtube.com...

Clearly, your speculation does not mesh with the known facts and observations.

The 23 degree outward tilt occurred over 15 minutes before the greatest majority of the South Tower was pulled into its own footprint.

I don't understand exactly what you mean in this statement: "As I explained carefully, the center of gravity of the top section never exceeded the edge of the building before collapse initiation." Exactly where are you placing a center of gravity on the leaning portion of the South Tower?

Had part of the center core not been holding the leaning portion to keep it from falling, and had the lean begun to peel from the portion of the core holding it, gravity would most probably have pulled the leaning top floors toward the ground prior to the entire balance of the building being pulled. If the bent but intact center core beams had given way at the rift, which way would the leaning section have gone? Over the edge and to the ground? Or would it have fallen inside to close the rift? The way it would have fallen is indicative of on which side of the lean the majority of mass and weight existed. Gravity would have taken over to pull it to the outside (toward the ground) or inside (closing the rift).

The 14 vs less than 10 seconds is an ongoing argument until people time it. I repeatedly did to check time and never had the timing reach 10 seconds for either building. Both towers fell in less than 10 seconds. WTC 7 fell in 6.5 seconds. The four seconds, which you tacked on at least one of the towers, is not making valid counterpoints for your argument against controlled demolitions. The immaterial four seconds appear to be a tangent to avoid scientific discussion regarding free fall under natural conditions with resistance vs unnatural conditions in a vacuum with no resistance. Controlled demolitions (implosions) are designed to deliberately create a vacuum to pull a building into itself for the purpose of a building landing in its own footprint.

Originally posted by OrionStars
Controlled demolitions (implosions) are designed to deliberately create a vacuum to pull a building into itself for the purpose of a building landing in its own footprint.

There could be some confusion with the term 'implosion' as used in demolition circles. Explosions are used to fail critical elements of the building so that the structure tends to fall in on itself but that is not caused by creation of any vacuums inside. Explosives explode IE create a rapidly propagated blast of gases which can be directed (in shaped charges) to do specific work. No blasts large enough to do the amount of continuous and intelligently propagated damage claimed can be seen or heard which is my problem with theories of controlled demolition.

AFAIK the only way to actually create localised 'vacuums' within the building would be to strategicaly plant black holes in the right places. I hope I haven't given anyone ideas for a new theory

I'm still impartial on the whole thing until sufficient solid evidence is presented to fit all the observations.

I have decided to reconsider my opinion of the WTC collapse due to the testimony of CIA agent.

click here

If al-Qaeda wasn't planning such destruction, could someone else have "helped" it along?

Originally posted by ZeuZZ

Actually i'm very glad that you brought that paper up, that exact paper has been pretty much directly debunked by Gordon Ross. gordonssite.tripod.com...

Actually, it was Gordon Ross who made faulty assumptions and his paper was easily debunked. See:

911guide.googlepages.com...

Originally posted by OrionStars

The 23 degree outward tilt occurred over 15 minutes before the greatest majority of the South Tower was pulled into its own footprint.

I'm quite happy to see your evidence of this. As there are hundreds of photos and videos of the tilting and collapses, show us some that show the 23 degree tilt being that much for a full 15 minutes.

I don't understand exactly what you mean in this statement: "As I explained carefully, the center of gravity of the top section never exceeded the edge of the building before collapse initiation."

The center of gravity of the top section would have to beyond the edge of the rest of the building below it for it to topple over.

[The 14 vs less than 10 seconds is an ongoing argument until people time it.

It's settled. Look at the video I provided. Use the timing of the video or count the seconds with a stop watch. This is a settled question. WTC 2 took around 14 seconds before collapse ended.

Cheers.

Originally posted by ZeuZZ
Theres not enough energy input to create that amount of dust that early because the only energy available to the official account is the gravitational energy. It actually takes quite a considerable amount of energy to create that amount of dust.

Do you know what the weight of the the falling top section was? That had to release quite a bit of stored energy. One other thing to remember is that the building wasn't just clean concrete floors with nothing in between them. Each floor was a full office building filled with chairs, desks, file cabinets, bathrooms, paper, and who knows how much other stuff. I'm sure all the fire-proofing insulation makes a lot of dust when you knock it loose from the beams it's insulating.


As for the exact science. It looks like the weakened steel was unable to hold up the 3.2 million pounds each floor weighed.

The gravity loads (weight) produced by the towers at their bases were on the order of 500,000 tons

-Robert Fowler, senior engineer at the structural engineering firm of McNamara and Salvia

- junior member of the WTC's engineering firm of record, Worthington, Skilling, Helle & Jackson

"With almost an acre of area for each floor and figuring about 100 pounds per square foot of area,each floor system weighed about 3,200,000 pounds."

- Jerome Connor, professor of civil and environmental engineering at M.I.T.

"At about 800 degrees Fahrenheit structural steel starts to lose its strength; at 1,500 degrees F, all bets are off"

-Eduardo Kausel, M.I.T. professor of civil and environmental engineering

Dropping one floor onto another would be asking it to double it's load from 3.2 million to 6.4 million pounds. How many floors were in the top sections that initially leaned and fell? Multiply that by 3.2 million and you'll see the magnitude of the weight the floors below were asked to hold. That doesn't even include the kenetic energy released by 3.2 million pounds moving 10 feet or so.




Scientific American - When the Twin Towers Fell

[edit on 14-12-2007 by dbates]

[edit on 14-12-2007 by dbates]

[

Originally posted by jthomas

I'm quite happy to see your evidence of this. As there are hundreds of photos and videos of the tilting and collapses, show us some that show the 23 degree tilt being that much for a full 15 minutes.

Below is a witness accounting of when the top of the South Tower lost complete support on one side. Which would definitely begin creating a very large rift by lean, from tearing apart from 3 other external support walls as one floor dropped onto another. The time indicates at least 15 minutes before collapse time the top of the South Tower had already begun to lean. The initial degree of angle from rift would depend on the distance, from the floor to the ceiling, between the floor/ceiling that dropped. The higher the upper floor/ceiling, the more initial rift degree would occur. The location of the rift was at least three floors above the impact entry hole. The alleged plane had nothing to do with the compromised floor/ceiling nor did kerosene fuel, because it was at least 3 floors below the compromised floor/ceiling.

911stories.googlepages.com...

"At 9:37, a civilian on the 106th floor of the South Tower reported to a 911 operator that a lower floor – the '90-something floor' – was collapsing." (9/11 Commission Report, pg. 304)

A lean on a top would be quite normal under cutter charge controlled demolitions. The intact top is initially used to provide the weight and mass momentum as the balance of a building has cutter charges used to release support resistance. By the time the top reaches the ground seconds later, its rubble, too, will look no different than the rest of the imploded building.

As for pancake effect, WTC 1, 2, and 7 had no pancake effect. Pancake effect literally leaves building looking like surreal layers of unevenly stacked pancakes. Some of the areas of the building will remain recognizably intact during pancake effect. Pancake effect occurs often during such natural events as earthquakes. Pancake effect collapsed buildings most certainly do not resemble what was left of WTC 1, 2, and 7 reduced primarily to dust.

The center of gravity of the top section would have to beyond the edge of the rest of the building below it for it to topple over.

You have repeated the same statement several times. What exactly do you mean using a physics explanation? Could you please explain to us exactly what you mean?

[It's settled. Look at the video I provided. Use the timing of the video or count the seconds with a stop watch. This is a settled question. WTC 2 took around 14 seconds before collapse ended.

How is it settled? Because you say it is? I repeatedly received a different result doing the same and never hit 10 seconds. I used several video sites on the Internet to test it. It may be settled for you but it isn't settled for others. Unless you can prove beyond any reasonable doubt it was 14 - no more and no less - it is not settled.

Cheers backatcha

reply to post by OrionStars


Orion....

Have you watched the complete collapse of WTC 7? If not... you have to include to collapse of the Penthouse in your timing. Why would you not?



[edit on 14-12-2007 by CaptainObvious]

[edit on 14-12-2007 by CaptainObvious]