1200 Architects And Engineers

Originally posted by exponent

Originally posted by mnemeth1
I've already debunked your utter junk science so I will not waste my time copy-pasting everything I just laid out.

You've missed a bunch of questions and you seem to think that if you damage some concrete, it vanishes from reality, so I wouldn't go crowing about your victory just yet.

However your lies about there not being 1300 certified engineers need to be addressed.

Have you actually read the page you're linking to? Just because someone else lies doesn't mean you have to repeat the lie. There are 1300 signatories including architects, psychologists, biology students. How many Mechanical, Civil, or Structural engineers are there? Not 1300 for damn sure.

Apparently you haven't read the page.

There are 1300 ENGINEERS - there are some 9000+ other signatories.

Search the page for "Supporters and A&E Students " - and you'll see where the other 9000 start.

The top section of the petition is all certified architects and engineers, which total up to 1300

Originally posted by exponent
Did you read the page? Architects are not engineers

Architects and engineers, Jesus.

Now are you going to explain why you just accused him of lying when he wasn't?

If you want to talk about peer review, let's look at who peer reviewed the NIST report first.

Originally posted by dereks

The top did not pancake the lower floors.



The top did not pancake the lower floors.

Except those pictures show it doing just that, you just posted proof of it pancaking the lower floors!

You are not looking very hard are you, or you don't understand what you're looking at? In the WTC 1 gif you can clearly see the top section collapsing itself before the bottom is even effected.

In the WTC 2 pic you can clearly see the top is at an angle. If you've ever tried to hammer a nail you would know that to make it go in cleanly and straight you need to hit it squarely, hit it at an angle and it won't go straight down. Same thing with anything that you want to go straight down through resistance, if it is at an angle it will maintain that angle (angular momentum) and continue its path. It can not change its mind and suddenly convert its force from angular to vertical. The only way the top would suddenly drop is if the resistance is removed from the bottom. Same as WTC 1 the top started collapsing before the bottom section, two independent collapses, top section, then bottom section.

reply to post by exponent

I have read all of your replies in this thread and I have a few questions regarding some of them, I hope you can help me to understand your points better.
There have been so many replies so I posted some links to your quotes here to make it easier to understand and respond to. I don't want to take these out of context.
From the above reply you quote;

Ok so we have momentum transfer (accelerating the various objects which are minimally destroyed), concrete crushing (mostly identical floor by floor with some minor differences) and yielding of steel structural elements (increasing strength as the building collapses)

What we see in the collapse videos is nothing close to "minimal destruction". What we see is in fact a complete destruction, or rather a pulverization, of all of the concrete which, I would think, constitutes for a significant portion of the accelerating mass. We also see the complete destruction of the steel and an ejection of much of this mass (both steel and concrete) outward away from the floors below which is again a significant portion of the accelerating mass.

reply to post by exponent

The question is, does the energy addition through gravity come to more than was taken in crushing, damaging and accelerating? The answer is yes, by a significant margin.

This appears as though you are claiming that Force (due to gravity) is grater than mass times acceleration. The addition of energy through gravity is equal to (not greater than) the kinetic energy that creates the destruction and acceleration of the mass.

reply to post by exponent

For every floor destroyed, a certain amount of energy is removed, then, the debris accelerates through 12 feet under gravity. This adds more energy than was taken away, that's what Bazant et al have repeatedly proven.

I know it has been stated that a debate over the conservation of energy here is difficult but I would like to bring up one blatant observation. For every floor that was destroyed much of the debris is not available to contribute to a continuing collapse scenario and thus this energy is lost to do any work in this regard.

As can be seen in many videos much of this debris is ejected horizontally away from the floors below. Furthermore much more of this debris is well above the supposed point of impact. You don't consider this as evidence that contradicts the pancaking collapse theory? I think we can at least conclude that a large portion of momentum is lost in this scattering of debris.

I wonder now is that mr. Gross guy sweat his balls off now because all this support? Now its up to 1300 and man did they get a big boost the last I checked!

Rock on people!

Originally posted by mothershipzeta

Originally posted by oniongrass

Originally posted by astrogolf
reply to post by mnemeth1

 

I like to stick with the basics. The biggest problem with your theory is that thousands of people saw two jet airliners fly into the building. It was captured by every imaginable camera angle. Here's a wager. Let's say you build a one-hundred story tall house. There's a wall around it, so nobody has access to it. No chance of anyone planting explosives in it. A 757 slams into the 75th floor. Trust me, you would try to get out. And also trust me, that it would collapse. ...

Why would that building collapse after waiting for quite a while? I don't get it. I want to stick with basics too and understand this.

Massive fires, which weakened (NOT melted) the steel supports to the extent that they could not hold the weight above them. Then, the force of the floors collapsing caused it to pancake all the way down.

The towers were designed with support in the outer walls, which would both aid an internal collapse and keep the structure relatively vertical as it collapsed.

If it had been destroyed intentionally, you wouldn't have reports like this:

As the fires continued to burn, occupants trapped in the upper floors of the South Tower provided information about conditions via 9-1-1. At 9:37 a.m., an occupant on the 105th floor of the South Tower reported that floors beneath him "in the 90-something floor" had collapsed. The aviation unit also relayed information about deteriorating conditions of the buildings to police commanders, who issued orders for its personnel to evacuate the towers. At 9:52 a.m., the New York City Police Department (NYPD) aviation unit reported over the radio that "large pieces may be falling from the top of WTC 2. Large pieces are hanging up there". With the warnings, the NYPD issued orders for its personnel to evacuate. During the emergency response, there was minimal communication between the NYPD and the New York City Fire Department (FDNY), and overwhelmed 9-1-1 dispatchers did not pass along information to FDNY commanders on-scene. At 9:59 a.m., the South Tower collapsed, 56 minutes after being struck.

After the South Tower collapsed, NYPD helicopters relayed information about the deteriorating conditions of the North Tower. At 10:20 a.m., the NYPD aviation unit reported that "the top of the tower might be leaning," and a minute later reported that the North Tower, "is buckling on the southwest corner and leaning to the south". At 10:27 a.m., the aviation unit reported that "the roof is going to come down very shortly." The North Tower collapsed at 10:28 a.m., after burning for 102 minutes.

The North Tower was hit first, but the South Tower was the first to collapse because the structural integrity was compromised on a much lower level - between the 77th and 85th floors, while the North Tower was hit between the 93rd and 99th floors. Thus, more weight to bear on the compromised supports, which were then weakened further by fires, etc.

In addition to the weakened steel (again, no one says "melted" except the 'Truthers' - complete strawman argument), the fires caused the floors to sag, which pulled in the perimeter columns and made them much less able to support the weight above.

While they were designed to support enormous static loads, they provided little resistance to the moving mass of the sections above the floors where the collapses initiated. Structural systems respond very differently to static and dynamic loads, and since the motion of the falling portion began as a free fall through the height of at least one story (roughly three meters), the structure beneath them was unable to stop the collapses once they began. Indeed, a fall of only half a meter would have been enough to release the necessary energy to begin an unstoppable collapse.

Like vertical dominoes.

"Indeed, a fall of only half a meter would have been enough to release the necessary energy to begin an unstoppable collapse."... I googled this statement that you bolded for me. The first site to pop up is Wikipedia. Your last paragraph was copy/pasterd straight from wikipedia. Now I check the source of that statement. It comes from:

Bažant, Zdeněk P.; Jia-Liang Le, Frank R. Greening and David B. Benson (2007-05-27). Collapse of World Trade Center Towers: What Did and Did Not Cause It?

ahhh, Bazant. That name sounds familiar.

I read some wiki talk about Bazant's paper:

"Everything in this section is stated as fact implying by default that supporting evidence was found. NIST stated that these claims are all assumtions to explain the collapse. They couldn't find any evidence for the extent of the column damage, nor could they find evidence for the steel deformation because there was not enough WTC steel saved to test this theory. Bazant's paper also not only mentions that computer simulations of the steel failure were not carried out by NIST because they would be (too) tedious and demanding but states that arguing the temperature of the fire and it's effect on the steel is a waste of time without it. Shouldn't the section explain this rather than excluding it?"

so back to google.I find out that Bazant/Greening got their paper published without proper peer review and favorable bias from the publisher

I just read some wiki talk about Bazant's paper:

"Everything in this section is stated as fact implying by default that supporting evidence was found. NIST stated that these claims are all assumtions to explain the collapse. They couldn't find any evidence for the extent of the column damage, nor could they find evidence for the steel deformation because there was not enough WTC steel saved to test this theory. Bazant's paper also not only mentions that computer simulations of the steel failure were not carried out by NIST because they would be (too) tedious and demanding but states that arguing the temperature of the fire and it's effect on the steel is a waste of time without it. Shouldn't the section explain this rather than excluding it?"

Also this, is Bazant a worthwhile source?forums.randi.org...

The only description of the collapse progression is FEMA's (sections 2.2.1.5 and 2.2.2.6 of FEMA Report 403 chapter 2, pp. 2-27 and 2-35 respectively). NIST dismissed FEMA's collapse initiation mechanism, not their collapse progression mechanism. Bizant's model doesn't include initiation and so does not deal with what caused initial failure.

And yet Bizant has the nerve to conclude his article with "These conclusions show the allegations of controlled demolition to be absurd and leave no doubt that the towers failed due to gravity-driven progressive collapse triggered by the effects of fire."

This conclusion steps outside the bounds of the model's applicability

Originally posted by mnemeth1
The top section of the petition is all certified architects and engineers, which total up to 1300

I wrote a quick script to search for 'str' 'civ' or 'mech' engineers, and those with 'PE' or variations thereof in their name or the lines under their name.

I came up with 396 engineers in relevant fields, although there's quite a few false positives. To your credit there are nearly 900 people with some sort of 'engineer' in their title, but this includes computer engineers etc.

So yeah there's maybe 900 less relevant engineers than you made out. You're welcome to the source code of the script if you wanna check for yourself (I was too lazy to go through them)

Originally posted by Devino
I have read all of your replies in this thread and I have a few questions regarding some of them, I hope you can help me to understand your points better

Excellent, 'new blood' as the term may be Don't worry about context, I won't assume any malice. I'll just go through what you've listed and answer them individually for now.

What we see in the collapse videos is nothing close to "minimal destruction". What we see is in fact a complete destruction, or rather a pulverization, of all of the concrete which, I would think, constitutes for a significant portion of the accelerating mass. We also see the complete destruction of the steel and an ejection of much of this mass (both steel and concrete) outward away from the floors below which is again a significant portion of the accelerating mass.

This is perhaps overstating your case. Steel was not 'completely destroyed', it was certainly destroyed, but some people claim that all of the concrete, steel etc was turned to dust which is complete nonsense. When I referred to 'minimal destruction', I was referring to the momentum transfer involved in accelerating stationary mass, rather than kinetic energy loss in fracturing/buckling elements. It was perhaps a bad choice of words.

This appears as though you are claiming that Force (due to gravity) is grater than mass times acceleration. The addition of energy through gravity is equal to (not greater than) the kinetic energy that creates the destruction and acceleration of the mass.

The first part is incorrect, F=ma, there's no real way to question it. The second part is also a little inaccurate. The addition of energy through gravity is purely dictated by mass * gravity * height lost. It is the breaking of the floors that allows this energy to be released, but it does not 'create' it in any sense.

As can be seen in many videos much of this debris is ejected horizontally away from the floors below. Furthermore much more of this debris is well above the supposed point of impact. You don't consider this as evidence that contradicts the pancaking collapse theory? I think we can at least conclude that a large portion of momentum is lost in this scattering of debris.

This analysis has been carried out, it's typically called the 'mass shedding fraction' and in Bazant's papers values of 0.2-0.5 give good agreement with visual data (collapse rate etc). Unfortunately, no reliable way has been determined to calculate the amount of mass shed, but we can estimate it to be the entirety of the perimeter columns, plus a good portion of the floor slab. I've done the calculations to work this out before but I don't have them to hand, it's around 0.35 the mass of each floor that could be ejected in a worst case scenario.

Of course then there's also subsequent ejections which may remove more of a previous impacted floor, but as I'm sure you'll agree, analysis of this is extremely difficult and hard to do empirically.

Originally posted by patriots4truth
I find out that Bazant/Greening got their paper published without proper peer review and favorable bias from the publisher

I skim read this link but couldn't see any evidence for this? Nevertheless this paper has been analysed by a number of people and it has stood up well as far as I know.

Ooh I missed this post, this is a good one.

Originally posted by bsbray11
It doesn't have anything to do with my ego.
...
What falsehoods are these again? Stop making cheap shots. I have been refuting your posts constantly, post after post, even pointing out your emotional outbursts for what they are, and this is one of those.

Yes of course, nothing to do with your ego, you're just too elite for me!

How's that recreation of the "drywall melted the steel" experiment going? All I see is a lot of time and energy spent bickering online with me. Pot, kettle.

Yes sorry I forgot the part where I believed that my government intentionally killed 3000 of their citizens. Oh wait no that's not me, that's you. It's more like the stove calling the kettle paranoid.

So if the photos were taken during the day you think it would show the WTC fires were worse?

Photos at night = brighter flames

The simplistic analysis is yours. It goes like this: 'There was steel in the building and it all collapsed! The whole building didn't fall down because it was made out of concrete!'

You ignore the fact that no, not all the steel did collapse, the steel in question had MUCH SMALLER CROSS-SECTIONS and thus wasn't comparable to the WTC steel in the first place, you totally ignore the severity of the fires which is also incomparable, the time of burn, which is ALSO incomparable, and then you don't bother giving any more reason for why it didn't totally collapsed except that it was made out of concrete. And then you say I'm the one offering the simplistic analysis when you ignore all of this? You are embarrassing yourself.

I didn't ignore all of this, your required analysis was pictures of the buildings. That was it, that's all you asked for. I have already explained to you why I chose the factors I did. Now perhaps you could explain why you ignored all of them, from both of us, and requested only pictures.

If you faced the facts you might actually be able to realize that you still have no evidence that the WTC Towers collapsed from fires and planes alone in the first place, and in the second place that you are ignoring 90% of the relevant information in these comparisons. You keep downplaying the severity of the fires. You keep ignoring the differences in the steel. You are either in denial or intentionally being intellectually dishonest about these things. And again, pointing at that the Windsor Tower's core was made of reinforced concrete is totally irrelevant because the WTC Towers' cores weren't their weakness either. And their perimeter columns were much, much larger than the Windsor Towers. We can keep going over this until it sinks into your brain matter. I guess that's what it will take. I'm not going to drop this information just because you keep ignoring it. I'm going to keep bringing it up precisely because of that, until you acknowledge it.

Please feel free to do so, it will illustrate how you are incapable of actually having a debate, and resort to simply repeating your original post.

You see, in a debate, if someone disagrees, they explain why. Once they have explained it, their opponent takes their disagreements into account, and finds a way to show they are irrelevant. In this case however, I am explaining my position as thoroughly as I can, and you are repeating your position endlessly, with no attention paid to whether it reflects reality.

The top of the Windsor Tower was fully engulfed and burned for a full 24 hours.
...
Pick any WTC fire pic you want. Do you honestly think it is equivalent to what you are looking at above? If so, like I said, you are only demonstrating your incompetence at comparing these types of things in the first place. They are obviously not equal in severity, and the difference IS extreme when you factor in the amount of time and the number of floors fully engulfed.

Why, it's almost as if you're ignoring the three factors I pointed out as being mitigating in all skyscraper fires!

"somewhat important," oh yeah, okay, right. I'll let the images speak for themselves. You have 4 or 5 times the amount of steel in the perimeter columns AT LEAST at the WTC towers to heat, with less fire, over less time. Yeah, that's "somewhat important."

Put yourself in my shoes. Your arguments are RIDICULOUS.

I'm afraid I can't put myself in your shoes, as I don't understand how you think this stuff through. You have a building which suffered a large fire and resulted in severe damage to unprotected steel, wheras the protected steel survived quite well. Despite this, you seem to be focusing on the thickness of the steel as being the important factor. Are you not capable of seeing the difference in this tower? The fireproofed steel survived, not amazingly of course, but it survived. The non fireproofed steel failed quickly. I don't mean to repeat myself, but I thought I would try and point it out again.

You still have no proof of what the WTC failure mechanism was. You keep falling back on nonsense that was never proven in the first place. Do you think this is a religious debate?

Just because you choose to ignore evidence doesn't mean it does not exist. You can pretend that NIST had all sorts of imaginary motivations (and you do) while carrying out their tests, but you can't refute them, and so you just attempt to throw mud on them. We've already been through this too btw (not exactly a surprise)

Like the fact that the Windsor Tower wasn't demolished? There's one factor that allowed it to continue standing.

Epic burn.

Let me guess who gets to determine that. You?

You think the Windsor Tower fire is not an extreme difference than the WTC fires? Being fully engulfed on those floors and burning for 12 times as long? What is an extreme difference if not that?

Extreme differences would be large differences in fire loads, flammable compounds, accelerants. Do I have to start detailing the basics of fire science to you now as well?

Yeah, I guess they should have built the WTC Towers out of wood. That's where they went wrong. You got me. What was I thinking?

Wow sarcasm, it's as if you don't have a good comeback but you feel you need to respond to every bit of my post. Oh no, now I am doing the same!

No, the problem is that they never tested their hypothesis, for the point of testing their hypothesis. They would have to have set up exactly what they did to calibrate their computer simulations. Why didn't they do it again to reproduce their hypothesis physically? Because they're too genius for that? Is that how your kind of "science" works? Let me guess, "yes." Sorry. Science is not based on condescension. You still have to show your work, even NIST.

So, you haven't even read the report in depth enough to realise what portions they were testing. This is no surprise.

Is that what I said? Is that what was necessary to calibrate their computer simulations?

No, what was necessary is what they did. I'm asking what you want

Why do you think it's impossible for a single truss to be isolated and reproduce the pulling on the perimeter column? Would you like to explain the technical "reasoning" behind that one for me?

It's not, that's exactly why I asked you to describe the test you would like to see. Perhaps we can get the money together to conduct it. I'd hate to see your face after it was completed though

reply to post by exponent

When I referred to 'minimal destruction', I was referring to the momentum transfer involved in accelerating stationary mass, rather than kinetic energy loss in fracturing/buckling elements.

OK, I believe I understand your point here as this is pretty clear but there is quite a lot of ambiguity pertaining to what this mass is doing at the point of collapse/energy transference.

Of course then there's also subsequent ejections which may remove more of a previous impacted floor, but as I'm sure you'll agree, analysis of this is extremely difficult and hard to do empirically.

Here I agree with you but I also don't think we can dismiss this loss of kinetic energy that is being ejected and then use it in a collapse/energy transference scenario. Some energy is lost here as well as some energy is lost during momentum transference, i.e. destruction. The question is, how much?

It is obvious that there is a considerable amount of kinetic energy lost here in the ejection of material that is therefore unable to do work in a collapse propagation of the floors below. There might also be a lot of kinetic energy lost in the transference of momentum during the destruction of the undamaged floors below. The problem here is this momentum transference is pure speculation at this point. If there is a transference of energy in this manner wouldn't we see a noticeable deceleration? Keep in mind the first statement in this paragraph.

This analysis has been carried out, it's typically called the 'mass shedding fraction' and in Bazant's papers values of 0.2-0.5 give good agreement with visual data (collapse rate etc).

Sorry I am not familiar with this lingo, as it were. By 0.2-0.5 does this mean 20%-50%?


I quoted, "This appears as though you are claiming that Force (due to gravity) is grater than mass times acceleration."

The first part is incorrect, F=ma, there's no real way to question it.

What is incorrect, my statement or my observation to your claim?


I then quoted, "The addition of energy through gravity is equal to (not greater than) the kinetic energy that creates the destruction and acceleration of the mass."

The second part is also a little inaccurate. The addition of energy through gravity is purely dictated by mass * gravity * height lost. It is the breaking of the floors that allows this energy to be released, but it does not 'create' it in any sense.

Gravity is the only force accelerating the mass here that I can think of. It is supposedly the transfer of kinetic energy, or momentum, that is creating the destruction of and subsequently accelerating of this mass, is it not? I don't mean energy is created, I mean destruction is created by said energy. My question is in your statement that more energy is present in the falling mass from gravity than is used in "crushing, damaging and accelerating" of said mass.

I would like to point out that this transference of energy that is said to be causing this destruction, acceleration and collapse of the undamaged floors is, at this point, pure speculation. I believe it is still yet to be proven that this is what's taking place. Here we could just as easily speculate that all of this is being caused by the addition of energy by way of explosives.

reply to post by bsbray11


*Whhoooooshh!!!!!*
Thats is the sound of what I typed to you flying waaaayyy over your head right now.

In your entire response, i fail to see one mention about the ever so important light steel trusses that made up the floors of the WTC. Why did you ignore this and jump on the exterior columns again, when I distinctly said IT WAS A COMBINATION of every point including the exterior columns and floor trusses acting together and reacting from the fires and such.

What you are looking at could be the result of incendiaries or some other failure mechanism or just about anything. The PROOF that this is showing NIST's hypothesized failure mechanism, is non-existent. They never showed that their failure mechanism was possible in the first place. They just said it was and that it caused what happened. You would have to be dense to think looking at the building is proof of the NIST report when NIST never showed you what their mechanism would actually look like in the first place

Oh really? Pray tell, what magical incendiaries you are dreaming of to create this affect other than the fires themselves? Did you bother at all into looking into the fire studies about the behavior of light steel trusses in fires? Well because if you did (but I know you didnt) you would have learned that light steel trusses are VERY dangerous structures in fires. They have a tendancy to fail and collapse when they expand and sag from the fires, causing roofs to collapse (in the most common use of these trusses). At least for NIST and others (including fire depts, fire rating analysts, fire investigators) use their knowledge of how buildings and building materials behave in fires and used that same knowledge in observing and giving a very good theory and that is based and rooted in facts and observed events. I'm sorry but there is a BIG difference between having facts backing a theory, and dreaming of planted magical incendiaries that were powered by pixy dust or whatever as the main cause of the collapses of the WTC. What evidence do you have of incendiaries causing the observed effects? Any will do. I mean to be honest, you are basing your assumptions or opinions on far less than what NIST came up with. Far far faaaarr less. I mean really. NIST at least did actual tests of steel, columns, trusses and added the results together and compared them to the observed events happening to the WTC prior to collapse. And guess what? Its pretty damn accurate, but of course nothing is 100%. What did the TM do? Huff and puff and furrow their brows, and with a heavy dose of incredulity, in essence, state that, "No! NIST is wrong because there is no way that could have happened!" But you know what? I'll take their results over the TM's magic incendiaries causing the collapses, when I cant even get a straight line of events of who, what, when, how, where, from anyone in the TM who believes this rubbish.

By the way, how is their failure mechanism not possible in your opinion? I mean what qualifies you to make that statement, if you ignored completely the trusses? You dont know that light steel trusses are major hazards in fires? You dont know that the sheering effects of a sagging truss will do some serious structural damages to the surrounding structure it's connected to? Why do they have to show YOU that it's possible if you cannot extrapolate the data yourself and see just how it is?

And its funny how you ignored the size of the trusses, when making the comparison to Windsor Tower's steel structure. I mean wow. The trusses are even thinner than the steel that was on WT. I was not making the comparison of the WT's steel to WTC's exterior columns, no no. Pay attention when you read. I was talking about the trusses in comparison to WT's steel.

This is ignored because there is absolutely no evidence that this garbage ever happened to begin with. When you prove it, it will be considered. Until then, if you want to back a theory that has never been conclusively proven, you might as well side with demolition theory because it has more corroboration going for it than NIST's superficial assertions of a visual-match, like I said, despite their ever showing you what their mechanism would look like in the first place.

*facepalm*
No evidence??


Right, and the fact that we SEE the floor trusses sagging inside the tower and have reports of it happening from pilots hovering next to it, we see the exterior columns bending INWARDS prior to initiation of collapse, we hear and see reports from pilots mentioning how the Tower was beginning to tilt to one side, that all is not evidence of what NIST and I am saying that happened??

Wow, and somehow to you and the TM, all you needed was to hear people mention something "sounded like a bomb!; it sounded like a boom!; it went boom!; I heard a boom; I heard an explosion" and viola! That is AMPLE proof of bombs and demolition at WTC. Oh yeah and pictures of the buildings already underway in collapse as "evidence of demolition charges". Well maybe you can direct me to the magic incendiary that can burn silently and then explode silently to take down large buildings. Or was it plain ol demo charges? Or was it magic paint on nano nano thermite?? Or was it some super duper sekrut explosive that needed the super nanu nanu magic thermite as a fuse for it??? I mean come now, bsbray, you expect me to believe that THIS is much more corroboration than NIST's reported events?? I think I'm gonna need a drink after this doozy!

A quick warning before I write the rest of this reply. I've had a few drinks by this point and so my response may not be as coherent as I would hope!

Originally posted by Devino
OK, I believe I understand your point here as this is pretty clear but there is quite a lot of ambiguity pertaining to what this mass is doing at the point of collapse/energy transference.

There's no doubt that is true. Here are the major factors that have been taken into account in the Bazant papers, and I consider to be an accurate summary (not in order of magnitude)
1. Mass acceleration
2. Air explusion
3. Concrete crushing (referred to as communition)
4. Plastic deformation of columns

Of course, this is hardly unambiguous, but as very little information can be gathered directly, these are simplified assumptions which help with attempting analysis.

Here I agree with you but I also don't think we can dismiss this loss of kinetic energy that is being ejected and then use it in a collapse/energy transference scenario.
...
It is obvious that there is a considerable amount of kinetic energy lost here in the ejection of material that is therefore unable to do work in a collapse propagation of the floors below.

So far this is accurate, I cut out a question you asked and will try and answer it below.

There might also be a lot of kinetic energy lost in the transference of momentum during the destruction of the undamaged floors below.

This kinetic energy is not 'lost'. If we are talking about purely the acceleration of the various components of a floor after the floor has been destroyed, this floor (minus the mass shed) becomes part of the upper block, the 'piledriver'. Therefore the kinetic energy imparted is still available to do work as the next floor down is impacted.

The problem here is this momentum transference is pure speculation at this point. If there is a transference of energy in this manner wouldn't we see a noticeable deceleration? Keep in mind the first statement in this paragraph.

If the towers failed as this paper suggests then we probably should see a 'jolt' as it is referred to. In Bazants papers he treats the towers as failing over a single floor, with the resultant impacts being symmetrical and even. In reality however the tops of the towers tilt, and very few direct column to column impacts will occur. Bazant's analysis is biased in favour of collapse halting, in order that a result of collapse propagation is more convincing. (in theory!)

Sorry I am not familiar with this lingo, as it were. By 0.2-0.5 does this mean 20%-50%?

Yes.

What is incorrect, my statement or my observation to your claim?

I don't want to say either, I didn't mean to imply that F != ma, I accept that it does, and I'm not sure where the ambiguity arises from.

Gravity is the only force accelerating the mass here that I can think of. It is supposedly the transfer of kinetic energy, or momentum, that is creating the destruction of and subsequently accelerating of this mass, is it not? I don't mean energy is created, I mean destruction is created by said energy.

I have no problem with this, I guess we misunderstood each other.

My question is in your statement that more energy is present in the falling mass from gravity than is used in "crushing, damaging and accelerating" of said mass.
I would like to point out that this transference of energy that is said to be causing this destruction, acceleration and collapse of the undamaged floors is, at this point, pure speculation. I believe it is still yet to be proven that this is what's taking place. Here we could just as easily speculate that all of this is being caused by the addition of energy by way of explosives.

The problem is with this sort of speculation, that it is not limited to explosives. If we are free to speculate about things we have no evidence for, we could suggest a million tiny leprechauns were attacking the steel for years, and finally gave way just coincidentally at the right moment!

Just because a theory may sound plausible does not mean it's likely or even possible. The important thing about Bazant's analysis is that it provides a mechanism by which the towers could have collapsed, without requiring a whole new theory to be produced.

What I mean by that is that we already know that the buildings were on fire, that they sustained impact damage, and that the failure mechanism was a wall failure leading to a tilt. From that, Bazant's analysis follows using only physical principles, without requiring the existence of any extra inputs.

For the explosive argument, these calculations would still have to be done, but the differing results that would (presumably) be gathered must then be analysed to determine the mechanism of explosive demolition. It would require more work and be more complex.

Because of this, Occam's Razor applies, until any new evidence is brought to light which cannot be explained by the theory we are discussing.

Hope this corrects any ambiguities and clarified my position. I've asked the moderators for the potential of a moderated question/answer thread, and I feel that some of your questions would work well in such a setting. Feel free to continue posting them or PMing me if I miss some etc.

Originally posted by GenRadek
*Whhoooooshh!!!!!*
Thats is the sound of what I typed to you flying waaaayyy over your head right now.

Really?

That's cute.

In your entire response, i fail to see one mention about the ever so important light steel trusses that made up the floors of the WTC.

Well if you read my post you'd realize that's because they are irrelevant. Let me guess... they sagged and pull the perimeter columns inward? That's what NIST said. So I ask, where's NIST's proof? Uh oh! *Whhhoooooosshhh!!!* There's that sound again!!

Oh really? Pray tell, what magical incendiaries you are dreaming of to create this affect other than the fires themselves?

Wait a minute, fires melt steel now?

I don't know about magical, but there are plenty of other technologies you could educate yourself about.

I appreciate all the time you must have put into the rest of your rant about pixie dust and Peter Pan, but I'd rather wait until you show me the evidence for NIST's hypothesis before debunking children's stories.

reply to post by exponent

However, this is not to be applied in a general sense between two complex bodies, it applies purely to the molecules the substance is made from. An easy way to show how this is wrong is to assume for a second the forces balance as Chandler says. In that case we know that net force would be 0, and as mass is positive, the only other variable is acceleration, which must be 0 in this case.

If a net force F is applied through the center of mass of a body such as the top section of a twin tower the resultant acceleration will equal F divided by its mass. F=ma does apply. If the net force acting on the top section is zero, acceleration will also be zero, this was the exact situation before the top section had started to fall, what is the problem with it?

This is the original video I had seen and contains the most egregious mistake that people appear to be repeating. At about 1:30 into the video Chandler claims two things.
1. The force applied by the upper block, and the force applied by the lower block are identical.

...

The forces between the various impacting parts certainly can be stated to be equal, but a force represents only a potential to do work,

The downwards force of the top section crushing the lower section is equal and opposite to the upwards force of the lower section resisting collapse. This is not a mistake, its a necessary physical law. Force is related to work by force times distance equals work.

It is not true however, in fact it is perfectly possible for the acceleration to increase during the period of collapse. If the mass is high enough and the energy expended in breaking objects low enough then the following will happen.

Due to the hugely safe way in which structures are designed it would be (imo) extremely difficult, if not impossible, to find a properly designed structure which has such high mass and such low strength, that it could accelerate through itself at ~2/3rds free fall, or nearly any acceleration for a sustained period of time.

If the mass is high enough and the energy expended in breaking objects low enough then the following will happen. As each floor is impacted, some energy will be consumed and removed from the upper block's kinetic energy, however, the resultant mass which has been added will then be accelerated under gravity before it impacts the next floor. If the mass gain is great enough to offset the energy loss, then the rate of acceleration will increase as the building collapses.

I agree with this statement. If what you had just described was true for the towers, it would be safe to expect to see the rate of acceleration slowly build and increase as the building collapses. Instead we saw an almost instant onset of ~2/3rds free fall acceleration and no further build up of acceleration as mass increased.

Chandler addresses none of this, and his presentation of the physics involved is far too simplistic and involves too short a measurement period to make predictions about the whole collapse.

The reason it is over a short period is because in that video he is investigating what happens to acceleration as the initiation section is crushed and undamaged structure starts being impacted. One would expect to see some sort of difference, as there was obviously a huge difference in the structural resistance of the heavily damaged initiation section and the undamaged lower structure.

This is true, and vector addition can be used to determine the tension forces on the strings, but you would find that the closer they are to vertical and the more equal the tension, the faster the failure would occur. In WTC7, all columns were vertical and so this analogy doesn't really hold up that far, although we do see the effects in that the penthouse collapses prior to the outer walls.

Making them close to vertical on top of each other just makes them the equivalent of a single member. To compare the analogy to WTC7 I would arrange the strings vertically spaced apart with a rigid board supporting the mass, like this:

|_|_|_|_|_|

The strings are then cut one by one, in order, starting at one side, until progressive failure ensues (the tension equivalent of the WTC7 compressive failure):

__|_|_|_|

The left hand side should start to fall ahead of the right hand side.

If it was legitimately weakened to the point where it was providing the same resistance to collapse as a structure made of marshmallows then what was it waiting for?

There's always going to be a point that weight overcomes carrying capacity, it took only a few seconds once the east penthouse collapsed into the building for the global collapse to begin, and it does quickly progress. I'm not understanding the criticism here.

What I meant was this. For the structure to free fall through about 8 stories requires about 8 stories worth of equivalent non-existent structure. If a horizontal progressive collapse started at one side of the structure, creating 8 stories worth of non-existent equivalent structure in that zone, and progressed across to the other side of the structure, why (or how could) everything wait until horizontal progression had effected every last part of the structure before failing. In other words, why didn't the first 8 stories worth of non-existent equivalent structure "zone" fail when horizontal progression was only say, half way across the structure. If this happened we would have seen (looking at the exterior structure) one side begin to collapse ahead of the other side of the structure, like in the analogy above.

The part that he forgets to mention is that shortly after the 'free fall portion' has completed, the building impacts and still accelerates for a few sample periods.

It accelerates for about one level, at 25% of the original acceleration. I would expect to see some sort of change in acceleration in the towers as the top section impacts undamaged lower section, as there must be some difference between the heavily damaged initiation zone and undamaged structure, in terms of ability to resist collapse.

It is because the internal frame has already failed that the acceleration is so great, the building at that point was being held up by the minimal strength of the external walls and what structural elements did not fail due to the east penthouse collapse.

How much of the building did the outer structure still have to support? From what I gather, it sounds like vast majority of the inner building has already collapsed, resulting in a birdcage-like outer structure (which would obviously be unable to free fall through itself).

If this is the case, why did the east penthouse collapse 6 seconds before the start of the global collapse, and why do microphones that clearly pick up the collapse, not pick up any explosive sounds?

It's been proven that NIST edited the audio and video of a lot of footage. I've seen a raw video which had the explosive sounds. There were many witnesses reporting explosive sounds at various points. Final member severing could also be done with thermite type cutting charges.

While I was looking at the Chandler videos I noticed these little gems:



Pretty definitive proof of a cutter charge in the corner column. How does a puff of air do that?



This projectile changing direction in mid-air is interesting. I can't think of any non-sinister explanation to this.

reply to post by exponent

From my quote, "There might also be a lot of kinetic energy lost in the transference of momentum during the destruction of the undamaged floors below."

This kinetic energy is not 'lost'. If we are talking about purely the acceleration of the various components of a floor after the floor has been destroyed, this floor (minus the mass shed) becomes part of the upper block, the 'piledriver'. Therefore the kinetic energy imparted is still available to do work as the next floor down is impacted.

Yes, this is a mistake on my part. I don't mean lost as in missing but used up in the transference of momentum and unable to be considered in the continued collapse/destruction sequence at the same rate of acceleration.

At the time that this kinetic energy is transferred into the destruction of the floors below it is being used and cannot contribute to additional acceleration yet it can be regained through the force of gravity over time. I use the word "lost" to imply that it cannot be used at the same time to explain the observed rate of acceleration. I think this is important because I see that this kinetic energy, as well as that of the ejected mass, appears to be used to explain the rate of collapse, or destruction of the lower floors, steel columns, etc..., and the rate of acceleration at the same time.

I made this statement, "I would like to point out that this transference of energy that is said to be causing this destruction, acceleration and collapse of the undamaged floors is, at this point, pure speculation."

The problem is with this sort of speculation, that it is not limited to explosives.

I agree with this statement yet I don't want to get too carried away with wild speculation. We know that these buildings came down and we agree that there is a lot of ambiguity that pertain to what the upper mass is doing during the collapse. I feel that it is more than fair at this point to entertain other reasonable explanations for collapse propagation.

One reasonable explanation would be, of coarse, a gravitational collapse by way of kinetic energy transference that does the destruction and acceleration of all the mass. Another reasonable explanation I believe is with the use of explosives. Again I think it is at least fair to entertain both of these theories and not just focus on one or the other.

For the explosive argument, these calculations would still have to be done, but the differing results that would (presumably) be gathered must then be analysed to determine the mechanism of explosive demolition. It would require more work and be more complex.

I totally agree here and my point is that I feel that this does need to be done. I don't understand how this would be carried out so I will have to leave it at that.

Because of this, Occam's Razor applies, until any new evidence is brought to light which cannot be explained by the theory we are discussing.

This is a reasonable point yet the problem is that it can also be used as a catch 22 situation. There is a lot of evidence that seems to show proof of explosives that has been presented over the years yet can it be explained with the official theory? Some might say that it is the nature of a purely gravitational collapse yet others might say that it looks rather like the signs of explosives having been used.

After reading your replies in this thread I have gained an understanding into how a purely gravitational collapse could have ensued yet there are other blatant observations that I would not like to ignore. In order to recall these observations I will do something I normally do not do, quote myself.

Is there any evidence of explosives having been used that cannot be explained by the official theory? I listed several in the post I made Here with this question.

• -Eyewitnesses claiming to have heard explosions before collapses of all three towers.
  
• -Recordings of these claimed explosive sounds before collapse of all three towers including actual commentary from some of the eyewitnesses.
  
• -Eyewitnesses claiming to have seen molten steel from at least one tower before and after collapse.
  
• -Video confirmation of molten steel from at least one tower before and after collapse.
  
• -Eyewitnesses claiming to have heard explosions during collapse of all three towers.
  
• -Video confirmation of explosive sounds during collapse of at least two towers.
  
• -Video confirmation of explosive squibs seen in all three tower collapses.

...
From this perspective I see what appears to be a lot of evidence in favor of explosives used in the collapse of all three WTC towers and I haven't even mentioned the physical evidence.
Was there thermite residue found in the dust from these towers?
How about the pulverization of just about everything that was once inside those towers; concrete, steel, sheet rock, people, computers, etc...
Or the cut beams and steel slag found in the debris?
How about the melted and even evaporated steel found in the debris?
Was there thermite residue found on some of these steel beams as well?

I just noticed that I hint at a pulverization of steel in that quote, oops.
I then asked if all of these could be explained by a purely gravitational collapse without any response.
As for evidence of molten steel that was seen and video taped I compare it to a thermite reaction (video linked below) found in This post.

Google Video Link

As for the sounds of explosions during the collapse of WTC 1&2, which cannot clearly be discerned, I attempt to make a comparison of the sound these two towers made to a firecracker roll (16,000 count) in the video below found in This post.


This, in my opinion, is more than enough evidence to at least suggest the use of explosives in the collapse of all three towers and therefore gives good reason to consider an explosive demolition theory. I think it has been pointed out that no official investigation has looked into the possible use of explosive in the collapse of the WTC towers and the question remains, why not?

Even if I were to believe that it has been proven that it is possible for a purely gravitational collapse this last question screams out at me and I would find myself rethinking this whole scenario.

reply to post by bsbray11

Oh so you need "PRRRROOF!!" of what NIST observed and tested and came to the logical conclusion based on observed events and corresponding data gathered from actual tests that were controlled to mimic as best as possible to the actual events? Whats your version or reason for seeing what happened?

Oh come now, well what else was pulling the exterior columns inward? Gremlins? Magic implosion devices that slowly and surely explode in slow mo, creating a slow vacuum that pulls in the exterior columns? Or maybe it was invisble giants pushing on the exterior columns? Where is NIST's proof? It happened! Right there in your face on the video and in front of thousands of eyes. Combine observed effects of the floor trusses sagging and exterior walls bending inwards, with experiments that do indeed confirm the effects, and you have a pretty accurate outcome that matches closely with what happened. Dont tell me you dont know how experiments and real scientific tests work. But then again the only thing you probably saw closest resembling "science" was "Dr." Jones' pathetic rag of a paper that is so filled with errors it would make a high school chem teacher cringe. Or Richard "The Boxboy" Gage with his magic boxes representing the WTC. I mean if this is the level of scientific research you are subscribing to, I'd reccomend you reconsider which side you want to argue for. What, do you have a better version? Does it include magic nanu-thermite laced with pixie dust?

Wait a minute, fires melt steel now?

I said that? Where? Please show me, cause what i did recall saying is this: "Oh really? Pray tell, what magical incendiaries you are dreaming of to create this affect other than the fires themselves?"
Oh, by the way, who did start that lie that steel melted? A truther! So why are you parroting a lie and mixing that into the actual truth? I suggested no such thing, and apparently you cannot get over the fact that fires can soften steel and cause it to expand causing sheering stresses on the surrounding structure, adversly affecting the whole thing and even cause collapse.

What NIST had was a theory. You do know what a theory is? A theory is dervived from a hypothesis. What the vast majority of 9/11 truthers have is ideas and hypothesis. Hypothesis is an educated guess. Heh, 99% of what the truthers do is guess from watching yt videos.

A hypothesis is an educated guess, based on observation. Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven, but not proven to be true

A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it. Therefore, theories can be disproven. Basically, if evidence accumulates to support a hypothesis, then the hypothesis can become accepted as a good explanation of a phenomenon. One definition of a theory is to say it's an accepted hypothesis.

chemistry.about.com...

Well lets see, NIST has an actual hypothesis that has been tested and found valid, and compared to the actual events. So it is a theory. And an accepted theory by the many who worked on the investigation. So where is the TM's tested hypothesis? I mean besides the dilligent sluething of countless Youtube videos and criticiszing and analyzing blurry photos and cherry picking eyewitness accounts? Or salivating over a very poorly written "experiment" with many many many flaws both procedural and recording of data?

But hey you know, I still know that you didnt really read the NIST paper I posted, because all your questions are answered in there. If only you understood what you read and apply it to the observed events.

But no really, whats your version of events that could have caused the gradual inward buckling of the exterior columns and the sagging of the floor trusses? Yes remember the floor trusses? The same floor trusses that firefighters call deathtraps in fires? Are you going to address the light steel trusses? And no, saying they are irrelevant because YOU say so is not an answer. Its just the lazy way out of giving me a serious answer. What is the matter? Cant explain it, so best to ignore it? The usual MO of the TM?

Originally posted by Azp420
If a net force F is applied through the center of mass of a body such as the top section of a twin tower the resultant acceleration will equal F divided by its mass. F=ma does apply. If the net force acting on the top section is zero, acceleration will also be zero, this was the exact situation before the top section had started to fall, what is the problem with it?

The problem is that from my perspective, Chandler is using newton's third law to argue that the force applied by the lower section is suspiciously low. He's not taking into account the fact that the collisions and newton's third law apply to the actual contacting parts, and that the upward force must be much higher for things like column impacts, even if they cannot survive the impact. This is not detectable in his data, and he does no analysis to determine whether it would be.

The downwards force of the top section crushing the lower section is equal and opposite to the upwards force of the lower section resisting collapse. This is not a mistake, its a necessary physical law. Force is related to work by force times distance equals work.

Again this is an inaccurate simplification of the situation occurring. The whole top section is not accelerating downwards through a homogeneous block. It is the individual elements the forces are applied to, and this is why energy must be considered.

Due to the hugely safe way in which structures are designed it would be (imo) extremely difficult, if not impossible, to find a properly designed structure which has such high mass and such low strength, that it could accelerate through itself at ~2/3rds free fall, or nearly any acceleration for a sustained period of time.

The WTC towers were designed to be as light as possible, they were the tallest buildings in the world for a period. Not only this but their design results in almost no chance of direct column to column collision unless the entire floor's worth of column are destroyed instantaneously. Their design basically makes this failure mode hard to avoid.

I agree with this statement. If what you had just described was true for the towers, it would be safe to expect to see the rate of acceleration slowly build and increase as the building collapses. Instead we saw an almost instant onset of ~2/3rds free fall acceleration and no further build up of acceleration as mass increased.

The sample rate isn't long enough to say whether the acceleration increased really, nor is the measurement mechanism that accurate. It's not easy to make predictions about later in the collapse that can be tested, because it is true that the top block is quickly obscured by dust.

The reason it is over a short period is because in that video he is investigating what happens to acceleration as the initiation section is crushed and undamaged structure starts being impacted. One would expect to see some sort of difference, as there was obviously a huge difference in the structural resistance of the heavily damaged initiation section and the undamaged lower structure.

'One would expect'. I take issue with this, as the supporting analysis has been criticised repeatedly (the 'missing jolt' paper that used a mechanism incapable of detecting even artificially created jolts in the input data). Perhaps intuitively you would think so, but without analysis it is nothing more than a guess I'm afraid.

Making them close to vertical on top of each other just makes them the equivalent of a single member. To compare the analogy to WTC7 I would arrange the strings vertically spaced apart with a rigid board supporting the mass, like this:

|_|_|_|_|_|

The strings are then cut one by one, in order, starting at one side, until progressive failure ensues (the tension equivalent of the WTC7 compressive failure):

__|_|_|_|

The left hand side should start to fall ahead of the right hand side.

This is indeed what happens to the interior structure, that's why you see the penthouse fail from east to west. Once enough damage was caused though, self weight becomes an issue with the surviving sections. At least, that is my understanding of NISTs analysis. Unfortunately a similar analysis as to WTC1/2 has yet to be carried out with WTC7.

What I meant was this. For the structure to free fall through about 8 stories requires about 8 stories worth of equivalent non-existent structure. If a horizontal progressive collapse started at one side of the structure, creating 8 stories worth of non-existent equivalent structure in that zone, and progressed across to the other side of the structure, why (or how could) everything wait until horizontal progression had effected every last part of the structure before failing. In other words, why didn't the first 8 stories worth of non-existent equivalent structure "zone" fail when horizontal progression was only say, half way across the structure. If this happened we would have seen (looking at the exterior structure) one side begin to collapse ahead of the other side of the structure, like in the analogy above.

There's a couple of problems with this. The first is that 'non-existent structure' is not accurate. The acceleration reported is a best fit line through some quite noisy data, that's based on a low accuracy source. We know that even in controlled demolitions (as Chandler demonstrated) the acceleration is not equal to g, and we know that there's no mechanism to actually remove all of the mass from 8 stories.

The reason that the collapse initiation was so quick once the penthouses had begun collapsing is that the self weight overcomes the carrying capacity of the exterior structure. You will remember that there is a 'kink' in the exterior wall, so this surely satisfies what you would be looking to see, one section of the building failing ever so slightly quicker than the rest?

It accelerates for about one level, at 25% of the original acceleration.

It would seem that using his own logic then that is proof that the section it was impacting was being demolished and the upper block was not demolishing it.

In reality, the section that is being impacted has been damaged intentionally, but it is being destroyed by the upper block. In this case the energy requirement is high enough to slow the acceleration, but not enough to stop it entirely. It is only when the upper block impacts more intact floors that you see the deceleration. This is exactly the mechanism I have been trying to illustrate, but with much higher capacity to resist collapse.

I would expect to see some sort of change in acceleration in the towers as the top section impacts undamaged lower section, as there must be some difference between the heavily damaged initiation zone and undamaged structure, in terms of ability to resist collapse.

I'm sure there is, but as I've mentioned before, the collapses covered at least 2-3 floors at once, meaning that any sudden 'jolt' would be averaged out.

How much of the building did the outer structure still have to support? From what I gather, it sounds like vast majority of the inner building has already collapsed, resulting in a birdcage-like outer structure (which would obviously be unable to free fall through itself).

We know some of the internal framing did survive, but not a gigantic amount, bear in mind that the upper section of the internal frame is still connected to the exterior, and is what is forcing its failure. There are approximately 8 floors of critically damaged components, unable to provide measurable resistance (using our inaccurate data) but the rest clearly provided lots of resistance. This building was designed as a 'grid', unlike the WTC towers.

It's been proven that NIST edited the audio and video of a lot of footage. I've seen a raw video which had the explosive sounds.

You have? Link please?

While I was looking at the Chandler videos I noticed these little gems:

I don't see anything particularly strange here? Two huge sections of building are impacting each other, and some debris and air is expelled as a result of this. I must say I don't have audio at the moment so if he's making some brilliant point I am missing it.

Pretty definitive proof of a cutter charge in the corner column. How does a puff of air do that?

I am also missing the point here, what exactly is suspicious? I will have a look at these with audio in a bit.

This projectile changing direction in mid-air is interesting. I can't think of any non-sinister explanation to this.

Didn't see this either, but it's hard to check without audio. Still I can think of an explanation, one piece of debris breaking into two. As long as the vectors add up then you can easily have things change direction. Without watching it though it's hard to make any claims

Originally posted by Devino
Yes, this is a mistake on my part. I don't mean lost as in missing but used up in the transference of momentum and unable to be considered in the continued collapse/destruction sequence at the same rate of acceleration.

Sure, I still don't entirely like your wording but I think we agree on this topic so I won't be a complete pedant

I think this is important because I see that this kinetic energy, as well as that of the ejected mass, appears to be used to explain the rate of collapse, or destruction of the lower floors, steel columns, etc..., and the rate of acceleration at the same time.

I'm not sure who you think is using this, because I don't know of any analysis that re-adds the energy used up damage.

I agree with this statement yet I don't want to get too carried away with wild speculation. We know that these buildings came down and we agree that there is a lot of ambiguity that pertain to what the upper mass is doing during the collapse. I feel that it is more than fair at this point to entertain other reasonable explanations for collapse propagation.

I don't mind entertaining other theories, but as you noted below we need to actually get some evidence to support them.

This is a reasonable point yet the problem is that it can also be used as a catch 22 situation. There is a lot of evidence that seems to show proof of explosives that has been presented over the years yet can it be explained with the official theory? Some might say that it is the nature of a purely gravitational collapse yet others might say that it looks rather like the signs of explosives having been used.

The problem still remains that many of these 'signs of explosive' are things as innocuous as air being ejected from a floor being crushed, or the sounds of explosions being heard in a fairly huge office fire. These sorts of things are explainable by both theories, but require no new information or explanation to be explained by 'damage and fire theory'.

From this perspective I see what appears to be a lot of evidence in favor of explosives used in the collapse of all three WTC towers and I haven't even mentioned the physical evidence.

It is at this point I realise I've left this tab open overnight without finishing the post. I'm sorry about that. All I was going to say about this quote is that other than the 'molten steel' which was likely other elements, the rest of your evidence is basically down to speculation or suspicion. It's not something I can prove to you, you just have to determine where the balance of evidence lies.

I hope I haven't missed anything, but I only just woke up so don't hate me if I did!

reply to post by exponent

The problem is that from my perspective, Chandler is using newton's third law to argue that the force applied by the lower section is suspiciously low. He's not taking into account the fact that the collisions and newton's third law apply to the actual contacting parts,

It shows the net force being applied to the top section averaged from measurements taken at 2/10th second intervals. Individual member forces are obviously not being measured, with the force in some members and at some points in time exceeding the net force. I would still expect to see some sort of difference between the net resistance provided by the initiation zone and the undamaged structure.

Due to the hugely safe way in which structures are designed it would be (imo) extremely difficult, if not impossible, to find a properly designed structure which has such high mass and such low strength, that it could accelerate through itself at ~2/3rds free fall, or nearly any acceleration for a sustained period of time.

The WTC towers were designed to be as light as possible, they were the tallest buildings in the world for a period.

Light and strong?

The sample rate isn't long enough to say whether the acceleration increased really, nor is the measurement mechanism that accurate. It's not easy to make predictions about later in the collapse that can be tested, because it is true that the top block is quickly obscured by dust.

There's another video showing the whole collapse where Chandler programed a line to accelerate at the same rate as the top section then maintain that same rate when dust obscured everything. The acceleration did not increase.

There's a couple of problems with this. The first is that 'non-existent structure' is not accurate. The acceleration reported is a best fit line through some quite noisy data, that's based on a low accuracy source. We know that even in controlled demolitions (as Chandler demonstrated) the acceleration is not equal to g, and we know that there's no mechanism to actually remove all of the mass from 8 stories.

The mass can stay, that only helps my argument. Instead of 'non-existent equivalent structure' I will now refer to it as 'almost non-existent equivalent structure'.

The reason that the collapse initiation was so quick once the penthouses had begun collapsing is that the self weight overcomes the carrying capacity of the exterior structure.

If this was the case then why wasn't the carrying capacity of the side of the structure where horizontal progression started overcome before the opposite side? Why did it have to wait for the opposite side to be ready?

You will remember that there is a 'kink' in the exterior wall, so this surely satisfies what you would be looking to see, one section of the building failing ever so slightly quicker than the rest?

That doesn't satisfy it at all. I'm looking to see one or two corners begin to fall noticeably ahead of the opposite corners. The 'kink' where the middle sags in just reminds me of a classic controlled demo. How can the middle drop before the 8 stories of almost non-existent equivalent structure on the side where horizontal progression started?

It would seem that using his own logic then that is proof that the section it was impacting was being demolished and the upper block was not demolishing it.

Due to the netting, averaging and acceleration between floors, this is the kind of difference in acceleration I would expect to see. At the next floor we then have net deceleration.

It is only when the upper block impacts more intact floors that you see the deceleration.

Like the difference between the towers initiation zone and undamaged lower structure?

We know some of the internal framing did survive, but not a gigantic amount, bear in mind that the upper section of the internal frame is still connected to the exterior, and is what is forcing its failure.

Hasn't most of the upper section of the internal fame already collapsed by the time the external frame collapses? It sounds as though the external frame was standing almost like a birdcage with only a small amount of internal structure loading it (asymmetrically).

You have? Link please?

Can't find it at the moment, I'll have another look.

I don't see anything particularly strange here? Two huge sections of building are impacting each other, and some debris and air is expelled as a result of this. I must say I don't have audio at the moment so if he's making some brilliant point I am missing it.

Watch them with audio, he explains it better than I would.

Didn't see this either, but it's hard to check without audio. Still I can think of an explanation, one piece of debris breaking into two.

What would cause a piece of debris to break into two in mid air with such force that the majority of the mass changes its trajectory by approximately 90 degrees?

reply to post by exponent

I hope I haven't missed anything, but I only just woke up so don't hate me if I did!

Actually I am glad that you replied to me as many of my previous posts have not been replied to earlier in this thread. Yeah, I know it's the weekend and I have been out with some of my friends having fun as well and I like to reply to your posts here with a clear head because I believe this to be a very important topic.

I don't know of any analysis that re-adds the energy used up damage.

Well I guess this argument is very difficult because what we see in the energy of the collapsing buildings (towers 1&2) is a mass of pulverized concrete, smoke and dust being ejected outwards and trailing behind the point of destruction. My point is that this can really go for or against either argument. It can not be proven from the videos that the top potion of the collapsing buildings, or any of the lower floors during collapse sequence, are causing or even contributing to the buildings collapse nor can it be proven that they are not. I think we should consider this as questionable either way.

I don't mind entertaining other theories, but as you noted below we need to actually get some evidence to support them.

Personally it was the interviews with the firemen of hearing explosions that sold me.

I fail to understand how all of these sounds can be explained as due only to fire and/or gravitational collapse. This is, in my opinion, very substantial evidence in favor of explosive demolitions. These eyewitnesses heard these sounds and many of these sounds were recorded as well. These sounds are signs of explosive demolitions, are they not?

many of these 'signs of explosive' are things as innocuous as air being ejected from a floor being crushed

This is simply speculation unless we can prove that "squibs" are formed from non-explosive building demolitions. I have yet to see a video comparison of squibs being made by both types of building collapse. We know that other controlled demolitions using explosives have these squibs that are caused by these explosives. This particular sign, or marker, is evidence of an explosive demolition, is it not?

the 'molten steel' which was likely other elements,

I see any explanation for this as other than burning thermite simply "grasping at straws", as it were. Here again we know that this is evidence in favor of an explosive demolition, thermite does create molten steel that looks like this, yet it remains unproven that this is from anything other than what it looks like. We know that this is not melted aluminum and the explanation that this is from batteries is simple ridiculous. So if it is not either of these then are we grasping at more straws to try and explain this away. This molten steel seen and recorded on video is evidence of explosive demolitions, is it not?

These sorts of things are explainable by both theories, but require no new information or explanation to be explained by 'damage and fire theory'.

This is where I disagree with you. I don't feel that only fire and gravitational collapse can adequately explain all of this evidence so therefore new information is needed. I would like an official investigation to look for other signs of explosive demolitions, it should not be difficult to find if it is there.

So my question is, do we or do we not have evidence in favor of the use of explosive demolitions in the collapsing of any of the three WTC towers? I would like to add that evidence 'in favor of' does not prove definitively that explosives were used. But in my opinion there is more than enough cause to at least investigate this theory.

reply to post by Devino

This is simply speculation unless we can prove that "squibs" are formed from non-explosive building demolitions. I have yet to see a video comparison of squibs being made by both types of building collapse. We know that other controlled demolitions using explosives have these squibs that are caused by these explosives. This particular sign, or marker, is evidence of an explosive demolition, is it not?

Also, if someone was going to explain these "squibs" as compressed air using the piston theory they would have to explain how the wave of compressed air was able to maintain a high enough pressure while accelerating down the building at a higher rate than the pancaking floors were.