A brief analysis of WTC 1 : Initial catastrophic failure.

Several of the resident truthers in this forum make a habit of asking the same question over and over, primarily in the effort to distract from the other huge holes in their pet theories of what happened on September 11, 2001. In a recently closed thread, this was the one they had fastened on:

Of course, the question assumes several facts which are not in evidence. Let's dispatch 2 of them first before looking at an analysis of the core issue.

1. The failure was not symmetrical.

As all existing videos show, both WTC towers 1 & 2 experienced tilting of the upper sections as they began their collapse. By definition, a tilt is not "symmetrical." Such a tilt can only have taken place if columns on some sides failed before columns on others did, allowing the last intact columns to act as the fulcrum around which the building section could pivot.



This failure of symmetry extended throughout the entire rest of the collapses, producing completely asymmetrical debris field. We know this from the work of professional engineers who had no interest one way or the other in either proving or disproving any particular theory of what happened that day.

The engineering firm Weidlinger Associates Inc. (WAI) was hired by the owners of the WTC to determine if the tower collapses were one or two insurable "events." If Tower 1 was toppled over by Tower 2, for example, the insurance company would pay for only one event. If the collapses were independent, however, two events would have to be covered. WAI, in their detailed analysis titled "World Trade Center - Structural Engineering Investigation," produced detailed maps of the debris distribution.

Here is the distribution map for WTC 2 which failed first:



As you can see, while there is a very rough clover leaf shape created by the fact that each of the four faces peeled off in their respective directions, there is essentially no symmetry present in the debris field. The lack of symmetry also is clearly not explainable by the presence of nearby buildings.The map shows that they had essentially no effect on the distribution. This is of course because most of the debris fell from heights above the tops of those surrounding buildings.

Here is the distribution map with WTC 1 subsequently added:



Note again... there is virtually no symmetry in the debris field, proving that there was no symmetry to the collapse of either tower.

2. The columns did not all fail simultaneously, or within milliseconds of each other.

As already noted, the initial tilt of the falling buildings prove that the supporting columns cannot have all failed at or near the same moment. Additional photographic evidence proves that the failure of the load bearing perimeter columns in the WTC towers was a gradual process that took most of an hour rather than just a few milliseconds. For example, the progressive sagging of the floor slabs (which ultimately caused at least some of the perimeter columns to fail) can be proved to have been gradually underway for more than 50 minutes.



We also know that many of the columns had been severed by the initial impact which occurred about one and two hours before collapse respectively. The truther error here seems to derive from the false belief that the initiation of the catastrophic phase of the collapses records the moment at which all the columns failed. But in fact (and as this analysis will show) that only records the point at which the proverbial last straw broke the proverbial camel's back.

The Analysis:

The WTC towers were a unique design for steel framed, highrise office buildings. It has been described as a "tube within a tube" design in which the load bearing structures were distributed across two tubes of structural steel columns. These were the inner tube consisting of 47 core columns designed to carry roughly 60% of the vertical load, and the outer tube of 240 perimeter columns designed to carry the remaining 40%. At the top of the towers was a "hat truss" which served both to help absorb the lateral loads caused by wind and earth tremors, and to redistribute vertical loads between the core and perimeter columns during periods of high lateral stress. Finally, each floor served to distribute the lateral loads along the entire height of the towers through their own complexes of steel truss work. With this as our starting point, we can calculate the designed distribution of the vertical loads (on a windless day) across every individual column as follows:

The core columns carried 60% of the load, distributed over 47 columns. This means that each of the core columns was designed to carry 1.277% of the entire vertical load of the WTC towers (60 / 47 = 1.277).

The perimeter columns carried 40% of the load, distributed over 240 columns. This means that each of the perimeter columns was designed to carry 0.167% of the entire vertical load of the WTC towers (40 / 240 = 0.167).

We also know that the designed safety margin of the WTC anticipated the normal static load to be at .6 of maximum capacity. So we can calculate the maximum (i.e. the point beyond which the columns should be expected to fail) at 1.667 X the designed loads. Thus... we can expect any individual core column to fail at 2.128% of the total load, and any individual perimeter column to fail at 0.278% of the total load. Conversely, we can expect any column to fail when it has been weakened (by damage, heat, whatever) to below 60% of its designed carrying capacity. With all of this back ground understood, let's look at the state of WTC 1 immediately after impact, but before fires could begin to affect the remaining load bearing structures.

Immediately after impact:

At 8:46:30 AM, American Airlines Flight 11 crashed at roughly 466 mph (790 km/h or 219m/s or 425 knots) into the north face of the North Tower of the World Trade Center, between floors 93 and 99. As it passed through the perimeter it severed between 31 an 36 external columns (for the sake of this analysis we will conservatively use the lower number and consider those columns that are damages to be essentially intact). A more direct impact than would later occur in the South Tower, the wreckage of the plane preceded into the core, severing at least 6 (some models give as many as 11 or 12) of the critical core columns. At this moment, the complete load bearing capacity of the tower had been reduced by at least 12.826% (31 X 0.167% for the perimeter columns, 6 X 1.277% for the core columns).

When the designed static load becomes disturbed in this manner, the hat truss is designed to redistribute the load across the remaining columns. At its most efficient, it will restore a 60-40 balance between the core and perimeter columns. The new post-impact static distribution now has the remaining perimeter columns bearing 0.192% (from the original 0.167%) of the total, and the core columns now carrying 1.465% (from the original 1.277%). This is well below the failure points of 1.667% and 2.128% respectively.

At this point the towers are wounded, but still standing.

Fires: The slow subsequent death of an engineering marvel

Now... let's consider the effect of the fires. The fires can cause any specific individual column to fail one of two ways. The most obvious is for it to heat the column itself to the point the strength of the steel is reduced to 60% and the entire safety margin is gone. This occurs at around 520 degrees Celsius (970 degrees Fahrenheit). Even the most aggressive truther efforts to downplay the effect of fire acknowledge fires of at least that intensity were burning in the WTC towers after impact. At that point the individual column will no longer be able to bear the experienced load and it will fail, usually by buckling. Its load will then be redistributed via the hat truss to the remaining structure.

The second way a column can be compromised is for the columns to be pulled out of position by floor trusses that have sagged in the heat of fires on the floors; i.e. fires that are not necessary engaging the columns themselves. Designed to distribute the lateral loads between the perimeter and core, a sagging floor would place more of its lateral strain on the lighter, thinner perimeter columns than those of the core. And of course, there is no shortage of photographic evidence of the perimeter columns bowing and eventually buckling in exactly this way on 9/11.

Either way, the failure of any specific individual column is not dependent on fire engulfing an entire floor or any other columns. Each individual column will fail or not essentially on its own during this phase between the initial impact and the eventual catastrophic collapse. But the failure of any specific individual column will always immediately result in a redistribution of the load, through the hat truss to those columns that remain. In this way, the individual failure of any single column pushes all remaining columns some distance closer to their own breaking points.

It is not actually possible to determine exactly which specific columns, and what combination of core and perimeter columns failed in the WTC Towers, or in what order. But we can still model exactly how many columns would have to fail for a catastrophic collapse to initiate. To simplify the demonstration let's look first at just the core columns (which would have been most vulnerable to direct heating), and then afterwards consider just the perimeter columns (which would have been most vulnerable to floor sagging). Keep in mind that in actuality, both were taking place at the same time.

And remember: Any value above 0.278% for the perimeter columns, or 2.128% for the core columns means that we have exceeded their load and they are now in failure.

[table="width: 800, class: grid"]
[tr]
[td][/td]
[td]Perimeter Column Load[/td]
[td]Core Column Load[/td]
[td]Remaining Core Columns[/td]
[/tr]
[tr]
[td]Baseline Loads[/td]
[td]0.192%[/td]
[td]1.465%[/td]
[td]41[/td]
[/tr]
[tr]
[td]1 Core Column Failure[/td]
[td]0.194%[/td]
[td]1.524%[/td]
[td]40[/td]
[/tr][tr]
[td]2 Core Column Failures[/td]
[td]0.197%[/td]
[td]1.586%[/td]
[td]39[/td]
[/tr][tr]
[td]3 Core Column Failures[/td]
[td]0.200%[/td]
[td]1.653%[/td]
[td]38[/td]
[/tr][tr]
[td]4 Core Column Failures[/td]
[td]0.204%[/td]
[td]1.725%[/td]
[td]37[/td]
[/tr][tr]
[td]5 Core Column Failures[/td]
[td]0.207%[/td]
[td]1.801%[/td]
[td]36[/td]
[/tr][tr]
[td]6 Core Column Failures[/td]
[td]0.210%[/td]
[td]1.884%[/td]
[td]35[/td]
[/tr][tr]
[td]7 Core Column Failures[/td]
[td]0.214%[/td]
[td]1.972%[/td]
[td]34[/td]
[/tr][tr]
[td]8 Core Column Failures[/td]
[td]0.218%[/td]
[td]2.068%[/td]
[td]33[/td]
[/tr][tr]
[td]9 Core Column Failures[/td]
[td]0.222%[/td]
[td]2.171%[/td]
[td]32[/td]
[/tr][/table]

It takes only 9 additional core columns to incrementally fail before all the remaining core columns are pushed beyond their design capacity. It may take seconds to get there, it may take minutes, it may take hours. But once it gets there, we are at the moment of catastrophic failure. When the rest of the core columns have exceeded their carrying capacity and buckled, the hat truss will immediately try to transfer 100% of the load to the perimeter columns. This is the final blow.

[table="width: 800, class: grid"]
[tr]
[td][/td]
[td]Perimeter Column Load[/td]
[td]Core Column Load[/td]
[td]Remaining Core Columns[/td]
[/tr]
[tr]
[td]Complete Core Failure[/td]
[td]0.766%[/td]
[td][/td]
[td]0[/td]
[/tr][/table]

The failure of the core immediately leads to the failure of the remaining perimeter columns. At this point there is nothing left to hold the upper section of the WTC Tower up, and total catastrophic collapse is underway. The failures did not all occur "in milliseconds." Only nine additional columns (out of 41) had to be exposed to any fire at all. And still... a point of catastrophic failure is reached at which all the remaining elements are overwhelmed, and complete collapse begins in a moment.

We can perform the same analysis for the perimeter columns instead of the core columns. Again, keeping it simple and only considering perimeter failures, and leaving out some of the interim steps just to save bandwidth, the results look like this.

[table="width: 800, class: grid"]
[tr]
[td][/td]
[td]Perimeter Column Load[/td]
[td]Core Column Load[/td]
[td]Remaining Perimeter Columns[/td]
[/tr]
[tr]
[td]Baseline Loads[/td]
[td]0.192%[/td]
[td]1.465%[/td]
[td]209[/td]
[/tr][tr]
[td]1 Perimeter Column Failure[/td]
[td]0.193%[/td]
[td]1.468%[/td]
[td]208[/td]
[/tr][tr]
[td]2 Perimeter Column Failures[/td]
[td]0.194%[/td]
[td]1.471%[/td]
[td]207[/td]
[/tr][tr]
[td]3 Perimeter Column Failures[/td]
[td]0.196%[/td]
[td]1.474%[/td]
[td]206[/td]
[/tr][tr]
[td]43 interim failures[/td]
[/tr][tr]
[td]47 Perimeter Column Failures[/td]
[td]0.274%[/td]
[td]1.622%[/td]
[td]162[/td]
[/tr][tr]
[td]48 Perimeter Column Failures[/td]
[td]0.276%[/td]
[td]1.626%[/td]
[td]161[/td]
[/tr][tr]
[td]49 Perimeter Column Failures[/td]
[td]0.278%[/td]
[td]1.630%[/td]
[td]161[/td]
[/tr][/table]

At the 49th individual perimeter column failure, all the remaining perimeter columns have been pushed to their failure point. In the reverse of what we saw in the core column analysis, the hat truss then attempts to transfer 100% of the vertical load to the core columns, which then in turn are driven to catastrophic failure.

[table="width: 800, class: grid"]
[tr]
[td][/td]
[td]Perimeter Column Load[/td]
[td]Core Column Load[/td]
[td]Remaining Perimeter Columns[/td]
[/tr]
[tr]
[td]Complete Perimeter Failure[/td]
[td][/td]
[td]3.415%[/td]
[td]0[/td]
[/tr][/table]

The failure of the perimeter immediately leads to the failure of the remaining core columns. At this point, again, there is nothing left to hold the upper section of the WTC Tower up, and total catastrophic collapse is underway. And again, The failures did not all occur "in milliseconds." Only 49 additional columns (out of 209) had to buckle as the result of floor sag. This does not even require all the columns on a single side, even though the way the WTC was constructed they would all tend to fail as a unit.

But still... a point of catastrophic failure is reached at which all the remaining elements are overwhelmed, and complete collapse begins in a moment.

Summary:

The collapse of the WTC Towers was not symmetrical, and the model shows there was no expectation that it be so. The truther claim to that effect is a fabrication with neither evidence nor reason behind it, and is contradicted by both the video evidence from that day as well as the physics involved.

The columns of the WTC Towers did not fail "in milliseconds." The model shows that there is no timing requirement whatsoever for such a catastrophic failure to take place. It could have taken minutes, it could have taken hours. It actually took 56 minutes for the South Tower, and 1 hour, 42 minutes for the North.

And the total failure of the Towers does not require fires to range uniformly "across a 200 x 200 ft building." Only 9 core columns (roughly one out of five) or 49 perimeter columns (roughly one out of four), or some equally limited combination needed to be affected by fire or by floor sag for the entire structure to be driven past the point of failure.

 

Outstanding post!

 

what a load of crap.

in "DEMOLITION" terms it was symmetrical.

this is more of your goal post moving.

changing the definition from its common usage in "DEMOLITION" terms meaning to obtain a symmetrical straight down collapse to your crazy idea of a perfect geometric symmetry is intellectually dishonest and not deserving recognition.

The top of the building tipping does not mean it was not a symmetrical demolition as can be seen here;

​

so you wasted a lot of text when you come out here on a false premise.

That and I already showed you what is takes to bring the tower down and it no where near approached that.

​

worse and even laughable is the idea that a floor that could not even hold itself up had the strength to pull in the sides.

So a red hot floor that is weak and sagging has the strength to pull in the exo.

Listen to yourselves, that is pure lunacy.

Its difficult to contain myself I laugh so hard when you people push that fire/heat weakened floor pulling in the sides crap "as a result of heating and sagging" Its (*)(*)(*)(*)ing impossible. It cant even sustain its own weight! LMFAO

Now if you want to blow the core columns so they are hanging and the floors are holding up the weight of the core instead of the core holding up the floor, then hell yeh it will pull in the sides.

​

as you can see there is literally no overloading what so ever of the connector when the floor sags.


All you have is a huge load of bunk buried in generalities as always, its the official story hugger SOP.

 

Your opinion is noted. Your task remains to actually demonstrate it.

It is not clear that you have any command whatsoever of the demolition lexicon. Perhaps the single professional community that has been most unified in their complete rejection of the "controlled demolition" hypothesis are the actual experts in controlled demolition. And primary among their criteria for rejection is lack of anything even vaguely resembling symmetry in the collapses. By every definition, and by any profession's terms there was nothing symmetrical about the collapse of the WTC towers. Not its inception, not its progression, and not its aftermath.

How can I have moved a goalpost when I have not even set for you a goal? I have provided an analysis and critique, nothing more.

It is fascinating to see that you almost come right out and admit that you are equivocating. It is one of the greatest sins of conspiracy theorists (of any stripe; truthers, birthers, chemtrailers, creationists) that they hedge their arguments with ambiguous language specifically so that when they are caught in an error they can respond with, "that's not what I meant." Of course, it doesn't help you this time that your usage of "symmetrical" is not a demolition industry usage at all. It is truther jargon, not demolitions jargon. Here (for contrast) is what the discussion of a genuine demolitions expert sounds like:

Note that real demolitions experts do not even discuss "symmetry." Technical jargon is a tool that professionals use within their fields to insure clarity of communication and understanding between themselves. The truther use of the word "symmetry" serves an opposite purpose; to obfuscate meaning and communication for the purpose of enabling subsequent prevarication.

So as we see from Brent Blanchard's account, not only is there no apparent "demolitions" use of the word at a time when it would have been expected were it actual demolitions jargon, but the demolitions experts assert that your own description of the event is egregiously false.

There was nothing "symmetrical" about the WTC tower collapses. Not their inception, not their progression, and not their aftermath.

Of course it does. The brief video you show here in which the top of the building begins to tip is also not symmetrical. And you seem to have conveniently edited out the rest of the video which would tell us how the collapse progressed and the debris ultimately fell. It frankly appears (in the tiny, completely out of context clip you shared) to be the initiation of a botched demolition. I am uncertain how you imagine that clip helps your argument.

Do you not know what a "premise" is either? You have demonstrated no "false premise." You have not even demonstrated the capacity to tell the difference between a premise and a conclusion. You have merely tried to redefine your way out of the prosaic observation that your claims are objectively false.

I don't even know what you are trying to say there. Hanging out a random declaratory sentence is not an argument. You have already "shown us" many things, few of which you yourself understand or can describe honestly. In contrast, I have (twice now) gone into detail and shown you my math. In both cases, you have desperately tried to change the subject rather than respond to the demonstration.

Yet another assertion dependent entirely on the technical and factual ignorance of the person making it.

The floors in the WTC did not "hold themselves up" at all. They were designed to transfer lateral loads, not vertical loads. They were "held up" by the vertical load bearing "tube within a tube" structures. Pulling and/or pushing against the perimeter and core columns was the very thing the floor truss system was created to accomplish. Of course the design did not account for the sort of unimaginable events that occurred on 9/11.

That they "had the strength to pull in the sides" is proven by the photographic evidence of the towers themselves taken on 9/11 during the period between impact and collapse. This is not theoretical. This is not hypothetical. This is an empirical observation of incontrovertible fact.

Once again... we can see from the photographic evidence of the day that this is exactly what did happen. But since you are again depending on your own technical and factual ignorance to frame your objection, your conceptual understanding of the process is tenuous.

The structural insult of the sagging floors does not come from the "strength" of the floors, but from the weight of the floors and the changing vector components of their load on the perimeter columns. When the floors are rigid and intact, the vector of their perimeter load is straight down. When the floors are sagging that vector shifts from strictly vertical to an acute angle downwards and inwards. As long as the floor does not actually break apart, progressive sagging continues to change the direction of that angle putting more and more lateral strain (of a sort they were not designed to withstand) on the perimeter columns.

And again, as we see from the actual evidence, the results were a progressive bowing of the perimeter columns, and their eventual complete buckling inwards. This is not theoretical. This is not hypothetical. This is an empirical observation of incontrovertible fact.

Last I looked, accusations of lunacy were not considered actual responses to a technical argument.

Show your math and prove the lunacy. Or don't. That's up to you.

The problem with your alternative theory here is that the bowing of the perimeter columns shows up very early in the photographic evidence of the WTC,preceding the catastrophic failure of the building by many tens of minutes. Blowing the core columns would (as we can see from the analysis I provided) have resulted in the immediate inception of collapse. There is no sane way to associate effects with a cause when they are proved by the photographic evidence to have preceded what you claim must have caused them.

It is a basic law of nature; causes must precede their effects. The effects can't come first.

That has nothing whatsoever to do with the discussion in progress here. Nothing in my analysis requires or depends on anything having to do with the truss connectors beyond that they remain intact. And the NIST images you show clearly demonstrate that they remained intact.

And you end your objection the same way you usually do; immersed in a deep sea of delicious irony.

Again, any reader can see the difference between "generalities" and having demonstrated in detail the actual math involved.

Thank you for proving again that you simply do not have even the most simple understanding of the physics or engineering necessary to comment intelligently on what happened to the WTC towers.

You made a challenge. It has been met.

 

Yes it has never been seen before

http://en.wikipedia.org/wiki/Rail_stressing

 

a sagging floor due to "weakening" does not expand beyond its boundaries and contrary to your example the forces remain and continue to pull toward the center, more misapplication from you people.

just another debunker red herring

 

what happens if the sagging floors break away from the exterior columns?

 

they cant pull in the exoskeleton

you will soon discover that you are victims of your own trappings ;

 

video and photo evidence shows they did infact pull in the exterior columns.

 

My examples are from real life. Are you arguing that steel does not expand under heat?

 

the core doesn't need to be blown (with a Jewish star) for the sagging floors to pull the exterior walls inward.

 

AGAIN:



well if you cannot do our own work you have to believe someone dont you! LOL

steel stretches under load when it gets hot. the whole argument debunkers and nist uses is bogus! LMAO

 

Before I respond, let me note again that Koko remains too terrified to address the core of the OP. Instead he continues to persevorate over trivial red herring like "symmetry." It does not suggest that he understands any of the actual discussion taking place in this thread.

There does not exist any definition of "symmetry" in any profession (technical or otherwise) to which your egregious misuse of the term can justifiably correspond. Whatever your actual intended point might be, your use of the term is only a demonstration of your inability to clearly communicate it.

There is nothing in the WTC collapses that displays "symmetry" in any sense whatsoever. Not in a metaphorical sense. Not in a casual sense. Not in a colloquial sense. And absolutely not in any technical sense. Why you find it so important that you desperately wish to keep using it is beyond me. It only makes you look confused and clueless, and in return helps your argument not one whit.

I can find no example of any demolition person using the term, period. Let alone using it to mean anything close to the way you insist on misusing it.

It is ironic that you try here to accuse me of a "cut and paste litany" when it is clear that you have no idea what the NIST excerpts you cut and pasted even mean. They have nothing whatsoever to do with the issues under discussion, with the analysis that I offered in the OP, or the answer to your challenge which has been fully met. You may as well have posted a recipe for beef stew.

If you had any background whatsoever in physics or engineering you would never had offered that as a response in the first place.

There is neither an answer, nor a question, nor one in the form of the other anywhere in that bald assertion.

It is indisputable fact that significant bowing of the perimeter columns did occur. It is an indisputable fact that the bowing took place only on those floors where fires were underway. It is an indisputable fact that the floors were sagging as a result of the fires. It is an indisputable fact that this bowing was gradual, progressive, and preceded the catastrophic collapse of the buildings by more than a half hour. All of this is clearly proved by the photographic evidence of the WTC towers on that day.

It is also an indisputable fact that the only structures in the WTC towers that can have caused that bowing are the floor trusses. Even you admit this fact when you offer (as you do again below) the insane and time violating suggestion that it was preceded by the "blowing of the core."

So we are not talking hypothetically. We are not talking theoretically. We are not talking about the results of some tendentious computer model. These are empirical, objective facts.

As a final aside, you insist it is absurd to believe that "steel weakened to the point of failure can somehow magically pull in the sides when overloaded nonweakened steel cannot." Who ever suggested that "overloaded nonweakened steel cannot?"

See? Now that's a "straw man."

Yes it is. As I recall, you are the only one of us in any thread that has ever actually declared that heat makes steel stronger. At this point you are arguing only with yourself.

That is a child's line drawing. And as we have already established, the scenario it describes is disproved by the objective evidence of that day. Since the bowing of the perimeter columns preceded the collapse by several tens of minutes, they cannot have been caused by the blowing of the core. For as my analysis proved, the loss of the core would result in immediate catastrophic collapse... not a gradual collapse lasting the better part of an additional hour.

Your ad hoc theory is a direct violation of both the law of causality as well as time's arrow. Time does not go backwards.

This is not a concept that should have been difficult for you to grasp. How is it that you can't seem to get a handle on it even after several posts?

 

And then you posted this animated GIF:

http://i1273.photobucket.com/albums/y410/mypbemotes/wtc physics/sid1_zpsf09d7aff.gif

Which shows the floor trusses pulling the outer columns inward. So which is it, are the trusses strong enough, or are they not strong enough?

 

Besides the weight of the floor pans themselves and the concrete flooring poured into them,wouldn't the thousands of pounds of furnishing,office equipment, etcetera add to the sag of the floor pans?

Say point A was the connection at the core columns, and point B was the connection at the perimiter walls,and point c is between the two..wouldn't all that extra weight at point C cause it pull away from the perimiter columns?

 

heat causes steel to weaken and expand.

that would cause the floors to sag and pull the exterior walls inward.

like we saw on 9-11

 

It is still a valid question. After the initial 10 stories collapsed onto the lower 90 why did the lower portion of the building collapse so quickly? There were no fires in the lower sections weakening the structural columns. The columns in the lower portion would be pushing back and decelerating the collapse not allowing it accelerate unless they were taken out within milliseconds of each other.

Only the top 10 floors, or so, are wounded. The rest of the building is just fine at this point. Every column below is undamaged. At 28 seconds we observe the antenna still in a vertical position. The collapse begins at 29 seconds about 6 floors from the top and the antenna begins to tilt as the top portion begins to drop. At 30 seconds we observe fiery explosions around the tenth floor from the top. How do you explain those explosions?

[video=youtube;sYzIja6mlRs]https://www.youtube.com/watch?v=sYzIja6mlRs[/video]
https://www.youtube.com/watch?v=sYzIja6mlRs

I don't agree that a total catastrophic collapse is underway at this point. A partial collapse of the top ten stories was underway. Newton's third law of motion states that the structural columns in the 90 stories below the collapse would push back and resist the collapse causing deceleration unless all their load bearing columns were suffering global symmetrical failure within milliseconds of each other too.

 

However it has to be remembered how the floors were constructed they each independently carried their own load of 5000 tons. So when the upper 10 floors began to move, the next intact floor is trying to sustain 50,000 tons of load. Well beyond it design capacity.

 

air being pushed down into the fires.

 

the only thing that is clear is that you are working very diligently to write bogus definitions and proffer bogus understanding of both the words and physics itself.

there is no single way to demolish any one building. you can take out one column at a time if you want till critical mass is reached then blow the rest. your insistence that there is only one way of that the use of the term symmetry has narrower boundaries that I deescribed is just more of the same stramanning and and milliseconds also translate into seconds. Your extreme desire to use frivolous arguments as a basis to prove the official story hugger version is ludicrous.

so here we have symmetrical demolition it comes straight down




so here we have a muffled symmetrical demolition it comes straight down



so here we have a sectional symmetrical demolition it comes straight down in sections



so here we have symmetrical demolition it comes straight down



so here we have NON symmetrical demolition where one side is blown, the remaining supporting structure is not blown and is a guide to direct and force it to tip over in the prescribed predetermined direction. Really basic stuff people.



you claim to be some kind of an engineer with authority to debate the matter, why do I have to continually correct you.

 

wrong...the top '10 stories were intact for much of the initial collapse,no matter how much they 'pushed back' the inertia from the top floors pushed them past their design limit

 

Which would demonstrate obvious deceleration not acceleration.

- - - Updated - - -

The lower 90 would push back and decelerate the collapse not let it accelerate.

 

Why just on that one floor?

 

Why?

The upper part was getting heavier as the collapse progressed..why would it decelerate?

 

Newton's third law of motion.