How could WTC7 Possible have fallen like it did?

[Alchemist]

The recent NIST report admits that WTC 7 fell at free-fall speed. So you have a brick with nothing beneath it being dropped from 47th floor reaching the ground AT THE SAME TIME as a brick with 40,000 TONS of STEEL resistance beneath it...

How did a FEW pocket fires trigger this kind of free-fall structural collapse?

 

[Mick West]

It's quite complicated.

Let's say you have a long steel beam. One end is rigidly attached by multiple welded and bolted plates to a strong rigid frame. The other end rests on a shelf against a column with just a couple of bolts in place, and it's at an angle to the column. A fire below the beam makes the beam expand several inches lengthwise. The beam breaks the two bolts at one end, and falls off the shelf.

Does that sound reasonable so far?

 

[Alchemist]

Somewhat. I don't see how it relates to WTC 7 in anyway yet but go on...

 

[Mick West]

Somewhat. I don't see how it relates to WTC 7 in anyway yet but go on...

I'm asking because it's part of the official hypothesis. So I want to know if it sounds (to you) like something that might happen.

 

[Mick West]

Assuming it does. Picture a vertical steel column, one under the penthouse. It's carrying a lot of weight. Now if you removed a few floors from around this beam, then could that individual column fail by buckling?

Here's what I mean by buckling:

 

[Alchemist]

Not when these steel beams are interconnected to a network of such inner vertical core columns with the fires burning at relatively mild temperatures and isolation in comparison to fires such as those in Madrid/Chechnya.

 

[Mick West]

Not when these steel beams are interconnected to a network of such inner vertical core columns with the fires burning at relatively mild temperatures and isolation in comparison to fires such as those in Madrid/Chechnya.

But I'm asking you were to remove a few of the connections, so there's say a 50+ foot length of the column with no lateral support. Could the column fail? I'm just asking if it's possible.

 

[Alchemist]

But I'm asking you were to remove a few of the connections, so there's say a 50+ foot length of the column with no lateral support. Could the column fail? I'm just asking if it's possible.

The conditions for that to occur are VERY unlikely given the mild and isolated fires.. but even if that DID occur .. a small local failure of just one element in a NET of interconnected steel would trigger a global failure only in a movie, not in real life. They're trying to insinuate that a tiny, single initiating event can VERY EASILY lead to progressive collapse. Yeah, right...

There's something called redundancy which ENSURES that a single local failure DOES NOT LEAD to the destruction of the entire structure.

 

[Mick West]

What about multiple failures?

 

[Alchemist]

What about multiple failures?

You have 24 vertical steel core columns in the center interconnected to a network of steel beams every floor, with wall columns and other elements which are designed to share the load if there was just a compromise in the integrity of the structure. I'm not sure you realize how over-engineered this building was. Here's a full description: http://sites.google.com/site/wtc7lies/Salvarinas-1986.pdf to give you a better picture.

The conditions were IMPOSSIBLE (the fires were MILD and ISOLATED) for there to be ANY threat to the integrity of this mammoth web of steel to cause a SINGLE column failure, let alone multiple failures.

 

[Landru]

You have 24 vertical steel core columns in the center interconnected to a network of steel beams every floor, with wall columns and other elements which are designed to share the load if there was just a compromise in the integrity of the structure. I'm not sure you realize how over-engineered this building was. Here's a full description: http://sites.google.com/site/wtc7lies/Salvarinas-1986.pdf to give you a better picture.

The conditions were IMPOSSIBLE (the fires were MILD and ISOLATED) for there to be ANY threat to the integrity of this web network of steel to cause a SINGLE column failure, let alone multiple failures.

Any proof the fires were mild. The NIST report and other evidence presented on this site prove otherwise.

 

[MikeC]

The conditions were IMPOSSIBLE (the fires were MILD and ISOLATED) for ....

that is arrant nonsense if not an outright lie.

Column 79 was a CRITICAL support structure - a single point of failure.

 

[Alchemist]

Any proof the fires were mild. The NIST report and other evidence presented on this site prove otherwise.

NIST report claims that a collapse of a single unit within this web can trigger a progressive collapse which is COMPLETELY FALSE due to things like redundancy which ensures this never happens.

NIST is no different than Warren Commission claiming that a bullet was able to make turns in mid-air and cause 12 different wounds. They don't care about the facts, they have an AGENDA to uphold the official story (no matter HOW impossible it is) so the corporations can continue making more money from the war machine at your expense.

 

[Alchemist]

I live in Brookyln, NYC and I don't know ONE SINGLE PERSON who believes in the official story of WTC 7. If you're naive enough to believe that kind of a lie, you might as well believe in Santa Clauss.

 

[Soulfly]

I live in Brookyln, NYC and I don't know ONE SINGLE PERSON who believes in the official story of WTC 7.

You should get out and meet more people.

 

[Mick West]

NIST report claims that a collapse of a single unit within this web can trigger a progressive collapse which is COMPLETELY FALSE due to things like redundancy which ensures this never happens.

So that seems to be the critical disagreement here. Is this something we could discuss?

 

[MikeC]

I agree that redundancy SHOULD have coped with the failure of 1 column - but the point is that there was NOT adequate redundancy - and hence the failure of 1 column was a single point of failure - it was a design flaw.

See here for the full text of Scheuerman's analysis (1.7mb pdf)

NIST studies have shown that because of the large floor areas, the failure of just one [key] column on any one of the lower floors would cause a vertical progression of collapse so that the entire section would come down. (NIST, S.Shyam Sunder lecture) This single-column’s failure initiating progressive collapse is a design defect noncompliant with the NYC codes. The buckling of two or more of these three key columns (79, 80, and 81) would have removed support for all columns directly above, putting all upper floors in immediate longspan suspension with eventual collapse.

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[Pete Tar]

You're not sticking with the scenario Mick is trying to walk you through and are instead resorting to default rhetorical points. Just stick with the thought experiment, anything else like belief in Santa Claus, magic bullets, corporations and the war machine is irrelevant, for now.
You can understand the need for this right?

 

[Landru]

NIST report claims that a collapse of a single unit within this web can trigger a progressive collapse which is COMPLETELY FALSE due to things like redundancy which ensures this never happens.

NIST is no different than Warren Commission claiming that a bullet was able to make turns in mid-air and cause 12 different wounds. They don't care about the facts, they have an AGENDA to uphold the official story (no matter HOW impossible it is) so the corporations can continue making more money from the war machine at your expense.

Yet you provide no proof.

 

[Boston]

It's quite complicated.

Let's say you have a long steel beam. One end is rigidly attached by multiple welded and bolted plates to a strong rigid frame. The other end rests on a shelf against a column with just a couple of bolts in place, and it's at an angle to the column. A fire below the beam makes the beam expand several inches lengthwise. The beam breaks the two bolts at one end, and falls off the shelf.

Does that sound reasonable so far?

Does except you forgot the corrugated deck with about 3 inches of light weight concrete that was welded down to each and every beam, The expansion and contraction of that masonry sub-floor is about zilch, You've also got some serious uneven heating which would tend to dissipate only through individual members which were directly in contact with a heat source, so again a problem with the concept. In a nut shell, sure you can take one beam, heat it and measure just how far it expands. Off the top of my head, for steal I think its 1/8 per 8' every 100°F, so its far more likely that beam develop a bow, than snap off at the connection plate. Did NIST do any construction sample fire tests ? or did they just test using the single beam over a heat source method ?

 

[Boston]

What about multiple failures?

well they would be multiple times unlikely, so the odds of a series of unique failures gets slimmer and slimmer with each successive expectation of that exact type of failure. And there were how many columns in that building that all let go in an exactly symmetrical manor resulting in a building going straight down at free fall speed directly into its own footprint ?

 

[Mick West]

All good questions. Let's figure it out.

 

[Boston]

I guess the Architects and Engineers for 9/11 truth were able, after years and years of effort to sue whoever for a set of prints minus a few details for building 7. Rumor has it there's a major effort to analyze those prints underway now and write a report of the findings.

Baring any new evidence coming to light, fall pattern of the beams, analysis of each beams failure points, measurements of each beams deformity, stuff like that, I don't see how we can figure much out. Which is why I'm inclined to only go with the photographic evidence. Its pretty irrefutable.

I know you keep mentioning folding at the base, or buckling is another term I keep hearing, but there is no photographic evidence of such unique movements, let alone that type of failure globally. Building fell straight down is what I see without any obvious deviation of the wall structure. My personal take is there's just no explaining it with what little information there is available. We are left with, "what are the odds"? I think we know what each others answer to that one is.

Anyway I don't think there's really enough data available, and seemingly deliberately so, to really say what exactly happened.

 

[Pete Tar]

...Building fell straight down is what I see without any obvious deviation of the wall structure......

Sagging in middle, right side falls out.

Sagging, left side falls in.

 

[MikeC]

Does except you forgot the corrugated deck with about 3 inches of light weight concrete that was welded down to each and every beam, The expansion and contraction of that masonry sub-floor is about zilch,

I don't think you can weld concrete!

However you are right - concrete wouldn't expand much - but the steel has to - it cannot be otherwise - so what gives?

It is the connections that give - bolts, or welds to plates or similar.

You've also got some serious uneven heating which would tend to dissipate only through individual members which were directly in contact with a heat source, so again a problem with the concept. In a nut shell, sure you can take one beam, heat it and measure just how far it expands. Off the top of my head, for steal I think its 1/8 per 8' every 100°F, so its far more likely that beam develop a bow, than snap off at the connection plate.

That depends where the stress is concentrated and which connections are weakest - the connections holding straight or the connections at the end.

Did NIST do any construction sample fire tests ? or did they just test using the single beam over a heat source method ?

IIRC they modeled it on computer - which is completely adequate since the actual behavior of such construction elements is pretty well known.

In response to comments from the building community, NIST conducted an additional computer analysis. The goal was to see if the loss of WTC 7’s Column 79—the structural component identified as the one whose failure on 9/11 started the progressive collapse—would still have led to a complete loss of the building if fire or damage from the falling debris of the nearby WTC 1 tower were not factors. The investigation team concluded that the column’s failure under any circumstance would have initiated the destructive sequence of events.

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[Boston]

Sagging in middle, right side falls out.

Sagging, left side falls in.

The kink is a very good example of a conformity in the wall structure, I see a near perfect symmetry of collapse up until resistance from the rubble pile would normally be expected to begin to influence that fall. IE you get a pile big enough and no amount of controlled collapse can be expected to NOT fall off the pile eventually.

 

[Boston]

I don't think you can weld concrete! Obviously I menat the corrugated decking typical of high rise construction, its almost always welded down to the trusses which are in turn welded down to the beams to provide sheer strength to the floor of the structure.

However you are right - concrete wouldn't expand much - but the steel has to - it cannot be otherwise - so what gives? Well thats kinda the whole point, the concrete soaks up whopping huge amounts of heat bu doesn't deform, or at least nothing like the steel ( ) So in the end it would take some direct testing of this combination in conjunction with the corrugated material being welded to beams in order to determin exactly what "gives". Which as we all know, didn't happen. So its kinda hard to just take it on faith that the beams would dissociate from such a robust system and suddenly, all at once, spring there connections.

It is the connections that give - bolts, or welds to plates or similar.

You don't know that, we may never know that even with direct testing of similar combination's because we don't have the proper data from the rubble pile to analyze.



That depends where the stress is concentrated and which connections are weakest - the connections holding straight or the connections at the end.

It depends on a lot of stuff, so much so that without the proper data there is no really telling exactly how the building came down other than by the photographic evidence. Which to my eye represents a controlled demolition.



IIRC they modeled it on computer - which is completely adequate since the actual behavior of such construction elements is pretty well known.

None of the models I've seen even remotely match the photographic evidence

In response to comments from the building community, NIST conducted an additional computer analysis. The goal was to see if the loss of WTC 7’s Column 79—the structural component identified as the one whose failure on 9/11 started the progressive collapse—would still have led to a complete loss of the building if fire or damage from the falling debris of the nearby WTC 1 tower were not factors. The investigation team concluded that the column’s failure under any circumstance would have initiated the destructive sequence of events.

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And again, the computer analysis does not match what is seen in the photographic evidence.

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Beating a dead horse people. I just don't see much benefit in going round and round on this one again. I was just kinda pointing out that there are significant flaws in the logic

 

[Soulfly]

Beating a dead horse people. I just don't see much benefit in going round and round on this one again. I was just kinda pointing out that there are significant flaws in the logic

How ironic!

 

[Mick West]

Anyway I don't think there's really enough data available, and seemingly deliberately so, to really say what exactly happened.

No there isn't. But what we have here are competing hypotheses. There's a vague "maybe some kind of secret silent explosive, somehow", and the "progressive collapse initiated by multiple connection failures due to thermal expansion".

I've looked extensively into the evidence for and against both of these, and the second one seem to be by far the best fit.

We don't know what happened. But there's a quite plausible hypothesis.

 

[Boston]

Oh I wouldn't cause something thats a virtual impossibility a plausible hypothesis, I'd call the gubments story a classic example of agnotology, rather than a viable competing hypothesis. Unlikely in the extreme to have occurred, but the motion of the building can be easily reproduced through the mechanisms of controlled demolition.

 

[Boston]

NIST forced to admit free-fall speeds did exist at WTC 7 collapse

 

[Mick West]

Oh I wouldn't cause something thats a virtual impossibility a plausible hypothesis, I'd call the gubments story a classic example of agnotology, rather than a viable competing hypothesis. Unlikely in the extreme to have occurred, but the motion of the building can be easily reproduced through the mechanisms of controlled demolition.

Really? How did they get the penthouse to collapse, and how did they do it all silently?

And how did you work out how unlikely it was?

 

[Mick West]

NIST forced to admit free-fall speeds did exist at WTC 7 collapse

They were not forced to admit it. They simply described the motion in depth. A portion was essentially at free fall rates.

 

[Boston]

Really? How did they get the penthouse to collapse, and how did they do it all silently?

And how did you work out how unlikely it was?

If a tree falls in the woods ?

http://www.google.com/url?q=http://www.youtube.com/watch?v=CIIF6P8zBG8&sa=U&ei=tO3_UYzdHqemygGcqoD4Dg&ved=0CB4QtwIwAQ&sig2=zpymkzoC5Roz_ARp8wMMmg&usg=AFQjCNF-4Q_yTwIEeo4ON2fbCNsDsSx_jA

as for how unlikely is it for a building made up of tens of thousands of separate structural components to simultaneously fail and fall without resistance for any period of time let alone for multiple seconds, would be some multiple of the number of total components vs the chance each might shatter leaving zero resistance to the collapse of the overlying structure. There is one more factor ( OK so there's actually lots of mitigating factors ) which is the manor of failure in steel. Stuff bends, it doesn't shatter, so the chances of all exterior columns failing in perfect unison and in a manor inconsistent with the material itsenf and in the exact order to maintain sufficient continuity in the collapse such that any period of free fall speed of the entire structure at once is encountered, is virtually zero.

Thats how I estimated the odds.

 

[Alchemist]

WTC7 was a very simple steel structure and not prone to any classic progressive collapse of any kind, whatever it means.

There were 24 inner columns supported by external wall columns as per simplified figure right.

The columns are primary load carrying parts. The columns are connected by horizontal beams at every floor. The beams are secondary parts carrying local loads to the primary parts - the vertical columns. The floor panels, tertiary parts, are then hanging on the beams. There were 47 floors. Total height of structure was 147 meters.

The four horizontal beams (secondary structure) carrying the floor panels transmit average about 200 tons (50 tons each) of weight to an inner column at every floor and 50 tons of weight to a wall column. You evidently have to adjust the actual load for different spans of beams, floor areas, unusual static loads, etc.

It means that the total load transmitted to the ground by each inner column is on average 9 400 tons. A wall column transmits one quarter that load to ground or 2 350 tons. Again the real values have to be adjusted for actual values of loads transmitted to the columns from the beams.

The columns have variable dimensions from ground to roof so that the compressive stress is always <30% yield at every floor level. Evidently the bottom columns are much stronger than the top ones. The bottom column/pillar is 47X stronger than the top column below the roof! Note that the inner columns carry about 81% of the total load in this simplified model.

The maximum combined stress in any horizontal beam is also <30% yield. The dimensions of the beams (adjusted for span) are similar everywhere as they only carry local loads. The floor panels are just thin structures carrying load to the beams.In figure right we see that an inner column is removed between floors 11 and 13 adjacent to two wall columns. It is similar to Column no. 79 in WTC7.


The load carried by that inner column above floor 13 is, say, 6.800 tons and evidently the adjacent inner columns carry the same load - 6 800 tons. The adjacent wall columns carry one quarter that load - 1 700 tons.
The load - 6 800 tons - in the removed inner column is then transmitted to adjacent columns - 1 700 tons to each adjacent inner column and the adjacent wall column via the horizontal beams above the removed part.

The result is as follows:

The load in an adjacent inner column increases from 6.800 to 8.500 tons and the load in an adjacent wall column increases from 1.700 tons to 3.400 tons or the local compressive stresses increase 25/50%. As the stresses in the adjacent columns were <30% yield before removal of the column, the stresses are now still only <37.5/45% yield, i.e. well below any critical value. In reality there are more wall columns than shown in this simplified model, which are interconnected, so the load is shared between them.The bending stresses in the horizontal beams above the removed column part will double, which is still <60% yield. It means that nothing will really happens to the complete structure except that named parts become a little more stressed. There will be no vertical progression of failures due to removing one part of an inner column! To suggest, like NIST, that the whole structure collapses progressively is criminally absurd!

It can be noted that the load at ground of the inner columns carrying the extra load of the removed column increases from 9.400 to 11.100 tons or only 18%. Similar happens to the adjacent wall columns.

This effect, that you can remove a part of a structure, e.g. a piece of column, without, e.g. collapse following is called redundancy; the structure functions without that part; the part was superfluous and not really needed. The real reason for redundancy is safety; one part may get damaged for any reason and evidently the whole structure shall not collapse, if you have to modify the structure for any reason; shift the location of a column, etc.

None of the structural parts of the structure, columns and horizontal beams, will be subject to critical overload leading to any failure or buckling, when one part - a piece of column - is removed.


The report includes figures 3.10-13 showing the right side collapse below floor 16 (?) at 0.5, 2.5 (shown above), 4.5 and 6.5 seconds, while the left side remains intact. Apparently everything above Column 79 drops down due to vertical failures' progression - there are free-flying parts! But the remainder of the structure below floor 16 is just locally damaged during 6.5 seconds. Nothing drops down from below = there is no free debris there. You would then expect the upper, intact part to tilt to the right!

The horizontal failures' progression is not clear. What energy is required to produce all these failures? NIST does not provide any data.

Then there is the whole, intact, undamaged part above floor 16 - the upper intact part of WTC7 above floor 16. How to handle it?
Upper 31 Floors Part of WTC7 free fall drops for 2.25 Seconds

NIST has agreed/confirmed the finding that the upper part of WTC7, i.e. 31 floors or a 100 meters tall section, free fall drops (acceleration 9.82 m/s²) vertically with no tilting for 2.25 seconds during the collapse, i.e. there is no support/resistance of the upper part above floor 16, when it displaces downward abt 32 meters. See e.g. figure 3.15 in the report (also below)


The 'finding' is however based on measurements from a video and there is no evidence that the video is real and no scientific analysis of the origin of the videohas been made. The video could be simple Computer Generated Images, CGI, and the acceleration of the CGI roof line just copy & paste of any free fall drop on Earth. That the complete top of any wide structure free fall drops on a video is a very strong indication that the video is fake, as no such big part part of any structure cannot free fall drop, if subject to demolition from below.

What a free fall drop is, is explained here! And here!

According non-regulatory agency NIST the constant acceleration of the complete roofline is 32.196 feet/s² or 9.814 m/s² between time 1.75 and 4 seconds, when the roofline velocity increases from 11.57 to 84.01 feet/s or 3.52 to 25.61 m/s!

This acceleration of the roof line is equivalent to gravity acceleration = 100% free fall drop. The average speed during this time is 14.56 m/s and the total free fall displacement is 32.77 meters. This makes some magic controlled demolition the OFFICIAL position of NIST.

Anyone who does not understand this, simply does not understand what free fall drop means. Free fall drop means NOT DOING ANY WORK - INCLUDING DESTROYING STRUCTURE BELOW AT ALL - OTHER THAN FALLING and ACCELERATING.

It evidently means that 32.77 meters height of structure below must have been destroyed completely before the roof line starts to free fall drop. Evidently the falling WTC7 top could not destroy the WTC7 bottom as suggested by NIST.

NIST suggests that this free fall drop was initiated by failure of column 79 between floors 11/13 followed by a vertical and horizontal progression of failures (no details of course except some strange figures) below floor 16 that apparently removed all support/resistance of the upper part for 32.77 meters vertically down at one side only and the complete structure horizontally.

If WTC7 is represented by three parts A, B and C, where part A is floors 0-6, part B is floors 6-14 (24 meters tall) and part C is floors 14-47 (see picture left), free fall of part C is only possible if, e.g. part B (or more!) is suddenly and totally removed! Then part C free falls on part A.

Free fall dropping upper part C of WTC7 (above floor 14) does not apply any loads at all on the structure below floor 14 during this time!

A free falling part C does not apply any forces or loads on anything (except the air (!) it drops through) until it contacts part A! So how can the upper part C above floor 14 damage the lower part below floor 14 as suggested by NIST during these 2.25 seconds? What kind of structural analysis is done ... when no loads except air resistance are applied?

Furthermore - NIST suggests that the upper part C deforms itself during these 2.25 seconds ... when no forces (except air resistance) at all are applied to it (all masses of the upper part are in free fall drop!). Same question ... how can a free fall dropping upper part C deform?

NIST has been asked these questions ... and could not reply. Actually NIST ignored all comments made by the public.
HOW to destroy WTC 7

An explanation how the 24 inner columns below floor 14 could suddenly 'disappear' simultaneously to produce the confirmed 32.77 meters free fall of the structure above is given here. The inner columns between floors 6-13, carrying 81% of the total load, simply 'evaporated' at two locations or floor levels due to a compound applied to them that burnt extremely quickly. The load carried by the inner columns was then transmitted to the wall columns. The wall columns floors 6-13, that previously carried only 19% of the load now carry 100% of it and cannot resist and buckle inward - they are pulled in by the floor beams - as can be seen in the rubble. It explains the complete lack of parts of these lower inner columns in the rubble and also the presence of molten steel there and very strange looking pieces of junk! Further thoughts about this matter can be found here.

There are a wide number of energetic materials and components that can be used to produce the local destruction of 24 steel inner columns by simply cutting them to destroy WTC7, and the charges had to be hidden in the lower floors, e.g. floors 6 and 13. But the result could not be hidden! The upper part - floors 14-47 - would not free fall for 2.25 seconds before being destroyed later in contact with ground.

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[Mick West]

Did you read and understand all that? Maybe you could pick the question in it you think is hardest to answer, and I'll give it a go.

 

[Alchemist]

And if you TRULY want to claim that redundancy was NO FACTOR in WTC 7, here's a €1,000,000 challenge for you: http://heiwaco.tripod.com/chall.htm

Might as well make some money if you're going to attempt to prove the impossible.

 

[Alchemist]

Did you read and understand all that? Maybe you could pick the question in it you think is hardest to answer, and I'll give it a go.

The report includes figures 3.10-13 showing the right side collapse below floor 16 (?) at 0.5, 2.5 (shown above), 4.5 and 6.5 seconds, while the left side remains intact. Apparently everything above Column 79 drops down due to vertical failures' progression - there are free-flying parts. But the remainder of the structure below floor 16 is just locally damaged during 6.5 seconds. Nothing drops down from below = there is no free debris there. You would then expect the upper, intact part to tilt to the right!. The horizontal failures' progression is not clear.

What energy is required to produce all these failures?

 

[Mick West]

And if you TRULY want to claim that redundancy was NO FACTOR in WTC 7, here's a €1,000,000 challenge for you: http://heiwaco.tripod.com/chall.htm

Might as well make some money if you're going to attempt to prove the impossible.

The biggest challenge in debunking 9/11 myths is that the physics is a bit complicated, and yet the believers think they understand it. There's several concepts that are difficult to convey, but the biggest two are:

1) scale and square-cube law
2) static vs. dynamic loading

Unfortunately because it can take some time to understand these two concepts, then nonsense like in your link will always sound enticing. Although perhaps you failed to notice the writer of the page also thought that all the video and photos of the collapse were fake, and that the towers were destroyed from the bottom up, and hence is perhaps not to be taken entirely seriously?

 

[Alchemist]

I didn't scroll down or read, but you might as well take his challenge given he's that so mentally inept bases his ideas on nonsense.