The Uniqueness of the WTC7 Collapse

Boston

Active Member

you mean kinda like bldg 7 was not symmetrically constructed ? or that it didn't fall symmetrically and so represents what happens when a random asymmetrical failure occurs "down low" which was my point.

If you require another example see above, which by the way, wouldn't paste bellow which is where I was aiming for, I finally gave up and just pasted it wherever it would paste.
 

Boston

Active Member
Don't dismiss the report if you won't read it.

If you send someone an 800 page report, supposedly in support of a particular claim, its a bit unreasonable to expect them to search the entire thing for one little tidbit. I'm ten pages into the 30 ish page suggested area and I've so far seen nothing that is discussing the buildings assumed sway before the collapse
 

Boston

Active Member
That was also a concrete reinforced building, not a steel frame one. Have you looked at the condition of that side of the building before it fell over? It was a badly down controlled demolition job.

Check out this link.

http://www.structuremag.org/Archives/2007-11/SF-WTC7-Gilsanz-Nov07.pdf
actually that wasn't a controlled demolition at all, it was an apartment building that just fell over on its own, but it did so due to a random failure, "down low" which for a second time shows that a random asymmetrical failure "down low" doesn't result in the instantaneous failure of every column resulting in a symmetrical collapse. It instead results in the building falling over.
 

Mick West

Administrator
Staff member
I'll grant you any day that fire will weaken steel, but I'll also point out that when weakened steel doesn't fracture, it bends, particularly when placed under load. Vertical columns tend to move inward towards the fire, depending on there load characteristics, same with horizontal beams, they also tend to react by bending towards the point of heat. On the other hand, how much heat does it take to cause a catastrophic failure to every column, simultaneously, particularly when that heat is not applied uniformly ?

I'd also reiterate that asymmetrical weakening of the steal, is not likely to result in a global symmetrical collapse exactly synonymous with what I'd see in a controlled demolition where the vertical columns have a section removed mechanically from the base to release the kinetic energy necessary to sustain a collapse into itself and overcome "itself" being the path of greatest resistance. IE fall in instead of over.


It was not a symmetric collapse. The exterior eventually fell all at the same speed, but it took a lot of asymmetric failure to get to that point.

I encourage you to keep reading NCSTAR 1-9, it's an interesting paper. Let me know if there's a particular bit you are looking for in it.
 

Boston

Active Member
awesome, lets me past to the top of the page but not the bottom. Crazy. Must be Gremlins

It would take months to really do it justice.

I wasn't looking for anything in it other than you suggested I read a certain section which I at least thought you had suggested supported your claims of the motion of the building having been fully analyzed. I see nothing of the sort within the area suggested.

Sooooo what was asymmetrical about the collapse ? I'll agree that the fires and damage to the building were asymmetrical in nature, I'll also agree that the roof structures fell in a progressive manor, but from there, its a very symmetrical failure. All four corners and the two points of the kink all exhibit beautiful symmetry. The four corners all fell at roughly free fall speed, and in unison with each other as well as the kink itself. There was also some really nice linear symmetry between the points of the kink and the corners as well as between the short sides of the building and the long. I'm not sure what it takes to qualify as a symmetrical failure but given the variables involved I just don't see how anyone could ask for a more perfectly symmetrical failure.
 

Mick West

Administrator
Staff member
awesome, lets me past to the top of the page but not the bottom. Crazy. Must be Gremlins

It would take months to really do it justice.

I wasn't looking for anything in it other than you suggested I read a certain section which I at least thought you had suggested supported your claims of the motion of the building having been fully analyzed. I see nothing of the sort within the area suggested.

Sooooo what was asymmetrical about the collapse ? I'll agree that the fires and damage to the building were asymmetrical in nature, I'll also agree that the roof structures fell in a progressive manor, but from there, its a very symmetrical failure. All four corners and the two points of the kink all exhibit beautiful symmetry. The four corners all fell at roughly free fall speed, and in unison with each other as well as the kink itself. There was also some really nice linear symmetry between the points of the kink and the corners as well as between the short sides of the building and the long. I'm not sure what it takes to qualify as a symmetrical failure but given the variables involved I just don't see how anyone could ask for a more perfectly symmetrical failure.


The internal collapse was asymmetric, as demonstrated by the order of the penthouse collapses.

The exterior fell at the same speed once it had started to collapse because of its rigidity. The exterior of the building was a very strong frame with rigid connection. Perhaps you'd care to explain how the downward motion of the four corners could possibly not be at the same speed?

There's a perfectly reasonably hypothesis here as to how it fell that seems to meet all the facts. The "symmetrical" fall (that you find so incredible) is part of that hypothesis. It's not something that disproves the hypothesis, it's a crucial part of it.

Have a look at this:
 

Cairenn

Senior Member.
Wow, reading a paper is a problem, but we are supposed to watch long You Tubes. A peer reviewed paper full of FACTS and science instead of a You Tube of someone's opinion.
actually that wasn't a controlled demolition at all, it was an apartment building that just fell over on its own, but it did so due to a random failure, "down low" which for a second time shows that a random asymmetrical failure "down low" doesn't result in the instantaneous failure of every column resulting in a symmetrical collapse. It instead results in the building falling over.

Then please explain why there is a HUGE HOLE in the building before it collapsed? The second link shows the hole clearly.

http://freshome.com/2009/08/02/turkey-building-demolition-and-an-amazing-unexpected-bad-surprise/

http://www.dailymail.co.uk/news/art...rong-building-fell-tumbled-like-matchbox.html


http://news.bbc.co.uk/2/hi/8179857.stm
 

Boston

Active Member
your getting the 2 video's mixed up and yah an 800 page PDF is a bit much for my afternoon. I'll be happy to reference a page within the PDF but reading through the whole thing "just for fun" isn't my idea of a day off.

again we don't know there was an interior collapse. NIST is guessing as to its occurrence because it can't find any other solution to how the building fell, except I question whether or not they looked at the controlled demolitions possibility, does anyone have definitive of there having considered this possibility ?

we do know there was an asymmetrical collapse of the penthouse mechanical structures on the roof.

The more rigid the exterior is than the interior, the more rigidity it imparts to the structure as a whole. Remove that part of the structure the exterior is supporting, and it becomes more stable, not less.

Not only that but an asymmetrical pattern of damage focused at the bottom of this exterior frame assuming that frame was significantly stronger than it needed to be due to its expectation of imparting rigidity to the interior of the building would result in it simply falling over rather than imploding. Its kinda like that concrete building simply rolling down the hill once one side blew and the other didn't

Sorry guys but your just kinda shooting yourself in the foot with each attempt. The Nist video is pure conjecture, may we please have the blue prints and structural analysis so we might confirm the connections strength which lead to this hypothesis, we'd also need a detailed review of the steal substructure and a detailed review of the known damage applied to that analysis. In a nut shell there is no way to corroborate this hypothesis.

It has no more likelihood and actually IMHO significantly less likelihood than does the controlled demolition hypothesis

I do see some progress tho Mick, you seem to have moved into the camp that at least the part of the building that we can see collapse, minus the penthouse structure, did collapse in a symmetrical manor

oh and that video animation does not mimic what we see in the film evidence, there is innumerable pieces of debris shedding from the exterior of the animated building that we don't see in the film evidence. I earlier posted that I would have expected this in a collapse scenario of the type NIST is suggesting, yet this is not what we see when we observe the actual collapse
 

Boston

Active Member
OK I read the suggested 30 or so pages starting about 260 and going to about 290, there was nothing concerning the motion we were discussing at the time it was suggested I read that section of the report. I'm going to assume that no actual evidence exists that might define this motion in such a manor as we might conclude much of anything from its possible existence. Although I'm always open to new information.

What I did read was an rather long and drawn out description of the fires as they moved through the building, I read nothing that indicated all four corners of the building were on fire at any given time or that would lead me to believe there was any area of this building that was subjected to fire for more than about an hour and a half. Once the fire moved on, the steal begins to cool and gains back at least a portion of its strength. Significant portion actually, depending on how it was cooled.

I'm again surprised that what amounts to obvious asymmetrical fire damage of the same type experienced by countless steal framed structures is being forwarded as a primary cause of what is clearly a symmetrical collapse. If I recall there is even a line in this report that admits this explanation has an extremely low probability

Question, how many of you would consider a controlled demolition a form of symmetrical collapse
 

Cairenn

Senior Member.
Do you now agree that the Turkish building was a failed controlled demolition?

It was built in the 1920s, with a very different type of construction.

Do you agree that out of control fires can cause the deformation of long steel beams and the collapse of whatever is on top of those steel beams?

I still do not consider any of the WTC buildings as a symmetrical collapse. None of them where.
 

Mick West

Administrator
Staff member
OK I read the suggested 30 or so pages starting about 260 and going to about 290, there was nothing concerning the motion we were discussing at the time it was suggested I read that section of the report. I'm going to assume that no actual evidence exists that might define this motion in such a manor as we might conclude much of anything from its possible existence. Although I'm always open to new information.


I think you might have been reading the PDF page numbers, not the actual page numbers. I was referring to section 5.7, starting on page 261, which is page 305 of the pdf.
 

Boston

Active Member
cairenn, I'm sorry but you are completely confused.

Mick I think I did exactly that, its late tho and the girl is kinda staring at me like "get the hell off your computer" so I think other than commercial interruptions, I'm going to have to eat some pop corn, drink this beer, and at least try and pay attention to whatever movie we are watching. ;-)

have a great night people, its been fun.
 

Mick West

Administrator
Staff member
You mentioned glass earlier, that section mentions something similar:

Note that section 5.7 only gives an overview of all the video analysis, there's much more technical detail of the pre-collapse analysis in Appendix C (page 679, or 745 in pdf pages)
 

jomper

Inactive Member
It would need to be self supporting until it collapsed. Once it has started to collapse it is no longer self supporting.

Like if you take a tape measure, extend it vertically, it's self supporting until it start to collapse (usually around about ten feet of extension, but the more you can do, the more accurate the analogy. Once the tape measure starts to collapse, then it becomes a floppy noodle.

Or look at the can


It's supporting several thousand times its own weight! (14 grams supporting over 60,000 grams). Yet it's just super thin flexible aluminum. When it starts to collapse it's a floppy noodle.

You can't really have a fully accurate physical analogy here because of scale. But these things are still illustrative of the general principles.
The general principle of gravity acting on a structure is not similar to a man standing on a can. Neither does a self-supporting structure turn into the equivalent of a wet noodle by losing all strength throughout the structure if the conditions for collapse initiation occur.

This must be obvious to you.
 
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Cairenn

Senior Member.
Jomper what is your opinion of this link? It is only 4 pages long.

http://www.structuremag.org/Archives/2007-11/SF-WTC7-Gilsanz-Nov07.pdf


 

Boston

Active Member
Mick, good point, I'll definitely be looking into that one. As I mentioned any significant failure of the interior structure should have sent some kinda of deformation throughout the exterior structure significant enough to be observed. The glass surface and its reflective properties would be a very good indicator of that deformation, should it in fact exist.

My argument kinda hinges on the video evidence so I'd be compelled to admit some force acting on the building which is evident, assuming a review of the film actually shows a "ripple" consistent with the interior collapse hypothesis. Is the video in the PDF or do you have a copy of it ?

Cairenn

point 2 in your previous, is pure conjecture, what fires there were, are small, and moved within a small relatively restricted area of the building ( I just got done reading 30 pages of crap on fire actually ) no evidence of a fuel fed fire exists and the likely temp of this fire was no greater than any other office fire. Nor was there any specific area that burned for more than a few hours at most, many burned for significantly shorter times. Steal as we all know by now both heats and cools over time. So after many hours of cooling the steal will regain much of its compromised strength, however any statement beyond that concerning building 7 is as much conjecture as is this one your quoting

point 3 in your previous is also pure conjecture, the failure of the penthouse structures is evidence of a failure of the penthouse structures, beyond that its all assumptions and guess work.

point 4 wrong, a beautifully symmetrical global collapse is exactly what resulted from whatever forces were acting on the building at the time. What those forces where and exactly how they resulted in a global collapse exactly synonymous with a controlled demolition is unknown. But it is unlikely in the extreme that asymmetrical damage and asymmetrical minor fires would result in a symmetrical collapse.
 

jomper

Inactive Member
The operative word would be hypothesis. Random damage and fire cannot be expected to reproduce conditions for a collapse that resembles a controlled demolition, even if the similarity is literally superficial; such an extraordinary conclusion could only be supported not only by the examination and analysis of an extraordinary amount of physical evidence from the building -- including mapping of the debris field against the blueprints as Boston says -- but also the exhaustive investigation and elimination of alternative hypotheses irrespective of counterindicating factors such as the supposed absence of explosions on video records (an absurd argument to make in the first instance).

1: Yes, but bear in mind NIST concluded the damage from debris was not a major factor in the structure's collapse. This is surely partly because even NIST found it hard to argue that asymmetrical damage would result in a near-symmetrical collapse event
2: Supposition, isn't it? However, if it was the case, exactly why the building did not collapse towards the East side would have to be explained
3: See 2
4: I hope this isn't referring to the NIST model, which as we know was built in a computer environment to support a hypothesis which cannot be verified and is in any case a poor representation of the evidence in its failure to reproduce the key elements of symmetry that only pedants on boards such as this one could suggest are not there
 

Cairenn

Senior Member.
Those were statements from the Struture magazine, not from me.

http://www.asce.org/sei/Content.aspx?id=23622324310



STRUCTURE magazine is a joint publication of SEI, the Council of American Structural Engineers (CASE), and the National Council of Structural Engineering Associations (NCSEA), and serves as the combined, primary communication vehicle for the three organizations

SEI is the Structural Engineering Institute


These are EXPERTS in buildings and you just dismissed their findings as of no importance.

Once steel loses it's strength it does NOT get it all back. There is a long thread here where that is discussed. Steel is persnickety material. It's toughness, and strength and brittleness is all dependent on temperature and how it cools after getting hot.
 

Cairenn

Senior Member.
It was not an argument from authority, since it was from authorities in the field and it was a consensus.

Folks spend years in becoming experts in a field, be it structural engineering, or medicine or even in sport. To then chose to ignore their assessments of something, because it doesn't agree with your non expert opinion is foolish to me.


Argument from authority (argumentum ad auctoritatem), also authoritative argument and appeal to authority, is an inductive reasoning argument that often takes the form of a statistical syllogism.[1] Although certain classes of argument from authority can constitute strong inductive arguments, the appeal to authority is often applied fallaciously.
Fallacious examples of using the appeal include:
  • cases where the authority is not a subject-matter expert
  • cases where there is no consensus among experts in the subject matter
 

jomper

Inactive Member
If there was consensus people like Ronald Brookman would not be filing FOIA requests in an entirely understandable desire to verify the NIST model. You asked for my response to your post, which I have given; now you are appealing to the authority of its source instead of addressing the points made.
 

Mick West

Administrator
Staff member
The general principle of gravity acting on a structure is not similar to a man standing on a can.

The principal is exactly the same. The vertical members (the columns in the building, or the sides of the can) transfer the load down to the ground. The stability of the structure is maintained by the rigidity of the exterior of the structure.

There are significant differences of course. The most significant are those due to scale. The can is much stronger than WTC7. It can support thousands of times its own weight. WTC7 would have difficulty even stacking one more WTC7 on top of it. WTC7 on the other hand had much greater stability, due to it internal structure, which the can is lacking. If the can had a similar internal structure, then it would require much more than a light touch to make it collapse.

Neither does a self-supporting structure turn into the equivalent of a wet noodle by losing all strength throughout the structure if the conditions for collapse initiation occur.


When is a steel column like wet noodle? When it buckles.

A column can support a lot of weight when it's vertical. But only a tiny fraction of that weight when it is not longer vertical - when it's bent away from the vertical plane. Just like the can, the vertical walls of the can transfer the load perfectly, but as soon as they are out of line, then it's wet noodle time.

Remember what the NIST hypothesis is here:

A) The interior collapses asymmetrically, leaving the exterior
B) The exterior, lacking support, collapses like a can being crushed.

It's not like the entire building with all the interior columns collapses all at the same time.

Back to the can. Imagine you were to give it some internal support by filling it with water before standing on it. You then turn it upside down and stand on it. The water will drain out, and then the can will collapse. This simulates the collapse order to wtc7.

The building seems to collapse symmetrically for the reasons NIST gave. The exterior is stronger than the interior.
 

Boston

Active Member
The NIST model IMHO does not represent what I see in the film evidence. Oh and this business about "experts". I might have mentioned that I literally grew up crawling around steal superstructures on buildings like Mass Eye and Ear hospital when I was a kid. One of my first jobs was on high rises as an assistant super, I worked my way through college building the craziest stuff I could find to build ( pays better ) and throughout much of my earlier career I maintained my A class contractors license. ( hey it got me through some rough times )

I've tried to stick to the sciences, which is what I went to school for, but we can't always do what we really want to do in life, so I always had something to fall back on with my skills as a builder.

In the end, I laugh at many of the Experts who've never once stepped out of the orifice long enough to actually know what they are doing. Most only visit the job site long enough to get there pictures taken with the prints and a hard hat and then skip out to lunch.

I can't tell you how many times the architects or engineers write ( all measurements and dimensions to be field verified ) on the prints. IE, they really don't know if any of there scribbling actually works or not. IMHO the only experts are the guys who actually bolt the steal together, and thank all the gods I'm not one of them. Its a rough job and I've mad respect for those guys.

That in mind, I about fell out of my chair when I saw some of the materials testing parameters used in estimating the strength of steal when subjected to fire. Sorry but a simple beam, unsupported at its ends, stacked with its approved loading, and a gas fed fire underneath at its point of greatest deflection potential, doesn't do much to actually mimic how a superstructure actually responds to fire.

A the ends are unsupported
B the beam has zero lateral support
C the fuel source isn't even close to the fuels available in a typical office fire
D the beam is subject to consistent heat rather than fluctuating as in a real fire
E the fire has an unlimited fuel source, or at least its fed till the point of failure
F the several NIST tests on beams in fire used beams with no fire retardant
G and the list goes on and on and on

In the end, there was no excuse for not mapping the fall pattern of all three of the WTC buildings. Its very common even outside of the investigatory process for companies to review the results of there work not simply by watching the film, they film pretty much every controlled demo for "quality purposes" but also by measuring the the size of the debris and noting where the major structural components landed. Its basic business, more explosives = more risk, so use as little as you have to. Only way to know just how little you really need, study the damn pile. Its a no brainer. Assuming they used experienced demolitions crews to remove the rubble piles, the guys would have been very familiar with the process, hell a lot of them even kinda enjoy it cause it breaks up the monotony. Imagine yourself standing there being sprayed with hot slag and sparks off a torch on a hot day, wearing leathers, hard hat, long sleeves, welding gloves, the works, and its 95 degrees out. Wanna take a break and go record the field marks on the beam your working on soon as that cuts through ? Maybe even take that stupid hat off for a moment and take a slug of water ? The guys generally have no problem doing this kinda thing. Even if you told them not to, they'd still just out of habit, start every new beam by looking it over not just for the lay, but also for the marks, 12/48 or whatever. Thats 12 wide at the flange and 48lbs per foot by the way. Hell I've even probably got my Dencol book around here somewhere with all the notes in it.

Deal is these so called experts probably never worked steal a day in there lives.

If you want an expert, ask a USW man what he thinks of these films, my neighbor for instance.
 

Boston

Active Member
The principal is exactly the same. The vertical members (the columns in the building, or the sides of the can) transfer the load down to the ground. The stability of the structure is maintained by the rigidity of the exterior of the structure.

There are significant differences of course. The most significant are those due to scale. The can is much stronger than WTC7. It can support thousands of times its own weight. WTC7 would have difficulty even stacking one more WTC7 on top of it. WTC7 on the other hand had much greater stability, due to it internal structure, which the can is lacking. If the can had a similar internal structure, then it would require much more than a light touch to make it collapse.




When is a steel column like wet noodle? When it buckles.

A column can support a lot of weight when it's vertical. But only a tiny fraction of that weight when it is not longer vertical - when it's bent away from the vertical plane. Just like the can, the vertical walls of the can transfer the load perfectly, but as soon as they are out of line, then it's wet noodle time.

Remember what the NIST hypothesis is here:

A) The interior collapses asymmetrically, leaving the exterior

Which I don't think is even possible, the connection strength of each major structural component is huge. Stronger than the beam itself actually. they often virtually double the width of the steal with connecting plates held by dozens of 3/4 drift bolts. Ive ordered pallets after pallets of these when I was a kid working on various buildings. The last thing to break free with zero visible deformation of the supporting structure would be one of those, let alone all of them. In building demolitions they tend to remove the majority of these bolts so the connector plates come apart easier. They also jack hammer holes in any concrete columns as well as remove a lot of interior webbing.

B) The exterior, lacking support, collapses like a can being crushed.

sure but thats not what we saw, it was nothing like that can being crushed actually, in the can analogy its a monolithic unit, the sides can only crush inward. But in a typical building failure, the structure or the components follow the path of least resistance to the ground. The two fall pattern are completely different. If you want a building to all fall inwards, you've gotta put quite a bit of effort into it.

It's not like the entire building with all the interior columns collapses all at the same time.

Not so Mick, its exactly like that. What we see in the films is a progressive failure of the penthouse structure, followed by the perfect failure of every single vertical member at exactly a precise time such that it elicits one of the most perfect vertical collapses you could ever ask for. The building collapses inward on itself through the path of most resistance. Sure some stuff fell off the debris pile but it is a 47 story building, even if most of it landed in the basement you're still going to have a substantial pile of stuff. I'm going to have to call BS on this one, based on the film evidence. That dropped like a rock and at about the same speed. Which brings us to another question, how to all four corners drop at the exact same time ? at the same rate ? in the same direction ? directly downward through the path of most resistance ?
Its exactly like the entire building and all the interior columns collapsed at the same time

Back to the can. Imagine you were to give it some internal support by filling it with water before standing on it. You then turn it upside down and stand on it. The water will drain out, and then the can will collapse. This simulates the collapse order to wtc7.

so where's all the windows blowing out of wtc7 as the air mass is forced out of the way of the debris ? OK a few isolated windows are broken and continue to break as minor fires influence air temp and patterns within the structure but if what your suggesting is true, or rather what NIST is suggesting, their would be a massive reaction in the remaining structure to this mass of falling debris, like hundreds of windows all blowing out in a progressive patters as steal connections shatter ( speaking of which steal bends not shatters ) and tons and tons of debris goes bouncing off the interior of those walls. Sorry Mick, the NIST hypothesis just doesn't fit the film evidence, nor does there model for that matter. Which also shows the exterior shedding debris as the interior supposedly fails.

The building seems to collapse symmetrically for the reasons NIST gave. The exterior is stronger than the interior.


If the exterior is stronger than the interior, then it was designed to impart that excess strength on stabilizing the interior. Remove that interior and you loose load off the remaining structure, its maximum allowable load remains the same, but the loads on it are reduced. The system becomes even more stable particularly in the vertical direction, the direction we all can see the building collapsing in. This situation is particularly strong in the corners, where the exterior walls, with all that excess strength, which are now under even less loading due to your assumed collapse of the interior, should be the absolute last things to collapse straight down and disappear completely into the debris pile. It is a ludicrous suggestion.

There is something really fishy going on at wtc7

Even NIST said their explanation has "a low probability" which is a nice way of shrugging your shoulders and going "oops" we no nothing.
 

Mick West

Administrator
Staff member
You raise several points, and forgive me if I only handle one at a time, but I think it's better to go deep than wide.

A) The interior collapses asymmetrically, leaving the exterior

Which I don't think is even possible, the connection strength of each major structural component is huge. Stronger than the beam itself actually. they often virtually double the width of the steal with connecting plates held by dozens of 3/4 drift bolts. Ive ordered pallets after pallets of these when I was a kid working on various buildings. The last thing to break free with zero visible deformation of the supporting structure would be one of those, let alone all of them. In building demolitions they tend to remove the majority of these bolts so the connector plates come apart easier. They also jack hammer holes in any concrete columns as well as remove a lot of interior webbing.

But the key here is what type of connections were used in the interior of the building. What you describe (Stronger than the beam itself actually. they often virtually double the width of the steal with connecting plates held by dozens of 3/4 drift bolts.) Sounds like moment resisting connections as used in the exterior. Most of the interior connections were seated connections, or similar. The beam simply rested on a metal plate that was welded to the column, and then there was a smaller top clip on top of that (or web clips in some cases). The beam is only attached to those plates with with two bolts on the top and two on the bottom. And sometimes the beams were at an acute angle to the column.


Brief description from NIST page 15 (pdf 59)



And the key reason the interior fell: (p342, pdf 386)

More detail is then gone into on the strength of the connections. But the key point there is that it's a "gravity frame". It's only meant to withstand gravity, not any lateral or twisting forces (which the exterior does, because of the wind loading). So it did not hold up well under thermal expansion.

Simplified:
  • Weak connections on the interior (seated and
  • Strong connection on the exterior
  • Interior collapses first by progressive collapse
  • Exterior collapses by buckling after total loss of lateral support.

Would you agree at least that there was this difference in the connection strength between interior and exterior?
 
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Boston

Active Member
More detail is then gone into on the strength of the connections. But the key point there is that it's a "gravity frame". It's only meant to withstand gravity, not any lateral or twisting forces (which the exterior does, because of the wind loading). So it did not hold up well under thermal expansion.

Simplified:
  • Weak connections on the interior (seated and
  • Strong connection on the exterior
  • Interior collapses first by progressive collapse
  • Exterior collapses by buckling after total loss of lateral support.
Would you agree at least that there was this difference in the connection strength between interior and exterior?

There is always a difference between the connection strength of the interior and the exterior steal work. Its due to the fact that different loads are being imparted on by different structures. The exterior wall of a steal framed building is designed to resist shear and load. The interior floors provide lateral resistance and impart load on the exterior wall. Its two completely different systems, thus they use different types of connectors, and of differing strength characteristics.

point A
I'd characterize this type of construction as standard, gravity loading, what the rest of the world calls seated connections are very quick to assemble. Beams do not have to be suspended in place while some poor sot climbs out there and sets a few drift pins, hoping the wind doesn't pick up. I'd not refer to the interior connections as weak, I'd instead suggest that they were of a standard type used in hundreds of buildings that had never before been found inadequate in a fire situation. Or at least not to my knowledge. I'd be curious to compare the construction details of the Madrid fire to this one. something tells me its the same kinda thing, but that building sustained what a 24 hour uncontrolled burn, and didn't collapse. ;-)

point B
Again I'd characterize the connections used in the exterior of a steal framed structure as adequate to impart the forces necessary from member to member, because these forces are different, they're typically of stronger construction, for instance, shear resistance which is designed to keep the columns vertical and resist wind loading requires an angled connection at some point. That angled connection plate tends to be larger and use more bolts. Cable bracing might be used but typically a shear wall or two are also inside the building as well. So suggesting that the "entire" interior was of inferior construction is hardly accurate. I'd be damn surprised if at several points along the long sides of the building there was specifically designed shear walls leading most likely across the entire width of the building. At the least there may be some cable bracing. Often elevator shafts are used as shear bracing for this type of wall.

Point C
There is no evidence of an interior collapse, Even if there was some asymmetrical failures inside the building there would remain various fire breaks within the building. All commercial buildings are required to have fire doors and fire breaks every x number of square feet. These doors act automatically when a fire is detected. The fire breaks are generally double walled structures with often 2 layers of 5/8 rock facing each other, 1/2 rock on the visible side against steal framing, if I remember it has to have a 2 hour burn time in order to meet code. Also the floors are typically light weight concrete over corrugated steal, doesn't burn at all. If the trusses bent, they'd still have to snap those connections, that action is what I'm saying isn't possible without major visible consequences to the exterior, particularly through the windows. You'd see shattering glass like crazy. And thats not even what would likely happen if you lost a single major support beam. Major beams tend to be not only bolted but also welded, making for a monolithic structure. Your surely going to bend that outside column would one of those begin to deform.

Point D
The exterior didn't collapse by buckling, it fell straight down. This isn't the likely consequence of buckling, which by the way would be most likely to occur where the column is under the greatest stress, the middle, where those lateral components are providing the most assistance to the column, not were its strongest, the bottom, where the foundation itself is imparting absolute lateral resistance, and certainly not all columns would fail in the least likely place at the same time. The columns don't need the lateral support anyway, once you ( assuming the interior had collapsed ) remove the load, IE the interior somehow fell apart, particularly in the corners where they get all kinds of lateral support from the other exterior wall perpendicular to the first. The only way to get a building to act like what we see in the film evidence is to simultaneously release kinetic energy sufficient to overcome the designed load limit, such that the building falls straight down through the path of resistance snapping all connective devises along the way. Not only is there no buckling evident in a single bit of film evidence, but buckling doesn't even cause this type of collapse. Period. Its a ludicrous suggestion
 

Mick West

Administrator
Staff member
Well I wish I had the time to discuss this more. I'd encourage you to look into the Madrid fire (Windsor Tower) and to read NCSTAR 1-9 in more detail to see what the actual theory is. Particularly how column 79 could have failed, due to buckling. And where the exterior bucking happened.

Windsor tower:
 

Boston

Active Member
No worries, but this buckling simply isn't evident in the film evidence, and it certainly wouldn't have occurred at the base where there is ultimate stability imparted into the structure in all directions. Which is exactly what a foundation is designed to do. Not only that but if there was debris falling into the basement it would have provided additional support to the exterior walls of that foundation not less. Even further minimizing the possibility that foundation structure would have failed in some way to initiate an instantaneous global collapse

I realize you are sticking with that NIST explanation, but that explanation has so many holes in it, its ridiculous they even suggested it.

One thing they are most definitely ignoring is the chance that all four corners would ever let go at once. at least 2 were never even subjected to fire or structural damage, 3 not to structural damage and at least 2 not to fire. Its just silly to insist they would all let go at once particularly "if" a substantial part of there load was eliminated through the alleged collapse of the interior wall and floor structures.

I also noticed no references to the partition/fire walls or the action of automated fire doors, which would have isolated large areas of the structure from fire entirely leaving them undamaged by either heat or structural issue. Large buildings like this have expansion areas and are often actually several buildings just kinda pasted together, but without seeing the prints its hard to tell.

I would reiterate post 188 but no sense beating a dead horse.

In a nut shell I call BS on the NIST explanation, I'd also note that the Windsor tower did not collapse, OK it shed some debris, but the structure remained standing and in no way resembled the reaction we saw in the WTC7 failure. Not only did the Madrid fire result in only a partial failure but that failure was asymmetrical and did not initiate at the bottom of the structure but the approximate middle exactly as would be expected. Also if you notice the elevator core in the worst of the affected area remained intact.

Again all the evidence being presented does nothing but to refute the NIST explanation given. Its like shootin fish in a barrel. There's just no way.


and this one, aprox 2 minutes in, comment "no buckling at all"

 

Mick West

Administrator
Staff member
The buckling was not at the base, it was probably around the 7th to 14th floors.



The Windsor Tower did not fully collapse because it was of radically different construction.
 
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lee h oswald

Banned
Banned
actually that wasn't a controlled demolition at all, it was an apartment building that just fell over on its own, but it did so due to a random failure, "down low" which for a second time shows that a random asymmetrical failure "down low" doesn't result in the instantaneous failure of every column resulting in a symmetrical collapse. It instead results in the building falling over.

Quite so.
 

lee h oswald

Banned
Banned
The buckling was not at the base, it was probably around the 7th to 14th floors.

The Windsor Tower did not fully collapse because it was of radically different construction.

The Windsor Tower probably didn't collapse because it was of a radically inferior construction, and only burned for three times longer.
 

SR1419

Senior Member.
I'd also note that the Windsor tower did not collapse, OK it shed some debris, but the structure remained standing and in no way resembled the reaction we saw in the WTC7 failure.

It did more than "shed some debris"- The upper floors completely collapsed- only to be arrested by a concrete floor.


http://www.concretecentre.com/default.aspx?page=823
 

Mick West

Administrator
Staff member
Point D
The exterior didn't collapse by buckling, it fell straight down.


Consider this. Supposed the columns were all severed at the base by explosives. How then would the columns fail?

Clearly the building would fall down, but why would it not just fall 2 feet and then stop? What happens to the rest of the building? How does the building "fall straight down" when all you've done is remove 2 feet from beneath it?
 

Mick West

Administrator
Staff member
The Windsor Tower probably didn't collapse because it was of a radically inferior construction, and only burned for three times longer.


Why did the bits of the Windsor tower that collapsed actually collapse then? Why didn't the bits that didn't?
 

lee h oswald

Banned
Banned
Btw, B - do you know of any resource for engineering or architectural construction detail (specifically - and including the stairwells/lift shafts/service runs and their interactions) of the towers' cores, by any chance? Ta, and keep sluggin' bro!
 

Boston

Active Member
Consider this. Supposed the columns were all severed at the base by explosives. How then would the columns fail?

Clearly the building would fall down, but why would it not just fall 2 feet and then stop? What happens to the rest of the building? How does the building "fall straight down" when all you've done is remove 2 feet from beneath it?


Because thats not how a controlled demolition works. Its a very scientific process, enough kinetic energy must be released by removing a sufficient amount of structure that it overcomes the buildings design limit. OK actually they reduce that design limit by removing certain key components but, the calculations are the same, or relatively so.

If you actually watch a controlled demolition you'd quickly not that typically an entire floor is removed if not several. That means the entire floor, not a segment, not a corner, the entire thing, poof gone. Except interestingly enough, the corners, which they know are the strongest part so they typically want them to be "pulled" inward virtue of the interior structures failure ;-)

here's an excellent example of 2 stage demolition, first the connecting structures are weakened by workmen, next they are set with charges to further weaken them, finally the areas immediately below them, are removed allowing the structure to drop sufficiently it develops enough kinetic energy to overcome the loading capabilities of the rest to the structure.

 

Boston

Active Member
Why did the bits of the Windsor tower that collapsed actually collapse then? Why didn't the bits that didn't?


because thats how fire effects a structure, asymmetrically, the parts that did shed from the structure were likely the most effected by fire and the least supported in lateral resistance, I'd also note that just like the Madrid fire the WTC 7 fire did not reach all the way to the bottom of the building, but unlike the Madrid fire the WTC 7 fire did not totally involve the buildings upper stories at any one time, or for that matter ever. The WTC 7 fire was substantially smaller and more scattered, burned for less time and at a lower temp, yet supposedly resulted in a total instantaneous global collapse exactly synonymous with a controlled demolition, yet the Madrid building remained standing. Sorry but the NIST explanation is pure horse crap.

Did anyone else notice how uncomfortable the NIST investigator was trying to deny the existence of molten metal at the WTC site, wow, talk about obviously lying.
 

Boston

Active Member
It did more than "shed some debris"- The upper floors completely collapsed- only to be arrested by a concrete floor.


http://www.concretecentre.com/default.aspx?page=823

No it was arrested by the elevator shaft and surrounding structure that is designed to provide lateral stability to the building, WTC7 would have had a synonymous structure, likely several for a building that large. Sooooo where did that go and how did it just disintegrate completely right along with everything else in the building regardless of strength characteristics

Another little tid bit is that the WTC building was largely unaffected by fire, whereas everything in the Madrid fire that actuall fell off the building had been totally engulfed in flames for something like 12 hours previous to the collapse.

Feel free to correct me on the 12 hours part, but it was a significant amount of time vs the WTC 7 in which the vast majority of the building wasn't subjected to fire stress at all.
 
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