WTC Collapse - A Question of Fairness.

Originally posted by HowardRoark
The floor truss beams in the Caracas tower were connected to intermediate beams that ran from column to column and the columns were much closer together than the WTC towers. Also, note that the fireproofing was still intact after the fire. The same could not be said for the WTC where the integrity of the fireproofing was questionable even before the planes hit.

The relevance of all of this is based solely upon the intensity of the fires. Again, look at the samples from the WTC. The steel exposed to fire was not beyond around 250 degrees Celsius. There is no way the steel would lose enough strength in fires that cool to cause collapse. And again, there would have to be an average of 60% column failure. The temperatures shown by NIST indicate less than 1% loss of integrity by conventional knowledge of steel and integrity loss via heat.

You're always so keen to point NIST out Howard, so why not pay attention to the amount of heating to the steel they're giving you? All of the above is irrelevant given the weakness of the fires.

Originally posted by bsbray11
There was a role of concrete in the construction of the Windsor Building that was not present in the WTC, or, as far as I know, the Caracas Tower, and thus I refrain from referring to the Windsor Building.

Well, from what I understand the Windsor building had a reinforced concrete core, unlike the WTC. It's just that on this page here:

www.concretecentre.com...

Which appears to be a professional site which is described as the following on the home page:

The Concrete Centre is the central development organisation for the UK cement and concrete industry and our aim is to assist all those involved in design and construction to realise the full potential of concrete.

Has this to say regarding the Windsor building... (emphasis mine)

Because of the height of the structure and the extent of the blaze, firefighters could only mount a containment operation and ensure that neighbouring buildings were protected. The fire eventually finished 26 hours later, leaving a complete burn-out above the fifth floor. The steel-glass façade was completely destroyed, exposing the concrete perimeter columns. The steel columns above the 17th floor suffered complete collapse, partially coming to rest on the upper technical floor. The insurance value of the total damage caused was €122 million.

[...]

Crucially, the building remained standing despite the intensity of the fire. An investigation is underway between Spanish technical agency Intemac and UK authorities including Arup Fire, the University of Edinburgh and the concrete industry including Cembureau, BCA and The Concrete Centre. Preliminary findings suggest that a combination of the upper technical floor and the excellent passive fire resistance of the tower's concrete columns and core prevented total building collapse.

www.concretecentre.com...

Bearing in mind the different construction, the elements of the structure that relied on steel appear to have not done to well.

Which would appear to make this:

I'm not familiar with the exact structure of the Windsor Building, but I understand that rather than having a steel frame, it was supported by concrete that was reinforced by steel. I would imagine that the failure was related to this more than the effect of the fire upon the steel, and thus you have no such failures from actual steel skyscrapers.

Wrong..

You'll notice that the building did not globally collapse upon itself into a pile of steel shards and conrete dust, too. What of it did collapse was very different than any part of the WTC collapse.

As we said though, different building, different construction, different size....

I'm sure you realise that construction method is just as important as construction materials.... For instance if you tried to build a bridge out of stone without an arch and keystone, it would collapse.. Which is why it confuses me when you compare a building which lacks the key components theorised to have failed in the WTC collapse and of substantially different construction to the WTC.....

[edit on 17-1-2006 by AgentSmith]

No, there has never been a plane that hit a building of that size,except the bomber that hit the Empire state building at the end of WW2. interesting read on what happened.

The airliner on 9/11 entered the building, and in a flash all fireproofing was removed from the steel support. Heat did reach significant temperature to cause unstability. Remember, this is a 100+story building, that in effect is bieng cut in half and still asked to support the upper 25 or so floors. Gravity played a large part in this, not explosives. Basic physics. The supports buckled, and the building began coming down. There was an excellent special on National Geo that explained it graphically and quite well.

It also has never been proven that there was nothing that hit or affected WTC 7 after the crash.

As I said, I'm not familiar with the structures of the Windsor Building. Nor with the Caracas.

But on further research, inspired by your post, I found this:



This is an image of a typical floor plan, albeit a small one (the expanded image is unfortunately missing).

If you look closely you can see the labels for the steel reinforcement in the core columns (the upper diagram in the image, which reads "Typical Floor between 17th and 27th"). As you can see, the vast majority of the floors were comprised of concrete with very little steel inside as support.

The following image shows the core support columns, again, mostly concrete, with thin sections of internal steel for support:



This page provides further info on the steel reinforcement:

A typical floor was two-way spanning 280mm deep waffle slab supported by the concrete core, internal RC columns with additional 360mm deep steel I-beams and steel perimeter columns.

So the steel core support for a typical floor was 36cm (14in) -deep I-beams as shown in the floor plan images above, and this was covered in concrete.

The same source also provides that on and above the 17th floor, fireproofing on the steel was not yet commenced (with the exception of the 18th floor being partially completed). That means no fireproofing at all above the 17th floor for the whole 18 to 20 hours for the fire, which maxed around 800 degrees Celsius. The core steel was also covered in concrete, which poses another problem, but I'll post that in a sec.

For the perimeter columns, we have the following:



The steel reinforcement on the perimeter columns was thin (much thinner than the WTC perimeter columns, notice), which served to inhibit the steel's conduciveness to heat. There was not as much area to spread the across. And again, no protection whatsoever for these thin bars above the 17th/18th floors.

The 9/11 Research Site makes the following points regarding the Windsor structure of steel-within-concrete:

* Steel is a good conductor and concrete is a poor conductor of heat. Thus in a fire, a steel frame will conduct heat away from the hotspots into the larger structure. As long as the fire does not consume the larger structure, this heat conductivity will keep the temperatures of the frame well below the fire temperatures. The same is not true of steel-reinforced-concrete structures, since concrete is not a good thermal conductor, and the thermal conductivity of the rebar inside the concrete is limited by its small mass and the embedding matrix of concrete.
* Fires can cause spalling of concrete, but not of steel. This is because concrete has a small percentage of latent moisture, which is converted to steam by heat. Thus, a large fire can gradually erode a concrete structure to the point of collapse, whereas a fire can only threaten a steel-framed structure if it elevates steel temperatures to such an extent that it causes failures.

Originally posted by AgentSmith
I'm sure you realise that construction method is just as important as construction materials.... For instance if you tried to build a bridge out of stone without an arch and keystone, it would collapse.. Which is why it confuses me when you compare a building which lacks the key components theorised to have failed in the WTC collapse and of substantially different construction to the WTC.....

In the case of the Windsor it appears to have been the materials. Now, if you build something in a stupid fashion, then the construction method will certainly come into play, but I'm assuming that these buildings are all sturdy until introduced to high enough temperatures of fire.

Again, the steel samples of the WTC show no heating above a rough 250 degrees Celsius. You've yet to compensate for this problem, as those temps will obviously not attribute much damage to the initial impact damage, and thus the whole reasoning behind the fall of the two towers becomes unexplained at best for you guys.

Originally posted by esdad71
The airliner on 9/11 entered the building, and in a flash all fireproofing was removed from the steel support.

This is,

(a) irrelevant, because the steel was not heated sufficiently anyway, as provided by the very steel samples from the WTC that NIST tested, and

(b) conjecture.

Heat did reach significant temperature to cause unstability. Remember, this is a 100+story building, that in effect is bieng cut in half and still asked to support the upper 25 or so floors.

This makes absolutely no difference. Think about it. Think of, say, floor #10 of either tower. When the building is hit, floor #10 is only carrying the extra weight of the plane, minus much of its fuel load and the debris in concrete dust and steel that was ejected upon the impact.

You could say the same for every single floor leading up until the impacted floors. With those floors, there was less than 15% column severing, and the weight load of the top floors was redistributed to the remaining 85% of columns still intact. The floors above impact, aside from being irrelevant, also carried the same weight.

So the weight loads really did not change except for the columns of the impacted floors, and for the lower floors, the added weight of the plane (which is comparatively is not much at all considering what the buildings were legally obligated to carry according to NYC Building Code).

And again, no evidence of either severe fires of critically heated steel. No glowing, no tested samples showing above 250 C, etc. That is, until after the collapse.

Gravity played a large part in this, not explosives. Basic physics. The supports buckled, and the building began coming down.

Basic physics also maintains that the impulse of a body is a fixed amount, not infinite, and that angular momentum is conserved. And yet you see neither of those principles being maintained by the collapses, as the collapse speed remained constant and steady, despite a number of disadvantages all the way down, from loss of driving mass to increasing column thickness, and the angular momentum indicated the loss of a connection to the fulcrum. The latter begs the question, how does a cap crush floors that it's not even touching?

Also, in regards the supports buckling and thus allegedly causing the collapse, I've always liked this post, by BillyBob on the Steven Jones thread on ATSNN:

Originally posted by billybob
nist reports that the outer wall was pulled in by the sagging floors. this indicates that the floor joist connections have more strength than the walls. yet it was these same connections that are supposedly the ones that were underdesigned and consequently, failed. obviously, the floors are designed to carry mostly a gravity load, so the true strength of these joist seats isn't their ability to pull laterally(although they did help transfer those loads, too), but rather their ability to resist downward loading.

so, in other words, it's kinda like snow tires being outperformed by racing slicks on black ice.

if the floors were strong enough to pull the wall in, then the idea that these connections were the lynch pin for the whole tower is ridiculous. especially since the ones that did the alleged pulling were also the first to fail. the magic joist seats simultaneously initiated the collapse by pulling in the whole side of the building, and then the other several thousand completely undamaged, unheated, uncompromised connections managed to offer ZERO RESISTANCE for the rest of the collapse.
of course, as already pointed out, if the floor joists connections fail first, how does the concrete get crushed into a fine powder? you can't grind something between two other things unless there actually are two other things. a floor section which has failed is then falling and can offer no resistance for the crushing of concrete.

i've never seen someone grind up some herbs and seeds with just a pestle. you need the mortar, too. same deal. crushing something as hardy as concrete into powder requires a great downward force, and an EVEN GREATER upward resistance.

Of course, there you have two problems with the very fundamental logic of the collapses, but nonetheless, the one regarding the buckling is right there.

It also has never been proven that there was nothing that hit or affected WTC 7 after the crash.

Nothing major did, man. The damage to nearby buildings from large pieces of plane debris has been pretty well mapped out by the feds. The only damage WTC7 suffered prior to collapse was from the collapsing buildings. The fire that broke out in the building is still unexplained, and the nature of the collapse that followed especially so.

[edit on 17-1-2006 by bsbray11]

And again, no evidence of either severe fires of critically heated steel. No glowing, no tested samples showing above 250 C, etc. That is, until after the collapse.

How can you know the damage was from after the collapse?

www.civil.usyd.edu.au...

Eventually, the loss of strength and stiffness of the materials resulting from the fire, combined with the initial impact damage, would have caused a failure of the truss system supporting a floor, or the remaining perimeter columns, or even the internal core, or some combination. Failure of the flooring system would have subsequently allowed the perimeter columns to buckle outwards. Regardless of which of these possibilities actually occurred, it would have resulted in the complete collapse of at least one complete storey at the level of impact.

Once one storey collapsed all floors above would have begun to fall. The huge mass of falling structure would gain momentum, crushing the structurally intact floors below, resulting in catastrophic failure of the entire structure. While the columns at say level 50 were designed to carry the static load of 50 floors above, once one floor collapsed and the floors above started to fall, the dynamic load of 50 storeys above is very much greater, and the columns were almost instantly destroyed as each floor progressively "pancaked" to the ground.

Gravity bought it down, not demolitions.....

Many conspiracy theorists point to FEMA's preliminary report, which said there was relatively light damage to WTC 7 prior to its collapse. With the benefit of more time and resources, NIST researchers now support the working hypothesis that WTC 7 was far more compromised by falling debris than the FEMA report indicated. "The most important thing we found was that there was, in fact, physical damage to the south face of building 7," NIST's Sunder tells PM. "On about a third of the face to the center and to the bottom--approximately 10 stories--about 25 percent of the depth of the building was scooped out." NIST also discovered previously undocumented damage to WTC 7's upper stories and its southwest corner.

NIST investigators believe a combination of intense fire and severe structural damage contributed to the collapse, though assigning the exact proportion requires more research. But NIST's analysis suggests the fall of WTC 7 was an example of "progressive collapse," a process in which the failure of parts of a structure ultimately creates strains that cause the entire building to come down. Videos of the fall of WTC 7 show cracks, or "kinks," in the building's facade just before the two penthouses disappeared into the structure, one after the other. The entire building fell in on itself, with the slumping east side of the structure pulling down the west side in a diagonal collapse.

According to NIST, there was one primary reason for the building's failure: In an unusual design, the columns near the visible kinks were carrying exceptionally large loads, roughly 2000 sq. ft. of floor area for each floor. "What our preliminary analysis has shown is that if you take out just one column on one of the lower floors," Sunder notes, "it could cause a vertical progression of collapse so that the entire section comes down."

There are two other possible contributing factors still under investigation: First, trusses on the fifth and seventh floors were designed to transfer loads from one set of columns to another. With columns on the south face apparently damaged, high stresses would likely have been communicated to columns on the building's other faces, thereby exceeding their load-bearing capacities.

Second, a fifth-floor fire burned for up to 7 hours. "There was no firefighting in WTC 7," Sunder says. Investigators believe the fire was fed by tanks of diesel fuel that many tenants used to run emergency generators. Most tanks throughout the building were fairly small, but a generator on the fifth floor was connected to a large tank in the basement via a pressurized line. Says Sunder: "Our current working hypothesis is that this pressurized line was supplying fuel [to the fire] for a long period of time."

WTC 7 might have withstood the physical damage it received, or the fire that burned for hours, but those combined factors--along with the building's unusual construction--were enough to set off the chain-reaction collapse.

FEMA made the quick assumption that there was minimal damage, but it has latter been found that there was significant damamge from falling debris 10 stories--about 25 percent of the depth of the building was scooped out, and it has been found that previously undocumented damage to WTC 7's upper stories and its southwest corner were not reported.

www.popularmechanics.com...

Read through all the articles, and realize that the truth is out there, Long live Google!!!!

Originally posted by esdad71
How can you know the damage was from after the collapse?

I was referring to the tested samples noted in the NIST Report, which is a report from a government agency. They state that of all the samples they tested, they found no steel exposed to temperatures higher than 250 degrees Celsius.

However, photographs exist of steel being pulled from Ground Zero that are glowing, indicating temperatures in excess of 250 C and closer to at least 600 C. Also the thermal imaging shows temperatures much higher than 250 C coming from Ground Zero.

Eventually, the loss of strength and stiffness of the materials resulting from the fire,

Non-existant based on all available evidence.

combined with the initial impact damage,

...of a small minority (>15%) of columns.

would have caused a failure of the truss system supporting a floor, or the remaining perimeter columns, or even the internal core, or some combination. Failure of the flooring system would have subsequently allowed the perimeter columns to buckle outwards. Regardless of which of these possibilities actually occurred, it would have resulted in the complete collapse of at least one complete storey at the level of impact.

Once one storey collapsed all floors above would have begun to fall. The huge mass of falling structure would gain momentum, crushing the structurally intact floors below, resulting in catastrophic failure of the entire structure. While the columns at say level 50 were designed to carry the static load of 50 floors above, once one floor collapsed and the floors above started to fall, the dynamic load of 50 storeys above is very much greater, and the columns were almost instantly destroyed as each floor progressively "pancaked" to the ground.

The problems with this theory have been expounded in virtually every WTC thread. There were physics principles that were violated during the collapses, including the momentum mentioned, which, again, remained constant despite a large number of disadvantages, and the perfect symmetry all the way down defies chaos theory, and this was undoubtedly a big problem area with tons of chaotic variables. Then there were the explosions in the facade before the collapses reached the same region, which have been attributed to air, even though the buildings were being destroyed floor by floor and there was absolutely no means by which the buildings could have become pressurized (Note the ejected debris: the building was being utterly destroyed, people; last time I checked, air can go through giant-butted holes, and certainly would before so much pressure built up as to magically send an air rocket across a floor to blow out a random chunk of column). Etc.

What you just quoted is essentially the pancake theory. It's nothing new here; the controversy revolves around it.

Gravity bought it down, not demolitions.....

Who are you trying to reassure with this?

Regarding Building 7.

I want you to try to rationalize how isolated pockets of fire in WTC7, along with perimeter damage, caused this to happen:

I am giving my own rational view,that's all. I have read the articles on the pancake principle, but I do not believe it was a controlled demolition. I beleive one thing, you believe another. I ahve read to much for both sides that what is needed is proof, proof that there were multiple explosions that bought it down. Explosive residue. a trigger..a timer....anything. That is why i cannot be convinced. THere is nothing of the sort, and there would have to be something left. Is there any reported blast damage on any of the support structure? If they checked it and know how hot they got, they would know that, right?

Originally posted by esdad71
THere is nothing of the sort, and there would have to be something left. Is there any reported blast damage on any of the support structure? If they checked it and know how hot they got, they would know that, right?

Of course there isn't, but the answer for that is "Of course there isn't, it would be 'covered up' and never make the public eye.".
Don't you realise, only arguments with no proof and arguments to justify why there isn't are used.
Also note how one minute the fact not much steel was available is reason for conspiracy to cover up real events, yet when presented with viable models showing adequate temperatures for concern, the lack of evidence suddenly comes into favour with statements regarding the relatively minimal temperatures subjected to the samples available for analysis.
Note how evidence is manipulated in and out of favour to suit the argument, note how when this is pointed out the argument "You do it to" is used, note who acts like they are following some sort of noble cause and are trying to help fellow man...
I still think it's red herrings to send the few that question into the realms of oblivion along with the majority of the population, leaving very few (if any) people to get to the crux of the matter..
Most, if not all, your arguments have had equally viable theories attached to them with less sinister explanations.. You scorn these explanations and mock them due the extraordinary events and circumstances witch could cause them, yet expect us to believe an even more preposterous idea in the sheer number of hurdles that would have to be overcome. On the face of it, explosives sounds simple, but giving the scale of the planning and preparation, in the tools and people required, along with the avoidment of suspicion, it seems rather radical in thinking. Yet you quickly dismiss with a swipe of the hand alternative explanations that could account for the various anomalies experienced on that day.
Lots of interesting and unusal co-incidences and events occur to people every day, usually these are not significant enough to stick in our minds or those of others for any real period of time, yet they are substantial enough to warrant curiosity.
With the events surround 9/11, there are significant episodes which will always stay in people's minds, there are many interesting anomolies that warrant serious investigation.. But still we have to be open to accept that there are extraordinary scientific principles at work here that do not necessarily include undisclosed foul play by anyone on any level.. By ignoring these possibilities it could mean wasted efforts at the cost of knowing the truth about 9/11 and also at the cost of advancements in civil engineering.
All I'm really saying is that the theories which incorporate explosives and such like are, when looked at in detail, far more complex and difficult to achieve they seem on first impressions.
Ideas which revolve around science, even if requiring extreme circumstances, equally need to be looked at and considered.
It is said many times that no steel frame building has ever collapsed due to fire as the WTC did, however and thankfully, there have been no other incidents involving a building built like the WTC, at the same scale, with the same methods and with the same scenario.
For both sides of the argument it is not a fair comparison due to this, it really holds no water. Sadly even the most powerful computers are too slow to build an accurate model and subject it to the same conditions that happened that day. Maybe some time soon in the future with advancements in technology this will be overcome, but we are probably some time off.
But based on what we do have, we need to make judgements - the case stands that even now no-one has even claimed to have seen any evidence of explosives on material recovered. Certainly not to my knowledge anyway and I'm sure it would be big news on the Internet if there had. It's almost disappointing that no-one has even bothered to make an attempt to pretend they had, but then maybe that shows even more that there is really nothing to see.. No pieces of blasted metal picked up by people in the vicinity, put out on the Blogs or eBay....
On the physics side of things it goes into realms that go over me and I suspect a lot of other people, but you seem to see people arguing equally well on both sides, saying the other is lying, sounding equally convincing.. No real conclusion really, seems to show even more how a lot of us have to rely on our 'superiors' and form a sort of hierarchy based on who we 'like' and what we 'believe'.. heh..deja vu... how amusing..

[edit on 17-1-2006 by AgentSmith]

Originally posted by FEMA

No steel-frame building, before or after the WTC buildings, has ever collapsed due to fire.

In light of the above statement is it fair to ask? . . .
1) Has any steel-frame building, before or after the WTC buildings, ever had a jet airliner fly into it?
2) Has any steel-frame building, before or after the WTC buildings, ever been hit with such lateral force?
3) Has any steel-frame building, before or after the WTC buildings, ever sustained itself after the resulting impact of a jet airliner, explosion and burning of 11,000 gallons of fuel?
4) Has any steel-frame building, before or after the WTC buildings, ever sustained itself after the resulting impact of a jet airliner, explosion and burning of 23,500 gallons of fuel?

No steel-frame building, before or after the WTC buildings, has ever collapsed due to fire.

In light of the answers to the 4 questions, is the above statement fair?

Yes it's fair. An larger airliner hit a large steel building in Holland and the building only partially collapsed:

Date of Accident: 04 October 1992
Airline: El Al Cargo
Aircraft: Boeing 747
Location: Amsterdam, Netherlands

Shortly after takeoff, the aircraft's no.3 engine separated from the wing, tearing out the leading edge slats and the no.4 engine when it did so. The trailing edge flaps on the right wing were also severely damaged. As the crew began to slow the airplane as they turned onto final, the right wing began to stall due to the lack of leading and trailing edge devices. Slowing through 160 knots with the flaps extended to 25°, the right wing entered a deep stall and the crew lost control of the airplane. The 747 impacted an apartment building in the Bijlmermeer district of Amsterdam at nearly a vertical nose down attitude. Corroded pins within the engine pylon caused the engine to separate.

Also, I noticed you mentioned nothing about WTC 7, the one that wasn't hit by a plane.

So who's statement is really fair?

.

bsbray11, interesting find on the Windsor Tower.


The following quotes are interesting.

The building was subjected to a three year refurbishment programme of works when the fire broke out. The major works included the installations of:

* Fire protection to the perimeter steel columns using a boarding system
* Fire protection to the internal steel beams using a spray protection
* A sprinkler system
* A new aluminium cladding system

The refurbishment was carried out floor-by-floor from the lower floors upwards. By the time the fire broke out, the fire protection for all steelwork below the 17th floor had been completed except a proportion of the 9th and 15th floors.

So the floors above 17 had not been retrofitted with fireproofing at the time of the fire.


Note the key difference between the lower floors and the upper floors is the presence of the concrete shear walls.

You can see these walls in this photo. They are the fourth bay in from the corners.



Note that the 9th floor perimeter columns had not been fireproofed, and they buckled.

Do you see the fireproofing on the perimeter columns above and below the 9th floor?



So, based on that information, fireproofing had a HUGE impact on the performance of the building's structural systems in a fire.

Originally posted by Killtown

Slowing through 160 knots with the flaps extended to 25°, the right wing entered a deep stall and the crew lost control of the airplane. The 747 impacted an apartment building in the Bijlmermeer district of Amsterdam at nearly a vertical nose down attitude.

Close, but no cigar.


160 knots is 184 mph.

Also, how many apartment buildings are all steel construction?

Originally posted by Killtown
Yes it's fair. An larger airliner hit a large steel building in Holland and the building only partially collapsed:

Let's look at the building shall we...



Emmmm... And the trade centre again..



Right, I think I can see the problem there, can the folks at home too?


I was ready to comment on the slow speed of the aircraft and the different angle of attack, but looking at that there's not even any point... Did you look at the building before you posted about it?
If that's the level of your reasoning and the standard you use for making comparisons, I'm glad I didn't waste time trawling through your website..

[edit on 18-1-2006 by AgentSmith]

Originally posted by bsbray11
Put into context the amount of damage done before the fires supposedly brought the towers down.

There was less than 15% total column damage in either tower in all likelihood. I say "in all likelihood" because no one went in to examine the core columns, but any common sense would dictate that after the initial impact into the steel perimeter columns, the planes' remains weren't going to have much strength to face the much thicker and wider-spread core columns, of which there were nearly 50 in either building. But the numbers for the perimeter columns were about 11% and 13% severed in the impacted region.

Now, according to NIST's own information regarding the safety ratings of the core and perimeter columns, the buildings would have to have an average of a 75% total column failure on any given floor to cause a whole floor to collapse.

The impacts caused about 15% column failure, so the fires would have to cause over 60% column failure.

Look to ANY steel skyscraper fire, in the history of the world, and show me where any such fire has caused 60% column failure on any given floor!

You are neglecting the role of the floor slabs in providing lateral stability to the columns. Without the floor slabs to pin the columns in place, they are much more susceptible to buckling.

How much more? The critical buckling load is calculated by Euler�s formula.


F = (K*pi^2*E*I) / L^2

F = maximum or critical force (vertical load on column)
E = modulus of elasticity
I = area moment of inertia
L = unsupported length of column


(See the source for an image of the formula.)


The more mathematically inclined among you will have no doubt recognized that as an example of an inverse square law

Thus, if one floor slab failed, the unsupported length of the column will have doubled. This will result in the critical buckling load for those columns to drop by a factor of 4.

If two adjacent floor slabs failed, the unsupported length of the columns will be 3 times the design length and the critical buckling load will be reduced to 1/9th of the design capacity.

Did the floor slabs fail?

Yes. From the initial impact and from the subsequent fires.

If you look at the second plane crashing into the building the majority of it's fuel blew up outside the building.

And other steel framed buildings have burned for days without collapsing.

Something doesn't add up when it comes to the Bush 9/11 explanations.

Originally posted by jinsanity
If you look at the second plane crashing into the building the majority of it's fuel blew up outside the building.

At most, about half of the fuel from the right wing exited the building. The fuel in the left wing hit the core area square on.

Originally posted by jinsanity
And other steel framed buildings have burned for days without collapsing.

Have you even bothered to read the posts in this thread?

Yes, I am aware of the fireproofing issue with that building. As a matter of fact, if you bothered to read my post, you'd see I pointed it out myself before you decided to chime in:

Originally posted by bsbray11
The same source also provides that on and above the 17th floor, fireproofing on the steel was not yet commenced (with the exception of the 18th floor being partially completed). That means no fireproofing at all above the 17th floor for the whole 18 to 20 hours for the fire, which maxed around 800 degrees Celsius.

The fact still remains that bare, naked steel will not lose ANY strength when heated to 250 degrees Celsius. Steel will only lose critical strength when it is heated to 600 degrees Celsius.

And yet what do the tested samples reveal of the heat the WTC steel suffered?

Observations of paint cracking due to thermal expansion. Of the more than 170 areas examined on 16 perimeter column panels, only three columns had evidence that the steel reached temperatures above 250 ºC: east face, floor 98, inner web; east face, floor 92, inner web; and north face, floor 98, floor truss connector. Only two core column specimens had sufficient paint remaining to make such an analysis, and their temperatures did not reach 250 ºC. ... Using metallographic analysis, NIST determined that there was no evidence that any of the samples had reached temperatures above 600 ºC. (p 90/140)

(From the NIST Report - pages indicated).

Oh - wait - did you get that last part?

Using metallographic analysis, NIST determined that there was no evidence that any of the samples had reached temperatures above 600 ºC.

Well then.

If bare naked steel alone could easily take those silly temperatures (and of course it can), then I hardly see the relevance of fireproofing.

You keep bringing it up but you fail to address the fact that the steel simply was not heated to any temperature where fireproofing would even be useful.

Why do you fail to address this, time and again?

Is it that you know of some other test of the physical evidence from Ground Zero, that shows temperatures above the 250 degrees? If so, you might want to call up NIST, 'cause they've been trying to sell their garbage on that point since the start, despite the fact that that very point disproves them itself.

You are neglecting the role of the floor slabs in providing lateral stability to the columns.

And you are neglecting what is called "common sense."

For example (emphasis mine):

Did the floor slabs fail?

Yes. From the initial impact and from the subsequent fires.

This would require the steel to have already failed in the truss holding the concrete up (unless the initial impacts alone were enough to bring the buildings down, but, again, something called "common sense" would dictate that such damage was not enough, as the buildings most certainly did not immediately come down).

So, sorry, but, once again, the steel would still have had to have been heated to a critical temperature.

Any evidence of that? Huh? No? Well, then....



But let's look at what FEMA has said about this anyway. And then I'll repost the problem BillyBob pointed out, which shows how stupid the whole logic here is anyway.

Here's an image taken from the FEMA Report, as provided by the 9/11 Research Site:



In case you haven't noticed, they're telling you that the outer columns both bowed outward and buckled inward, both from heat, but apparently not at the same time.

As pointed out in the FEMA Report with commentary,

The reasons that the authors give only a very cursory explanation (if it can even be called an explanation) is that they are selling you two contradictory features, as part of their "theory" and hoping that you buy both without giving it much thought. In figure 2.20 you are told that the fire caused the steel to expand and push the exterior walls out, however in figure 2.23, you are told that the fire caused the steel to sag and pull the exterior walls inward. Notice that this is exactly how things have been illustrated. In figure 2.20 the wall has been pushed out, in figure 2.23 the wall has been pulled in. So, which is correct? Is the thermal expansion of the beams/trusses accommodated by (axial) expansion, or by sagging?

At relatively low temperatures the beams/trusses expand axially until they buckle. Once they buckle the thermal expansion is accommodated by sagging. This buckling of the beams/trusses is beneficial as it allows the thermal expansion to be accommodated by sagging. The large axial restraint due to the trusses composite action with the concrete and the restraint due to the end columns, means that sagging is the predominant feature. At 500°C (a temperature the slab probably never reached) the 60 foot sections of concrete floor slab between the core and perimeter wall would expand by about 3 inches, however, this extra length was easily accommodated by the sagging of the slab.

Source.

Once again, there is a emphasis on the fact that the temperatures required for all of this were simply not met in the WTC, and thus all of this is impossible anyway, aside from all the contradictions and flawed logic.

Notice that the FEMA Report also apparently exludes certain structural information, specifically 32,000 tons worth of steel, since the WTC Towers each used 96,000 tons. Given that we can draw good info from photographs on the amount of steel used in the perimeter columns, the 32,000 tons of steel that FEMA doesn't account for must either be in the core, or the trusses. Given the theory they're (rather clumsily) trying to sell, I can only imagine where the steel they didn't mention used to go. And again, let me emphasize that our government still has the construction drawings of the WTC classified. We still aren't allowed to look at them.

And the flawed logic that BillyBob brings up in terms of buckling and global collapse:

Originally posted by billybob
if the floors were strong enough to pull the wall in, then the idea that these connections were the lynch pin for the whole tower is ridiculous. especially since the ones that did the alleged pulling were also the first to fail. the magic joist seats simultaneously initiated the collapse by pulling in the whole side of the building, and then the other several thousand completely undamaged, unheated, uncompromised connections managed to offer ZERO RESISTANCE for the rest of the collapse.

So you guys still have all those contradictory theories and contradictory physical evidence and flawed logic and etc. to work through.


And btw,



This image is still the product of fantasy it was when I first called it out to you.

I just hope anyone that comes across this image will have the common sense to ask themselves how anyone could possibly make those GIFs from facts.

We don't even know how much damage to the either core was done by the impacts. No one went in to see. And yet someone has been able to put together those nifty little images for you, Howard, showing exactly how the planes behaved on impact, down to every debris fragment.



[edit on 19-1-2006 by bsbray11]

BSBay, NIST had limited samples to available to determine the temperatures of the steel.

Basic fire science indicates that fire temperatures in excess of 600 C were present. There is no way they could not have been. The steel trusses were the most susceptible to heat, they were the most exposed to the elevated temperatures at the ceilings of the fire floors, and the fireproofing on the trusses was the most susceptible to physical damage.

The FEMA report was a preliminary report. The structural analysis in the NIST report uses more data and better analytical tools.

As for the image of the plane hitting the building, no it is probably not perfectly to scale, and the break up of the wings as they entered the building is at best approximate, but you fail to see the point.

The planes path would have impacted the core areas. The fuel in the left wing would not have exited the building, it would have hit the core area.

The image just helps you visualize this process.