WTC7: Did the fires burn long and hot enough?

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NCSTAR 1-A, page 21:

It is like a joke... They are guessing and in guessing they come up with a political science based conclusion designed to protect those in power... it is as simple as that.

They fully acknowledge that the temperatures are well below the temperatures considered in current practice for determining
fire resistance ratings associated with significant loss of steel strength

But it bothers them not one bit. If it is me that is wrong tell me in plain words how and why I am wrong.

Content from external source:

As the fires progressed, some of the structural steel began to heat. According to the generally accepted test standard, ASTM E-119, one of the criteria for establishing the fire resistance rating for a steel column or floor beam is derived from the time at which, during a standard fire exposure, the average column
temperature
exceeds 538 °C (1000 °F) or the average floor beam temperature exceeds 593 °C (1100 °F).

These are temperatures at which there is significant loss of steel strength and stiffness. Due to the
effectiveness of the SFRM, the highest column temperatures in WTC 7 only reached an estimated 300 °C
(570 °F), and only on the east side of the building did the floor beams reach or exceed about 600 °C

(1100 °F). The heat from these uncontrolled fires caused thermal expansion of the steel beams on the
lower floors of the east side of WTC 7, primarily at or below 400 ºC (750 ºF), damaging the floor framing
on multiple floors.


The initiating local failure that began the probable WTC 7 collapse sequence was the buckling of
Column 79. This buckling arose from a process that occurred at temperatures at or below approximately
400 °C (750 °F), which are well below the temperatures considered in current practice for determining
fire resistance ratings associated with significant loss of steel strength.
When steel (or any other metal) is
heated, it expands. If thermal expansion in steel beams is resisted by columns or other steel members,
forces develop in the structural members that can result in buckling of beams or failures of connections.
 
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NCSTAR 1-A, page 21:

It is like a joke... They are guessing and in guessing they come up with a political science based conclusion designed to protect those in power... it is as simple as that.

They fully acknowledge that the temperatures are well below the temperatures considered in current practice for determining
fire resistance ratings associated with significant loss of steel strength

But it bothers them not one bit. If it is me that is wrong tell me in plain words how and why I am wrong.

Because it was not loss of steel strength that caused the collapse.

It was thermal expansion.
 
Because it was not loss of steel strength that caused the collapse.

It was thermal expansion.
So all these connections broke and stayed broken . . . not just weakened . . . that is the theory? Seems this would be easily recreated . . . using a real connection and heat . . . why not prove it . . . no simulation . . .
 
So all these connections broke and stayed broken . . . not just weakened . . . that is the theory?

Essentially, but it's complicated, there were varying levels of damage. It was the cumulative effect that resulted in a loss of lateral support. Then there was an initiating event that caused the buckling.

See the different damage levels below:



Back to the original point. The 911Research excerpt is claiming that 3.5 hours of heating at 400C. Really all that is needed is for the steel to get to 400C. Once it's at 400C, then it's expanded, and the damage to the connections is done.
 
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Here's an explanation of the damage index (the damage level in the diagram above). Note there's horizontal and vertical damage levels (hence the two diagrams)

A damage index was computed for the horizontal and vertical direction (shear and axial loads) for eachconnection. Failure of fin, knife, and header connections resulted in a loss of support for both horizontal
and vertical directions, whereas, loss of horizontal and vertical support in the seated connections (SWC,
STC, and STP) occurred separately. For example, if all the bolts in a fin connection were sheared, the
connection would be fully damaged (failed with a damage level of 1.0) in both the horizontal and vertical
directions. However, if all the bolts of a seated connection were sheared, the connection would be fully
damaged in the horizontal direction, but not in the vertical direction as the beam or girder would still be
resting on the seat. Failure in the vertical direction would occur when either the member supported by the
connection walked off the seat or the weld at the seat failed.
Content from External Source
 
Here's an explanation of the damage index (the damage level in the diagram above). Note there's horizontal and vertical damage levels (hence the two diagrams)

A damage index was computed for the horizontal and vertical direction (shear and axial loads) for eachconnection. Failure of fin, knife, and header connections resulted in a loss of support for both horizontal
and vertical directions, whereas, loss of horizontal and vertical support in the seated connections (SWC,
STC, and STP) occurred separately. For example, if all the bolts in a fin connection were sheared, the
connection would be fully damaged (failed with a damage level of 1.0) in both the horizontal and vertical
directions. However, if all the bolts of a seated connection were sheared, the connection would be fully
damaged in the horizontal direction, but not in the vertical direction as the beam or girder would still be
resting on the seat. Failure in the vertical direction would occur when either the member supported by the
connection walked off the seat or the weld at the seat failed.
Content from External Source
OK let's prove it . . . as I said these connection can be tested not simulated . . .
 
OK let's prove it . . . as I said these connection can be tested not simulated . . .

That's not the point here George. Read the first two posts again.

The point is that the 911Research excerpt is false. Do you agree that it is false?
 
See above. 400C, about an hour. But actual events are quite complex.

Remember I'm trying to keep this focused on the claims in the first post here. Please look at that again, and my objections to it.
I never considered anything except the NIST Report . . . sorry didn't get the conflict until the last few posts . . . my bad . . . so I can say I understand the NIST Report better . . . as far as an attempt to misrepresent . . . possibly or just a misunderstanding . . . my issue is always simulations are hypothetical . . . show me the real thing . . . ;)
 
Essentially, but it's complicated, there were varying levels of damage. It was the cumulative effect that resulted in a loss of lateral support. Then there was an initiating event that caused the buckling.

See the different damage levels below:


According to this diagram there were 24 connections severed. How they arrive at this is apparently deliberately unclear. Connections are steel and NIST itself states steel is not compromised at these temperatures (well below the temperatures considered in current practice for determining fire resistance ratings associated with significant loss of steel strength)

So NIST infer (although I cannot see exactly where they infer this, myself), thermal expansion at below 400 C applied sufficient force to sever 24 connections as the fire 'traveled around', so it made no difference that the steel subsequently cooled afterwards?

But there has never been a steel framed building brought down by this action either before or since.

On a 60 metre beam, assuming the whole beam attains 400 C you would be looking at approx 384 mm expansion... If that is enough to cause structural failure of the whole building then I suggest there is a serious design fault.

Back to the original point. The 911Research excerpt is claiming that 3.5 hours of heating at 400C. Really all that is needed is for the steel to get to 400C. Once it's at 400C, then it's expanded, and the damage to the connections is done.

And NIST makes this point clearly and unambiguously, where?
 
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I understand this is perhaps a little complicated, and difficult to communicate. But I think it's very importnat to drill down to these fundamental errors. Once you introduce an error into your argument, and then base other things upon it, then it's corrupted your entire argument. And yet the error then becomes so deeply enmeshed in your argument that it's difficult to back away from it.


Critics are deliberately making things difficult. The error of a controlled demolition is the lack of any credible evidence of a controlled demolition, apart from the oft repeated statement that it looks like a demo, which in itself is not true. WTC7 looks like a building collapsing, nothing more.

If a quote from a 9/11 research piece can be used to cast doubt on fire as a cause of the collapse, even if is contradicted by something else, the research report will endlessly be quoted over and over again by the critics, just as "no steel skyscraper ever totally collapsed prior to 9/11." That particular comment means absolutely nothing to the specifics of the 9/11 fires, but gets repeated over and over again as if it was concrete proof of something. The people who keep repeating the comment are not ignorant of the differences between the architecture of the Twin Towers and other steel buildings, nor of a large 767 jetliner plowing into each building, unlike happened in other high rise fires.

50 years after JFK was assassinated, i still read the false comment that the route was changed at the last minute to run past the book Depository. Stemmons Freeway was always the route from Main to the Trade Mart and the only entrance to Stemmons was from Elm Street, not Main. Critics love to point to a map in the local paper which did not show the one block zig zag and point to that as proof the route was changed. That Stemmons Freeway was on the map as the route out of Dealey Plaza was proof the route was not changed.

50 years from 9/11 critics will still be arguing that the Twin Towers could not have fallen the way they did unless it was a controlled demolition. They will still be saying the fires were not hot enough or the Towers fell too fast or that a shower of sparks from one window was evidence of thermate.
 
According to this diagram there were 24 connections severed. How they arrive at this is apparently deliberately unclear. Connections are steel and NIST itself states steel is not compromised at these temperatures (well below the temperatures considered in current practice for determining fire resistance ratings associated with significant loss of steel strength)

They arrive at it through the results of the fire simulation.

So NIST infer (although I cannot see exactly where they infer this, myself), thermal expansion at below 400 C applied sufficient force to sever 24 connections as the fire 'traveled around', so it made no difference that the steel subsequently cooled afterwards?

But there has never been a steel framed building brought down by this action either before or since.

On a 60 meter beam, assuming the whole beam attains 400 C you would be looking at approx 384 mm expansion... If that is enough to cause structural failure of the whole building then I suggest there is a serious design fault.

One beam, maybe, but on multiple beams, on multiple floors, all pushing against basically immovable columns? And consider the key failure connection The Col 79 to Col 44 girder, look at the connection from above, it was a an angle, so an expansion of several inches would break the bolts and push it off its seat.



But again, the point I've been trying to make in this thread is that the 911Research's interpretation is entirely inaccurate. It's claiming that NIST says 3.5 hours of 400C is needed. NIST does not say that.

Thermal expansion with gradual heating is essentially instantaneous. I guess NIST did not spell that out because it's a basic science fact. In fact you can use thermal expansion as a way of measuring how hot something is.

 
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They arrive at it through the results of the fire simulation.



One beam, maybe, but on multiple beams, on multiple floors, all pushing against basically immovable columns? And consider the key failure connection The Col 79 to Col 44 girder, look at the connection from above, it was a an angle, so an expansion of several inches would break the bolts and push it off its seat.





Thermal expansion with gradual heating is essentially instantaneous. I guess NIST did not spell that out because it's a basic science fact. In fact you can use thermal expansion as a way of measuring how hot something is.


Except the dynamics are far more complex and there appears no account taken of thermal sagging in the beams which would compensate for the thermal expansion.

But again, the point I've been trying to make in this thread is that the 911Research's interpretation is entirely inaccurate. It's claiming that NIST says 3.5 hours of 400C is needed. NIST does not say that.

I think regarding that, it is a question of interpretation. NIST's wording is extremely bad and misleading. I think lawyers could argue over it for some time, if it was politically acceptable to do so.
 
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Except the dynamics are far more complex and there appears no account taken of thermal sagging in the beams which would compensate for the thermal expansion.

The beams would only sag at temperatures (over 600C) higher than after they have expanded and done the damage to the connections (400C).

I think regarding that, it is a question of interpretation. NIST's wording is extremely bad and misleading. I think lawyers could argue over it for some time, if it was politically acceptable to do so.

I'm sure if you go through a thousand pages of reports you will always be able to find some poorly worded language. But the point here is that the 911Research excerpt is clearly dead wrong.
 
One thing to consider is that even if the fire moved from one area to another, the beam was already hot. The fire would continue to keep it hot.
 
The beams would only sag at temperatures (over 600C) higher than after they have expanded and done the damage to the connections (400C).

http://books.google.co.uk/books?id=...&sa=X&ei=PvOGUZf6MciCOLemgdAN&ved=0CD8Q6AEwAA

Fundamentals of Fire Fighter Skills - Page 169

A steel beam exposed to a fire will stretch (elongate) ; if it is restrained so that it cannot elongate, it will sag, warp, or twist.
Content from External Source
Admittedly this is a 2003 paper but it offers an interesting viewpoint.
http://www.era.lib.ed.ac.uk/handle/1842/1216

A number of different explanations of how and why the Towers collapsed have appeared since the event. None of these however have adequately focused on the most important issue, namely ‘what structural mechanisms led to the state which triggered the collapse’. Also, quite predictably, there are significant and fundamental differences in the explanations of the WTC collapses on offer so far. A complete consensus on any detailed explanation of the definitive causes and mechanisms of the collapse of these structures is well nigh impossible given the enormous uncertainties in key data (nature of the fires, damage to fire protection, heat transfer to structural members and nature and extent of structural damage for instance)

The results are illuminating and show that the structural system adopted for the Twin-Towers may have been unusually vulnerable to a major fire. The analysis results show a simple but unmistakable collapse mechanism that owes as much (or more) to the geometric thermal expansion effects as it does to the material effects of loss of strength and stiffness. The collapse mechanism discovered is a simple stability failure directly related to the effect of heating (fire). Additionally, the mechanism is not dependent upon failure of structural connections.
Content from External Source
http://www.sciencedaily.com/releases/2011/09/110902133055.htm

Wellman led a portion of the work focusing on the effects of fire on a building's steel-and-concrete floor and its connections to the building. The composite design is the most common type of floor system used in steel structures.
Content from External Source
Would you agree, if they are seeking to find out how the connections perform after extreme heat... that logically means the connections have not failed previously due to thermal expansion?
The aim of the research is to learn precisely what happens to the connections between a floor's steel beams and the building columns. Extreme heat causes the beams to sag. "When it starts sagging, the question is, how do the connections perform? This has been a big question for the industry," Varma said. The researchers analyzed critical joints after a floor system was subjected to extreme heat in a special oven at Michigan State University. Results will be used to help researchers create a model of the steel-concrete floor system

Content from External Source
I realise this is off topic but I include it because it demonstrates the bona fide expertise in this field as well as the 'thinking' of these engineers. This is supposed to reassure people of the safety of new nuclear power stations... it doesn't reassure me. They are dealing with incredible temperatures and claiming safety when 'conventional wisdom' (post 9/11) poses thermal loss of integrity in steel and concrete in very short time at low temperature in both as 'highly likely'.

Varma also has led research to test a new type of design for nuclear power plants. The work focuses on testing structures like those to be used in the Westinghouse Electric Co. AP1000 standard nuclear power plant design. Engineers tested components of an "enhanced shield building" that will contain the plant's main system components.

The building consists of an inner steel-wall containment vessel and an outer radiation shield made using a technology called steel-concrete-composite construction. Instead of using more conventional reinforced concrete, which is strengthened with steel bars, the steel-concrete approach uses a sandwich of steel plates filled with concrete.

Content from External Source
And then we have the effects of fire on concrete... not very resilient

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

Due to its low thermal conductivity, a layer of concrete is frequently used for fireproofing of steel structures. However, concrete itself may be damaged by fire. An example of this was the 1996 Chunnel fire, where the fire reduced the thickness of concrete in an undersea tunnel connecting France with England. For this reason, common fire testing standards, such as ASTM E119, do not permit fire testing of cementitious products unless the relative humidity inside the cementitious product is at or below 75%. Otherwise, concrete can be subject to significant spalling.

Up to about 300 °C, the concrete undergoes normal thermal expansion. Above that temperature, shrinkage occurs due to water loss; however, the aggregate continues expanding, which causes internal stresses. Up to about 500 °C, the major structural changes are carbonatation and coarsening of pores. At 573 °C, quartz undergoes rapid expansion due to phase transition, and at 900 °C calcite starts shrinking due to decomposition. At 450-550 °C the cement hydrate decomposes, yielding calcium oxide. Calcium carbonate decomposes at about 600 °C. Rehydration of the calcium oxide on cooling of the structure causes expansion, which can cause damage to material which withstood fire without falling apart. Concrete in buildings that experienced a fire and were left standing for several years shows extensive degree of carbonatation from carbon dioxide which is reabsorbed.
Concrete exposed to up to 100 °C is normally considered as healthy. The parts of a concrete structure that is exposed to temperatures above approximately 300 °C (dependent of water/cement ratio) will most likely get a pink color. Over approximately 600 °C the concrete will turn light grey, and over approximately 1000 °C it turns yellow-brown.[4] One rule of thumb is to consider all pink colored concrete as damaged that should be removed.
Fire will expose the concrete to gases and liquids that can be harmful to the concrete, among other salts and acids that occur when gases produced by a fire come into contact with water.
If concrete is exposed to very high temperatures very rapidly, explosive spalling of the concrete can result. In a very hot, very quick fire the water inside the concrete will boil before it evaporates. The steam inside the concrete exerts expansive pressure and can initiate and forcibly expel a spall.[5]

Content from External Source
 
I have included following for comparison/context purposes.

http://www.aisc.org/DynamicTaxonomyFAQs.aspx?id=1996

[h=2]11.3.2. At what temperature does a typical fire burn?[/h] The duration and the maximum temperature of a fire in a building compartment depends on several factors including the amount and configuration of available combustibles, ventilation conditions, properties of the compartment enclosure, weather conditions, etc. In common circumstances, the maximum temperature of a fully developed building fire will rarely exceed 1800°F. (982 C). The average gas temperature in a fully developed fire is not likely to reach 1500°F.(816 C). Temperatures of fires that have not developed to post-flashover stage will not exceed 1000°F.(538 C)
Content from External Source
http://www.workingfire.net/misc3.htm

Flashover! It is the most dangerous time of a fire. When the room bursts into flame, flashover has occurred. The scientific definition of flashover states it is caused by the radiation feedback of heat. Heat from the growing fire is absorbed into the upper walls and contents of the room, heating up the combustible gases and furnishings to their auto-ignition temperature.

Content from External Source
 
I have included following for comparison/context purposes.

http://www.aisc.org/DynamicTaxonomyFAQs.aspx?id=1996

11.3.2. At what temperature does a typical fire burn?

The duration and the maximum temperature of a fire in a building compartment depends on several factors including the amount and configuration of available combustibles, ventilation conditions, properties of the compartment enclosure, weather conditions, etc. In common circumstances, the maximum temperature of a fully developed building fire will rarely exceed 1800°F. (982 C). The average gas temperature in a fully developed fire is not likely to reach 1500°F.(816 C). Temperatures of fires that have not developed to post-flashover stage will not exceed 1000°F.(538 C)
Content from External Source
http://www.workingfire.net/misc3.htm

Flashover! It is the most dangerous time of a fire. When the room bursts into flame, flashover has occurred. The scientific definition of flashover states it is caused by the radiation feedback of heat. Heat from the growing fire is absorbed into the upper walls and contents of the room, heating up the combustible gases and furnishings to their auto-ignition temperature.

Content from External Source
So Oxy . . . can you summarize your point . . . seems you think the connections would or would not fail? . . . instead the beams would sag or twist . . .? While Mick thinks they (beams) were not hot enough to sag or twist . . . seems the answer is in the connections . . . so NIST has to have the connections fail before the beams sag . . . how can you simulate that? As I have said over and over . . . This needs to be tested with the real materials . . . !!!!!!
 
So Oxy . . . can you summarize your point . . . seems you think the connections would or would not fail? . . . instead the beams would sag or twist . . .? While Mick thinks they (beams) were not hot enough to sag or twist . . . seems the answer is in the connections . . . so NIST has to have the connections fail before the beams sag . . . how can you simulate that? As I have said over and over . . . This needs to be tested with the real materials . . . !!!!!!

I don't know if they were hot enough to sag and twist. I suspect some were. The point was more that they would expand first, and what happened after they had expanded would be mostly irrelevant in this case, as the damage would be done.
 
Would you agree, if they are seeking to find out how the connections perform after extreme heat... that logically means the connections have not failed previously due to thermal expansion?

Yes, but I think that was in reference to WTC1&2 - rather different structures.

Different building respond differently. in WTC1&2 the floor trusses first expanded, and then sagged. The sagging ultimately pulled in the outer columns (as seen on video).

And some of the WTC7 spans undoubtably DID sag.
 
I don't know if they were hot enough to sag and twist. I suspect some were. The point was more that they would expand first, and what happened after they had expanded would be mostly irrelevant in this case, as the damage would be done.

Research indicates otherwise.

Fundamentals of Fire Fighter Skills - Page 169

Content from external source:

A steel beam exposed to a fire will stretch (elongate) ; if it is restrained so that it cannot elongate, it will sag, warp, or twist.

Content from external source:

The aim of the research is to learn precisely what happens to the connections between a floor's steel beams and the building columns. Extreme heat causes the beams to sag. "When it starts sagging, the question is, how do the connections perform? This has been a big question for the industry," Varma said. The researchers analyzed critical joints after a floor system was subjected to extreme heat in a special oven at Michigan State University. Results will be used to help researchers create a model of the steel-concrete floor system

These are impeccable sources and I suggest the only deduction possible is that, it would be 'entirely unusual', (unheard of?), that significant thermal expansion acts independently as a precursor to sagging/warping.

Undoubtedly 7's slender long beams were firmly secured at each end,(save for isolated impact damage areas), which means most (inc 79) cannot elongate. Thus thermal expansion cannot act purely as a ram

Instead they will sag, warp, or twist
which would automatically impact favourably on the survival time of the connections and would preclude easy 'forcing of beams, off of support connections.

That logically means the connections have not failed previously due to thermal expansion, as previously inferred in the thread.

Logically, either NIST is incorrect or has been mis interpreted.

These findings are not specific to any building but are the well established and researched principles used in design and construction of all steel and concrete mid to high rise office blocks, inc wtc's 1,2 and 7.

Cairenn, I do not see the relevance of your question but yes I have worked cutting steel with oxy-acetelene but that is not the issue. The issue here is one of research and the application of pure logic.
 
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I asked because it seems that many have a limited understanding of how metal responds to heat. Not only have I worked silver, copper and brass, I have also worked iron in a coal fired forge. I have also made my own tools where I had to soften, then harden then temper the steel.

When the beams expand, I can see them pushing out the facade. That would explain the bulge that the firefighters noticed, nothing else does, says logic.
 
I asked because it seems that many have a limited understanding of how metal responds to heat. Not only have I worked silver, copper and brass, I have also worked iron in a coal fired forge. I have also made my own tools where I had to soften, then harden then temper the steel.

When the beams expand, I can see them pushing out the facade. That would explain the bulge that the firefighters noticed, nothing else does, says logic.

But extensive research says that sagging and twisting is an integral factor in the equation. So far I have not seen this issue addressed in the NIST report, which appears to be an extremely serious ommision and flaw.
 
I don't know if they were hot enough to sag and twist. I suspect some were. The point was more that they would expand first, and what happened after they had expanded would be mostly irrelevant in this case, as the damage would be done.
Would not the connections become more pliable and expand with heat as well and tend to maintain their integrity . . . .?
 
Would not the connections become more pliable and expand with heat as well and tend to maintain their integrity . . . .?

Perhaps if the entire building was suspended in space, composed of one material, and heated evenly at every point, yes.

But you have individual beams pushing against much stronger (and much cooler) columns that are anchored in place by the beams (and more importantly the rigid concrete slab) in the floors above and below.

Something has to give. As Oxy points out this can lead to the beam itself bending. However in order to do that it has to put sufficient force on the connection to bend the beam. That amount of force is not what the connection was designed to withstand, so it can fail. In some cases the beams are not at right angles to the column.

This is all in the report. Example:

8.7.5 Seats Used for Floor System Connections

Floor beams and girders that framed into exterior columns, and in some instances, girders that framed into
interior columns, had seated connections. For example, the girder that framed between interior Column
79 and exterior Column 44 had such connections at both ends.

Seat connections to exterior columns where the floor beam framing was perpendicular to the exterior
moment frame were as shown in Figure 8–20. Where the floor beam framed into an exterior column at a
skew angle, the seat angle was replaced by a plate. Figure 8–21 shows the seat connection at Column 79
that supported the girder spanning to Column 44 on the exterior. The details of the connections of the
other two girders that framed into Column 79 are not shown.



In a seated connection, the beam or girder was supported by the seat, which was welded to the column.
Bolts were installed that fasten the beam or girder to the seat for erection purposes. These erection bolts
did not carry any gravity load; rather, they were installed to insure that the beam or girder was held in
place during erection. NIST found no evidence that the girders or beams in WTC 7 were welded to the
seats. In a similar way, an angle or plate was bolted to the top flange to prevent the beam or girder from
twisting, but there was little restraint to bending in the plane of the beam.


Consider the girder that spanned between Column 79 on the interior of the building and Column 44 on the
exterior. Thermal expansion of this girder would have loaded the erection bolts in shear, since (1) there
were no shear studs anchoring the girder to the slab (and thereby restraining elongation), and (2) the
columns were prevented from lateral movement because they were embedded in the floor slabs which had
considerable in-plane stiffness. Additionally, the expansion of floor beams that framed into this girder,
because the framing was asymmetrical, tended to add additional shear load to the erection bolts. The
combination of these two shear loads could have failed the bolts in shear. If the erection bolts were to
fail, then there would be no positive attachment preventing the girder from being pushed off the seat.
Content from External Source
Look at the diagram in conjunction with the text there. Especially the top down view (Section A-A in fig 8-21) which shows the angle.

Note also that the only thing holding the girder on the plate was the erection bolts, which were not designed to take any structural load.

Girder expands, bolts break, end of the girder gets pushed off the seat.

This is just one mode of failure, but a key one. Other connections would fail in different ways.

And tying this all back to the original point - all that is needed for this particular failure is the heating of the beam up to 400C. Once it's at 400C it's either bent, or the bolts are broken, and the end of the girder has been pushed off the seat. If does not require 3.5 hours at 400C, as 911 research claims. It does not even require the connection itself to be heated.
 
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I have quite a bit to say about this thread but for the moment, I would pose these few questions.

Bearing in mind the red highlited...How does NIST validate the boldened statement below... Do they have the beams, girders, connections... are there photos of same.

Do 7's plans call for welding of beams to seats... if not why not

Do nist provide dimensions for seats and plates....

In a seated connection, the beam or girder was supported by the seat, which was welded to the column.
Bolts were installed that fasten the beam or girder to the seat for erection purposes. These erection bolts
did not carry any gravity load; rather, they were installed to insure that the beam or girder was held in
place during erection. NIST found no evidence that the girders or beams in WTC 7 were welded to the
seats.
In a similar way, an angle or plate was bolted to the top flange to prevent the beam or girder from
twisting, but there was little restraint to bending in the plane of the beam.
 
Maybe they have the building specifications? Where there is no mention of welding them in place? Welding is not always a good idea, because it makes a rigid structure, instead of a slightly flexible one. Buildings need some flexibility.

I once managed to stake a pavilion down in such a way, that when it collected water in a rain, instead of a small area collapsing, the entire 10 x20 ft frame buckled and fell, There were 6 uprights and 16 poles in the roof, not a single one was not damaged.
 
I have quite a bit to say about this thread but for the moment, I would pose these few questions.

Bearing in mind the red highlited...How does NIST validate the boldened statement below... Do they have the beams, girders, connections... are there photos of same.

Do 7's plans call for welding of beams to seats... if not why not

Do nist provide dimensions for seats and plates....

The diagrams say "based on fabrication shop drawing", and then I suppose the "found no evidence" bit means that they found no indication that the girder would be welded. I think they discuss it more in the report.
 
The diagrams say "based on fabrication shop drawing", and then I suppose the "found no evidence" bit means that they found no indication that the girder would be welded. I think they discuss it more in the report.

I am researching some of NIST's previous (and contradictory) reports but it would be helpful if you can come up with any leads on this, (from your cia computer :)), especially any physical test results that they may have undertaken.

Also I would like to try to clarify why there was 'no evidence' that the connections were welded. If there was 'no evidence', it appears something of a leap to conclude they were not. Also any dimensions of the support plates would be interesting to work out how much movement would be necessary to unseat the beams would also be helpful.

I am a bit pushed for time at the mo so you will likely have some respite from me for awhile :)... Enjoy it while it lasts lol.
 
I'm a bit pushed myself. I think the diagrams above are to scale though, so you should be able to figure it out from some measurement in the NCSTAR 1-9

And I assume it's probably just from standard practice not to weld seated joins if they are not indicated in the shop drawings.

You should read about seated vs. shear vs. moment connections. Interesting stuff.
 
The following link is a pdf which sets out the scientific case describing the fatal 'errors' and contradictions in NIST's reports.

http://www2.ae911truth.org/downloads/Ryan_Hartford_2.pdf

Eye opening stuff...

And more here:

http://911truth.org/article.php?story=20080911073516447

Interesting that on page 46 of ae911 pdf, it states;
The evidence shows that fires were first appeared on the south side of

floors 11 through 13after 2 pm and the fire on the NE corner of floor 12

was out at 3:49(and all floor 12 fires were out at 4:45) was out at 3:49

(and all floor 12 fires were out at 4:45)

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Especially when you consider that evacuations were happening 12 to 1pm, due to expected collapse of 7

Happy debunking :)
 
Once steel has been heated to the point it softens, it's structure changes. Rapid cooling can then make it brittle.

I have made tools from steel blanks, and you have to soften the steel so you shape it, then harden it to it doesn't easily deform, then you have to temper it, because the hard version is brittle and will break easily.

It is quite possible, to me, that the heat softened the steel. That softening did not go away when the heat did. In some areas, where they tried to fight the fire, some rapid cooling could have occurred, making that steel brittle.
 
Once steel has been heated to the point it softens, it's structure changes. Rapid cooling can then make it brittle.

I have made tools from steel blanks, and you have to soften the steel so you shape it, then harden it to it doesn't easily deform, then you have to temper it, because the hard version is brittle and will break easily.

It is quite possible, to me, that the heat softened the steel. That softening did not go away when the heat did. In some areas, where they tried to fight the fire, some rapid cooling could have occurred, making that steel brittle.
Anything is possible . . . as everyone likes to say . . . :)
Except there was no water to fight the fires on the floors in question and the firefighters had been "Pulled."
 
If the steel got to the softening temperature, then it stayed soft and deformable.

One of the reasons that 'Damascus' sword blades where valued, was their combination of hard steel that will hold an edge well and softer steel that doesn't break easily. There were some Viking blades that were braided from hard and softer steel. Most sword blades in medieval Europe were not good at cutting, most of the damage they did was from crushing. Japanese blades however, were able to be sharp and flexible.
 
Overview... What is comparable or classified as a 'Major Event

http://www.routledge.com/books/details/9780415557337/

Major events—notably the Broadgate fire in London, New York’s World Trade Center collapse, and the Windsor Tower fire in Madrid—as well as the enlightening studies at the Cardington fire research project have given international prominence to performance-based structural fire engineering. As a result, structural fire engineering has increasingly attracted the interest not only of fire and structural engineers but also of researchers and students
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So whilst recognising there are differences... it seems pretty clear that these events are not 'apples and oranges' or 'grapes and watermelons' but are indeed highly comparable on many levels.

The Cardigan Fire Tests

http://911research.wtc7.net/mirrors/guardian2/fire/SCI.htm
3 THE CARDINGTON FIRE TESTS

3.1 Research programme

In September 1996, a programme of fire tests was completed in the UK at the Building Research Establishment's Cardington Laboratory.
The tests were carried out on an eight-storey composite steel-framed building that had been designed and constructed as a typical multi-storey office building. The purpose of the tests was to investigate the behaviour of a real structure under real fire conditions and to collect data that would allow computer programs for the analysis of structures in fire to be verified.
Content from External Source
Some results from the Cardigan and Broadgate Fire Tests

http://911research.wtc7.net/mirrors/guardian2/fire/cardington.htm

4.2.2 Churchill Plaza building, Basingstoke

In 1991 a fire took hold in the Mercantile Credit Insurance building in Basingstoke. [197] The twelve storey high building was constructed in 1988 and was of composite steel and concrete construction. The columns and the composite floor beams had applied fire protection but the soffit of the floor slab was unprotected. The fire rating of the building was 90 minutes.

The fire started on the 8th floor and spread to the tenth floor
as external glazing failed. The protection materials performed well and there was no permanent deformation of the steel frame or damage to the protected connections. Similar to Broadgate the metal deck showed signs of debonding from the concrete floor slab probably due to the steam from the concrete. Load tests on the most damaged parts of the slab showed it had adequate strength to be used unrepaired. No structural repair was required on the protected steel. The cost of repair to the building was �5 million but most of this was repairing smoke damage.
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Windsor Torre Building in Madrid in February 2005

http://www.newsteelconstruction.com/wp/steel-in-fire-the-latest-news/?print=1


View of Madrid fire from the East side. This appears to show that part of the floor had collapsed internally although the perimeter columns are still intact at this stage

The performance of steel in fire has been proven through comprehensive tests worldwide. In the first of a series of fire engineering articles John Dowling of Corus Construction and Industrial assesses the impact of recent real life events on our knowledge of how steel behaves in fire.

Two recent events have focused attention on the performance of steel structures in fire.
The first of these is the publication of the draft official report from the National Institute of Standards and Technology (NIST) in the United States into the collapse of the World Trade Centre towers in September 2001; and the second is a fire at the Windsor Torre Building in Madrid in February 2005. Both events have excited considerable comment, in the latter case, a great deal of it speculative.

The official NIST report is the latest in a wide ranging series from that organisation and pulls together thirty recommendations on changes to existing practice and future research. The report pulls no punches in laying the blame for the collapses. The executive summary states that: “The WTC towers likely would not have collapsed under the combined effects of aircraft impact damage and extensive multifloor fires if the thermal insulation had not been widely dislodged by impact.” This had been suspected for some time and supports an opinion previously expressed by NIST in their building performance report, that: “The structural damage sustained by each of the two buildings as a result of the terrorist attacks was massive. The fact that the structures were able to sustain this level of damage and remain standing for an extended period of time is remarkable, and is the reason that most of the building’s occupants were able to evacuate safely.
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Now such a statement naturally inspires the question of, 'If this is the case why was 7 expected to fall, even before major fires were observed', and 'Why did it actually fall in such a spectacular fashion, resembling a demolition' when even NIST admit "while debris impact from the collapse of WTC 1 initiated fires in WTC 7, the resulting structural damage had little effect in causing the collapse of WTC 7."

It is acknowledged and documented that the SFRM (fire protection), was in excellent condition and undamaged (bar small areas directly around impact damage) and well exceeded specifications.
 
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If the steel got to the softening temperature, then it stayed soft and deformable.

One of the reasons that 'Damascus' sword blades where valued, was their combination of hard steel that will hold an edge well and softer steel that doesn't break easily. There were some Viking blades that were braided from hard and softer steel. Most sword blades in medieval Europe were not good at cutting, most of the damage they did was from crushing. Japanese blades however, were able to be sharp and flexible.
Analogies are nice but a sword blade is not a high rise office building . . .
 
Analogies are nice but a sword blade is not a high rise office building . . .

Exactly, lets try to keep it on topic. "Did the fires burn long and hot enough"

Well not according to the above and not according to this:

http://whatreallyhappened.com/WRHARTICLES/spain_fire_9-11.html

As an intense fire consumed the 32-story Windsor Building in Madrid's
business district, the press reports all began with the words "fear
of collapse." After 24 hours, however, the tower, which was a similar
construction to the twin towers of the World Trade Center, remained
standing.


The fact that an extremely severe fire did not cause the Spanish
steel and concrete tower to collapse raises serious questions about
the events of 9/11 and how they have been explained. Why did the
Windsor Building remain standing when similar towers in New York City
collapsed completely after being affected by much less intense fires
burning for considerably shorter periods of time?


The Windsor Building fire in Madrid provides an excellent real-world
model to show how the twin towers should have responded to "an
extremely severe fire" alone. The Windsor Building has central
support columns in its core section, which is similar to the
construction of the twin towers. This central core is what supported
the gravity load of the towers.


In the Windsor Building fire, the fire is thought to have started on
the 21st floor late on Saturday night, Feb. 12. The upper floors were
consumed by intense fire for at least 18 hours. The fire moved down
the building and burned the entire structure. The fire is reported to
have burned temperatures of at 800 degrees Celsius, or nearly 1,500
degrees Fahrenheit.


There was a partial collapse of parts of the top 10 floors as the
trusses, which went from the core columns to the outside walls,
appear to have failed
. It is important to note, however, that the
lower floors did not collapse and the core section is still standing
with a construction crane on the roof.


Two of the contractors who removed the rubble told AFP that they had
found molten steel in the 7th basement level
when they reached the
bedrock where the columns were based. There is no explanation for
what caused such intense residual heat to be found at the base of the
twin towers, although some experts have pointed to powerful
explosives
.
Content from External Source
 
Exactly, lets try to keep it on topic. "Did the fires burn long and hot enough"

Well not according to the above and not according to this:


In the Windsor Building fire, the fire is thought to have started on
the 21st floor late on Saturday night, Feb. 12. The upper floors were
consumed by intense fire for at least 18 hours. The fire moved down
the building and burned the entire structure. The fire is reported to
have burned temperatures of at 800 degrees Celsius, or nearly 1,500
degrees Fahrenheit.


There was a partial collapse of parts of the top 10 floors as the
trusses, which went from the core columns to the outside walls,
appear to have failed
. It is important to note, however, that the
lower floors did not collapse and the core section is still standing
with a construction crane on the roof.


I thinks its funny that you point to the Windsor fire as somehow evidence for your argument. Indeed the your quote is misleading to say the least. The FACTS are that fire in the Windsor DID cause an almost complete collapse of several floors...and this fire induced collapse took place after only 2.5hrs of burning. It was the design of the building that prevented further collapse

Despite a complete burn-out, the strength provided by a technical concrete floor, plus the passive fire resistance of the building's concrete core and frame, prevented the building from collapse.

The only part of the building to collapse was the network of steel perimeter columns supporting the slab on the upper floors.
Content from External Source
http://www.concretecentre.com/online_services/case_studies/windsor_building,_madrid.aspx

A large portion of the floor slabs above the 17th Floor progressively collapsed during the fire when the unprotected steel perimeter columns on the upper levels buckled and collapsed (see Figure 1). It was believed that the massive transfer structure at the 17th Floor level resisted further collapse of the building.
Content from External Source
http://www.mace.manchester.ac.uk/pr...Study/HistoricFires/BuildingFires/default.htm


Clearly, this fires demonstrates that fire can cause structural failure of steel columns in a relatively short amount of time.
 
I thinks its funny that you point to the Windsor fire as somehow evidence for your argument. Indeed the your quote is misleading to say the least. The FACTS are that fire in the Windsor DID cause an almost complete collapse of several floors...and this fire induced collapse took place after only 2.5hrs of burning. It was the design of the building that prevented further collapse

Despite a complete burn-out, the strength provided by a technical concrete floor, plus the passive fire resistance of the building's concrete core and frame, prevented the building from collapse.

The only part of the building to collapse was the network of steel perimeter columns supporting the slab on the upper floors.
Content from External Source
http://www.concretecentre.com/online_services/case_studies/windsor_building,_madrid.aspx

A large portion of the floor slabs above the 17th Floor progressively collapsed during the fire when the unprotected steel perimeter columns on the upper levels buckled and collapsed (see Figure 1). It was believed that the massive transfer structure at the 17th Floor level resisted further collapse of the building.
Content from External Source
http://www.mace.manchester.ac.uk/pr...Study/HistoricFires/BuildingFires/default.htm

Clearly, this fires demonstrates that fire can cause structural failure of steel columns in a relatively short amount of time.


Thanks SR, Good repost. Seems it is nowhere near as cut and dried as that though. The steel was not like the WTC giant steel columns with very good fire protection... they were very lightweight which is vulnerable to fire but on top of that it had no SFRM on the floors which collapsed, (Which is still a partial collapse of the whole).

So in short we have
Building being renovated
Unprotected (NO Fireproofing on collapse areas) and very lightweight steel.
Raging inferno for 18 hours.
Steel crane sat on roof, (structurally undamaged)

Then we have

Below floor 17 the lightweight steel was protected by fireproofing (SFRM), which is an extremely important factor in why even the lightweight steel did not collapse in these areas.

I highly recommend reading the whole report as I have left out lots of interesting info to keep it short.

http://www.newsteelconstruction.com/wp/lessons-from-madrid/?print=1

A view has previously been expressed that the collapses were caused by failure of perimeter steel mullion columns which were directly exposed to fire and this has been contrasted unfavourably with the perception that the concrete structure performed extraordinarily well.

Now that a report has been published by the Spanish authorities(1) it is possible to see that the situation is not as simple as the view expressed above. This article reviews some the information contained in this report and develops one important hypothesis.
First it must be made absolutely clear that the steel mullion columns should have had applied fire protection. Reference to BS 5950-8(2) or the Eurocodes would confirm this as they were relatively light load bearing multi-storey columns with high section factors (A/V between 100 and 200 m-¹​).

In the course of refurbishment, fire protection had already been applied to these mullion columns on all levels below the 17th with the exception of the 9th. None of the fire protected mullions failed and the Spanish report concludes that, although it cannot be stated with absolute certainty, the collapse of the upper storeys would not have occurred had this fire protection already been in place throughout.

That is the end of the report’s specific conclusions about the contribution of the steel mullions to the collapse. If you do not protect light steel members they will fail in a prolonged fire. Hardly rocket science!

However, it is interesting to see what happened on the 9th level. The picture shows that the unprotected steel mullions buckled as they were restrained against thermal expansion. But collapse did not ensue. Why? The answer is that the loads were taken by multiple alternative load paths – a classic robustness provision. Mullions above from level 10 to 17 and below from level 8 down were able to distribute and share the loads as the 9th level mullions failed. The fact that there were 60 mullions per floor level added to the number of alternative load paths available.
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Jazzy, please take note of above.

Why was it that although these alternative load paths existed above the 17th level they did not apparently prevent the collapses?

There are two answers to this – firstly because there was no effective fire compartmentation of the building; secondly because of the failure of two internal concrete columns. Yes, a portalised pair of 1200 x 500 concrete columns did collapse.

The fire started on the 21st floor level. As shown in the picture taken from the east after the fire, the serviced storey between 16th and 17th levels arrested all the progressive collapse that occurred to the upper superstructure. Such “strong floors” in multi-storey buildings are another classic robustness provision.
Content from External Source
NB.. Classic means, old, well known, tried and tested. And yes The WTC's had them.


The fire eventually raged over nearly every floor from the 5th upwards. It spread both up and down the building as there was no effective fire stopping between floor levels which were meant to act as compartment boundaries. This seems to be due to the fact that the fire stops had been removed during the refurbishment process. Yet many levels of the building were still in daily use – luckily the fire occurred at night! As should be well known, the need for proper fire protection measures starts during construction and does not cease during refurbishment. Lack of effective compartmentation is a classic weakness in fire.

Had each floor provided effective fire compartmentation then even unprotected mullions on floors above and below would have retained their capacity to redistribute loads as occurred around the 9th level. Compartmentation is, in effect, providing fire protection to all parts of the structure outside that where the fire originates, and, as insurers will say, compartmentation is a key to limiting the scale of damage from a fire.

Content from External Source
And they should know

So in short, 7 was

better fireproofed,

had stronger columns

although open plan flooring, 7 was infinitely better compartmentalised between floors.

much smaller fires (which moved every 20mins or so)

burned for very short times

collapsed spectacularly in a few seconds

straight down, like a demolition. (not bits falling off here and there and then half hour later another bit falling off, even the odd floor collapsing or a section... no straight down in seconds... gone!).
 
So in short we have
Building being renovated
Unprotected (NO Fireproofing on collapse areas) and very lightweight steel.
Raging inferno for 18 hours.
Steel crane sat on roof, (structurally undamaged)


So, in short- you have structural steel failure and collapse after only 2.5 hrs of burning.

and the design of of the building ie; concrete core and frame and "strong" floors prevented further collapse.

thanks Oxy.
 
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