Total Building Collapse from a Single Column Failure

[pgimeno]

How do the beams stay in contact with the girder if their connections are broken? These were fin connections where the clamp is from the side. There was no bottom seat, so if the connection is broken the beams would fall.

You also have not answered my question as to what forces would have caused the beam to girder connections to break as the areas of the NIST WTC 7 report you quote claims. Unfortunately for you the report doesn't say, but you need to answer if you support what they say.

How do the beams stay in contact with the girder if their connections are broken? These were fin connections where the bolts are from the side. There was no bottom seat, so if the connections are broken the beams would fall.

You also have not answered the question as to how the forces were generated that are alleged to have caused the beam to girder connections to break as the NIST WTC 7 report (that you quote) claims. Unfortunately for you, the report doesn't say, but you need to answer if you support what they say.

It seems we have a case of wanting it both ways here. First, the claim that the beams pushed the girder because it was unrestrained (it is said that it did not have shear studs), and next we are being told that the beam to girder connections were broken due to thermal expansion. However, that would require the girder being able to restrain the beams, which in the first instance we are told it can't.

I'll respond when the time to allow you to edit has expired.

 

[pgimeno]

So we can assume that your proposed new FEA containing the effects of the 'left out' structural elements will also include every other nearby element and the effect on each by the , changing, fire environment. It will be a fully faithful model of the two or three floors involved, correct?

One wonders on the supercomputer time required for this run and if more than one run would be done in order to bracket certain variables such as fire gas temps, air supply, and fire duration in specific areas.

Will such a FEA simulation cover all possible ways in which SFRM may have spalled from the elements due to the movements?

It's not like it hasn't happened in past.

As far as I know, that factor was ignored by NIST.

 

[Tony Szamboti]

I'll respond when the time to allow you to edit has expired.

The last comment which I added was not part of the questions. It just pointed out the contradictory nature of what you are supporting. I made those changes within a couple of minutes, so you must be sitting at your computer just waiting. That seems sort of odd, but who am I to say.

I won't be making any additions to the questions I asked you, so can we have your response?

 

[pgimeno]

How do the beams stay in contact with the girder if their connections are broken? These were fin connections where the bolts are from the side. There was no bottom seat, so if the connections are broken the beams would fall.

I've issues with that.

1) The NIST report states 75-99% damage. That means that not necessarily all bolts were broken. If one bolt remains, the beam is still in place and the girder can easily pivot on it and roll (off).

2) If all bolts failed, the beam would fall to the girder's flange at most. If the connection plates were not too damaged, they would still hold the beam in position horizontally.

You also have not answered the question as to how the forces were generated that are alleged to have caused the beam to girder connections to break as the NIST WTC 7 report (that you quote) claims. Unfortunately for you, the report doesn't say, but you need to answer if you support what they say.

I've even quoted the pertinent part. Go look. And that question was not your initial question, by the way.

It seems we have a case of wanting it both ways here. First, the claim that the beams pushed the girder because it was unrestrained (it is said that it did not have shear studs), and next we are being told that the beam to girder connections were broken due to thermal expansion. However, that would require the girder being able to restrain the beams, which in the first instance we are told it can't.

Well, for one thing, there was a beam on the other side too. The girder was not completely free to move west. That connection was less damaged.

Also, if the beams expanded at different times, one could push while the others held the girder. Of course this possibility means at least one or two would remain in good shape in the end, so ultimately the answer is in NIST's FEA.

But you're contending that their FEA produced the failures they state, on the sole basis that they "omitted structural features" on an unrelated part of the structure. That's reaching.

And you still haven't even begun to address Newton's Bit argument that the connections wouldn't resist the moment anyway, even in their pristine state, I assume.

 

[tfk]

"Our study has identified thermal expansion as a new phenomenon that can cause the collapse of a structure." ~ Shyam Sunder Aug 21st 2008.

To suggest that a PhD in structural engineering believes that “thermal expansion is a new phenomenon” absolutely demands that one be an utter technological buffoon.

There is NO possible alternative.

Allow me to suggest an alternative interpretation that does NOT require one to be an utter technological buffoon.

"Our study has identified thermal expansion as a new phenomenon that can cause the collapse of a structure."

In other words, what is “new” is the recognition that thermal expansion alone can act as a trigger for progressive collapse.

Which one are you going to choose, gerry?
Buffoon, or buffoon-free?

All you need to do is demonstrate that it is possible for a 53ft beam to expand beyond 5.5" @ 600C. NIST never explained how this was possible, can you?

No, that is not the criteria for the girder to fall off of the seat plate.

Would you like to try again to state the failure condition correctly?
This is NOT just “word games”, but it is one of several crucial errors that you’re making.

BTW, why don’t you use NIST’s value for the thermal expansion coefficient, since they state it exactly. With backup references.

Let’s see if you can get the correct answer for your own question.

Then let’s see if you can figure out how that answer relates to the amount of motion of the girder on the girder seat.

 

[Reactor drone]

I actually think that 5.5" expansion at 600C is a bit on the high side, but that is what the mean CTE of 8.2 gives. The point is that this is still 0.75" less than NISTs explanation requires for WTC7, and way more short that the figure that would be required once the correct elements are considered at the C79 connection.

Fair point, and to be fair, it is a far more complicated thing than I first realised.


Yes, the figure is an average, but 5.5" is still the absolute maximum for this beam, so this means that NIST are 3/4" short of their own revised estimate of 6.25" and way short of what would be required for failure to occur in the manner that they suggested.
It is worth remembering that this assumes that ALL of the expansion occurs in the direction that favours NISTs assertions and at any temp above 600C the beam will begin to sag.
Bottom line - the beam can expand 5.5" at the absolute maximum. In reality, I would say a bit less, but 5.5 is nowhere near what NISTs fantasy explanation would require.

Of course the fire simulation showed temperatures far in excess of 600°C so expansion will be higher and buckling and beam sagging will give a high probability of axial walk off of the girder which will be unaffected by the presence or absence of web stiffeners.

 

[gerrycan]

Of course the fire simulation showed temperatures far in excess of 600°C so expansion will be higher and buckling and beam sagging will give a high probability of axial walk off of the girder which will be unaffected by the presence or absence of web stiffeners.

No, in NISTs simulation the beams were heated to 600. I know it is a pain to do it, but I think it is important to differentiate between the analysis and reality. If NIST say the beam was 600 in their analysis, then that's what it was. Whether it was that temp in reality is more difficult to state with as high degree of accuracy.
Sorry if that sounds like I am nit picking, I don't mean to, but it is crucial to understand that if NIST modeled the seat as 12" and not 11, then the figure of 600c in the beams is not enough to get the push required for the web to move beyond the edge of the seat plate pg in their analysis.

 

[Gamolon]

8.2 in/in-deg F seems to be the mean figure to use for CTE in steel. For steel, your link actually says it is lower (7.3), but stainless would not be the correct figure to use, which would give 9.6 according to that link. I actually think that 5.5" expansion at 600C is a bit on the high side, but that is what the mean CTE of 8.2 gives. The point is that this is still 0.75" less than NISTs explanation requires for WTC7, and way more short that the figure that would be required once the correct elements are considered at the C79 connection.

Fair point, and to be fair, it is a far more complicated thing than I first realised.


Yes, the figure is an average, but 5.5" is still the absolute maximum for this beam, so this means that NIST are 3/4" short of their own revised estimate of 6.25" and way short of what would be required for failure to occur in the manner that they suggested.
It is worth remembering that this assumes that ALL of the expansion occurs in the direction that favours NISTs assertions and at any temp above 600C the beam will begin to sag.
Bottom line - the beam can expand 5.5" at the absolute maximum. In reality, I would say a bit less, but 5.5 is nowhere near what NISTs fantasy explanation would require.

Let me see if I am understanding what your interpretation is regarding all the data NIST has put into their reports...

1. You think the beam needed to be pushed free and clear of the seat in order to fall downward.

2. The distance needed above is greater than the maximum distance thermal expansion could have pushed the beam, therefore the beam flange was still resting on the seat plate in some capacity, trying to resist the load.

3. Based on the the above information, the ONLY conclusion one may draw regarding how the beam failed and fell, is that the flange would have to have failed.

4. Since number 3 above is the only conclusion, the web stiffeners would have prevented this, thus making number 3 impossible.

5. Number 4 thus nullifies NIST's conclusion, which now begs a new study/investigation.

Do I have this right gerrycan?

 

[gerrycan]

To suggest that a PhD in structural engineering believes that “thermal expansion is a new phenomenon” absolutely demands that one be an utter technological buffoon.

Thermal expansion is indeed a phenomenon that is well established and understood by those educated to that level in structural engineering. It is both predictable and quantitative. To think that it would not be accounted for in the structural design of a modern steel highrise such as WTC7 would be a mistake. When NIST released their WTC7 report for public comment the absence of "end plates" on this girder was immediately noted and the question was asked publicly if the presence of these elements might have perhaps prevented such a failure. This question was asked by those within the CTBUH, some of the best PhDs in the business. They asked the question without even having access to the drawings. The building was represented structurally by NIST in such a way to infer that the Phds who designed it did not fully understand the catastrophic implications that thermal expansion could have on the structure. So, yes. The implication that a PhD in structural engineering would not have a full understanding of what thermal expansion is and its potential to compromise a structure would indeed be that of a technological buffoon.

Allow me to suggest an alternative interpretation that does NOT require one to be an utter technological buffoon.
Originally Posted by Shyam Sunder
"Our study has identified thermal expansion as a new phenomenon that can cause the collapse of a structure."

Firstly the collapse would be the new phenomenon referred to in the above quote, not thermal expansion. Maybe Sunder just made a mistake. Allow me to suggest a realistic statement of what NIST actually are saying in the above.
"The potential for thermal expansion to cause the catastrophic failure of WTC7 was not adequately considered by the people responsible for the design."
This would be a far more accurate statement of NISTs contention, however, as the release of the drawings has revealed, the consideration of thermal expansion was adequate in the design of the building, but was misrepresented by NIST, even after their inadequate representation of the critical connection was highlighted to them publicly. They chose not to correct that error.

In other words, what is “new” is the recognition that thermal expansion alone can act as a trigger for progressive collapse.

I would say it was an assertion, not a recognition. As stated above, thermal expansion is well understood. If NIST both released their analysis inputs and accounted for the elements that were present in the drawings that they omitted from their model, the girder spanning columns 79 and 44 would not lose contact with the seatplate when subjected to the temperatures that NIST used.

Which one are you going to choose, gerry?
Buffoon, or buffoon-free?

I will choose that which can be tried tested and proven. NISTs assertions satisfy none of these criteria. That you would defend an agency who at one point claim that the shear studs in these beams failed at around 100C is something that is as indicative of their buffoonery as yours, so stop the name calling and get down to the business of defending that which you intend to, without the childish jibes, if you wish to be taken seriously.

No, that is not the criteria for the girder to fall off of the seat plate.

So just what is the maximum expansion that the longest of the beams to the NE of the girder can experience at the given temperature by your reckoning?

Would you like to try again to state the failure condition correctly?
This is NOT just “word games”, but it is one of several crucial errors that you’re making..

There is no failure condition at the temperatures stated by NIST when the omitted elements are included in the analysis.

BTW, why don’t you use NIST’s value for the thermal expansion coefficient, since they state it exactly. With backup references.

BTW, why do you not use it yourself and them come back and tell us all what the maximum expansion is, that the longest of the beams to the NE of the girder can experience at the given temperature

Let’s see if you can get the correct answer for your own question.

I have stated quite clearly on this thread how far the longest beam can expand. You should try doing the same.

Then let’s see if you can figure out how that answer relates to the amount of motion of the girder on the girder seat.

Yes, let's do that. I welcome that debate. I remain open minded enough to listen to what is said and take it on board. The case made against NISTs explanation is clear enough, your objections to it should be put with similar clarity. Attempts to appear aloof by such foolhardy condescending remarks such as "let’s see if you can figure out....." make it look like you are playing this one by ear, and serve to highlight a dissonant undertone.
Perhaps it would play better to either side of this debate for you to state what interval was required between the girder and the middle of C79, and whether the pitch was East or West. That will perhaps lead to a well tempered discussion.

 

[beachnut]

This question was asked by those within the CTBUH, some of the best PhDs in the business. .

Why does CTBUH not support 911 truth claims of CD, or the insanity of thermite? Is CTBUH rational, or did they make a mistake?

The Council does not agree with the NIST statement that the failure was a result of the buckling of Column 79. We believe that the failure was a result of the collapse of the floor structure that led to loss of lateral restraint and then buckling of internal columns. This is an important distinction, as NIST appears to be seeking improved performance from floors rather than columns.

Wow, you dropped the 911 truth failed CD claims and now support CTBUH, who say their probable cause is collapse of the floor structure, and then the columns failed. And they do agree it was fire.

You are now supporting a probable cause, with the big global cause, fire. Case closed, you are cured.

Wow, wait, you still have the CD claim, one you can't defend, and are cherry picking CTBUH to bash NIST; yet both have probable causes, and you are stuck with the fantasy of silent no blast effects explosives and thermite.

Using CTBUH to bash NIST, and you still can't show your work. Cool

CTBUH does not support your CD claims - fire did it.

 

[jaydeehess]

They asked the question without even having access to the drawings. The building was represented structurally by NIST in such a way to infer that the Phds who designed it did not fully understand the catastrophic implications that thermal expansion could have on the structure.

The designers were PH.D. engineers?

I thought that most practicing engineers were Masters and Bachelor graduates, that PH.D. level is rare for practicing professional engineering.

However, do tell, do the engineers who designed WTC7 take umbrage at being thusly maligned by NIST?

 

[DGM]

So, yes. The implication that a PhD in structural engineering would not have a full understanding of what thermal expansion is and its potential to compromise a structure would indeed be that of a technological buffoon.

The engineers that designed the building also designed in the fire protection to stop this problem.

The buffoon is the one that ignores that fact.

What was the state of the fire protection all day for building 7?

 

[jaydeehess]

When NIST released their WTC7 report for public comment the absence of "end plates" on this girder was immediately noted and the question was asked publicly if the presence of these elements might have perhaps prevented such a failure. This question was asked by those within the CTBUH

So were there end plates?

Oh and same question regarding PH.D. level engineers, and in addition, does the CTBUH accept the tenets of AE911T, or do they accept that fire damage caused the initiating failure and that this then progressed to global collapse?

 

[jaydeehess]

The engineers that designed the building also designed in the fire protection to stop this problem.

The buffoon is the one that ignores that fact.

What was the state of the fire protection all day for building 7?

Or the level of fire suppression.

 

[Animal]

The engineers that designed the building also designed in the fire protection to stop this problem.

The buffoon is the one that ignores that fact.

What was the state of the fire protection all day for building 7?

The troofer buffoon is the one that tries to cherry pick data to fit his narrative while ignoring the rest.

Yes NIST says "figure 10-19 shows that many of the floor beams in the southeast half of the floor reached temperatures around 600 C and remained hot for over and hour." (Pg 396 NIST NCSTAR 1-9)

However, when you actually look at Figure 10-19 9 (pg 412 NIST NCSTAR 1-9) , it clearly shows the beams nearest Col. 79 to be at the extreme end of the color scale (675 C) This has been brought up in the past, and sent carpenter boy scurrying for cover.

Now is another tidbit of information contained in the report that many posters here will understand how it would affect the what really happened and how it would negates other claims made by the troofers buffoons

"Temperature gradients through the depth of the steel beams and girders were affected by the presence of the floor slab. Temperatures were uniform (within 1C) across the bottom flange and web, but the top flange temperature was less by up to several hundred degrees, because the slab acted as a heat sink (see Figure 4-6 to Figure 4-8)" (pg 391 NIST NCSTAR 1-9)

Also -NIST did not model it that way....."The beam elements could model a linear temperature gradient across the section, but a uniform temperature was determined to be a reasonable approximation for the temperature profile in the beam and girder sections." (pg 392 NIST NCSTAR 1-9)

 

[LSSBB]

The troofer buffoon is the one that tries to cherry pick data to fit his narrative while ignoring the rest.

Yes NIST says "figure 10-19 shows that many of the floor beams in the southeast half of the floor reached temperatures around 600 C and remained hot for over and hour." (Pg 396 NIST NCSTAR 1-9)

However, when you actually look at Figure 10-19 9 (pg 412 NIST NCSTAR 1-9) , it clearly shows the beams nearest Col. 79 to be at the extreme end of the color scale (675 C) This has been brought up in the past, and sent carpenter boy scurrying for cover.

Now is another tidbit of information contained in the report that many posters here will understand how it would affect the what really happened and how it would negates other claims made by the troofers buffoons

"Temperature gradients through the depth of the steel beams and girders were affected by the presence of the floor slab. Temperatures were uniform (within 1C) across the bottom flange and web, but the top flange temperature was less by up to several hundred degrees, because the slab acted as a heat sink (see Figure 4-6 to Figure 4-8)" (pg 391 NIST NCSTAR 1-9)

Also -NIST did not model it that way....."The beam elements could model a linear temperature gradient across the section, but a uniform termerature was determined to be a reasonable approximation for the temperature profile in the beam and girder sections." (pg 392 NIST NCSTAR 1-9)

Yes, it's not a linear, uniform problem. Maybe if we just break out the ol' MSPaintFire and an Excel spreadsheet, we can nail this one.

 

[DGM]

Yes NIST says "figure 10-19 shows that many of the floor beams in the southeast half of the floor reached temperatures around 600 C and remained hot for over and hour." (Pg 396 NIST NCSTAR 1-9)

However, when you actually look at Figure 10-19 9 (pg 412 NIST NCSTAR 1-9) , it clearly shows the beams nearest Col. 79 to be at the extreme end of the color scale (675 C) This has been brought up in the past, and sent carpenter boy scurrying for cover.

As everyone remembers, "Truthers" drag out Dr.James Quinterre, as being critical of NIST with their report.

The part they fail to tell is he thinks they were far too conservative.

I went to one of his lectures. He believes they underestimate temps by large margins. He also thinks fire protection standards are still too lax. Odd for someone "truthers" think to be on their side.

 

[jaydeehess]

As everyone remembers, "Truthers" drag out Dr.James Quinterre, as being critical of NIST with their report.

The part they fail to tell is he thinks they were far too conservative.

I went to one of his lectures. He believes they underestimate temps by large margins. He also thinks fire protection standards are still too lax. Odd for someone "truthers" think to be on their side.

Well, the most basic problem for truthers, when they call upon Quinterre, is that he puts no stock at all in the tenets of AE911T.

 

[JayUtah]

Also -NIST did not model it that way....."The beam elements could model a linear temperature gradient across the section, but a uniform temperature was determined to be a reasonable approximation for the temperature profile in the beam and girder sections." (pg 392 NIST NCSTAR 1-9)

In other words, they did it the way I described several pages back. I described the limitations and role of computer simulation and/or simplified mathematics in this exercise, and how it still takes trained experts to interpret the results and reason from them to a plausible conclusion.

Imagining that high-school physics is all you need to solve these problems is enormously naive. Even more naive to suppose that thumping one's fist on a high-school text is sufficient to undermine someone else's much more complex and considered analysis.

There's the old bumblebee analogy. It's a common urban legend to say that according to science, a bumblebee can't fly. But the bumblebee doesn't know that and flies anyway. Digging deeper, the legend is based on applying the wrong (i.e., too simplistic) aerodynamic model to the bumblebee. More accurate and sophisticated models indeed confirm the theoretical ability of a bee to fly.

Charlatans fervently wish their "simple" refutations held up. But the only redeeming quality of these first- (or zeroth-) order models is their simplicity. And that makes them attractive to people who really don't do engineering.

 

[DGM]

And that makes them attractive to people who really don't do engineering.

I'm not sure I'd even go that far. For the "truthers" arguments, you need a generous supply of distrust in authority and a willingness to accept "evidence" that has no basis outside of speculation and fantasy.

Their "smoking gun" is a building the owner did not profit from and had no reason to be a target in the first place.

Is it any wonder their argument is confined to internet forums?