Total Building Collapse from a Single Column Failure

[JSanderO]

[qimg]http://conleys.com.au/smilies/thumbup.gif[/qimg] Yes. I'm being somewhat generous to Sander's hypothesis. There is no proof for either of these hypotheses - or any other that may be dreamed up. If we were to compare probabilities there is quite a bit more going for the NIST one. However this thread is Sander's OP. Sander resists even acknowledging that the NIST hypothesis is plausible and my purpose has been to persuade Sander to recognise that the NIST one is plausible and that neither his nor NIST's is ultimately provable - as per the summary in my previous post. (And several previous versions of then same thing. I can be stubborn )

Remember also that, despite all the lengthy but falsely premised arguments form both sides, no one (at least on this forum) has falsified the NIST girder walk-off hypothesis.

Of course neither theory is provable. The issue in my mind is what is a probable or reasonable explanation supported by the evidence. Yes NIST does not report fires etc in the TT region. I say... so what? You can't say something didn't affirmatively because you find no evidence of it. How was that actually determined?.... no fires down there? Who said you need massive fires with lots of smoke? Imagine a broken diesel pipe with a jet of pressurize fuel burning like a gas jet and on a small region like a connection. Possible? Who knows? But a lance is a pretty focused heat heating device and it could cut through the connections.

I still have not read in this thread how girder walk off can fail column 79 and then 79 taking the who building down. I am not saying it's impossible. I am asking for someone to summarize the MECHANISM... the steps.

I have not heard any one explain how the diesel fuel was recovered.... and how much? If a credible account of the diesel recovery which included all the diesel, that would rule out diesel as an accelerant.

I don't resist... I am skeptical... What I DO know of what NIST has proposed is not selling me.

Sell me.

 

[JSanderO]

iirc, there is no evidence of a proximate cause of a TT1 failure. JSO postulates diesel fuel fires but both FEMA and NIST could not support such a scenario given no evidence that such fires were ever underway.
OTOH fires on the 12th floor are known to have been in play.

Says who? NIST will make such a claim because it SUPPORTS their theory...well DUH

I don't deny their were lots of fires in the building. I'd just like to know how they figured the hot spot was the girder framed into column 79 on floor 13?

You tell me.

 

[Robrob]

Says who? NIST will make such a claim because it SUPPORTS their theory...well DUH

I don't deny their were lots of fires in the building. I'd just like to know how they figured the hot spot was the girder framed into column 79 on floor 13?

You tell me.

What I want to know is why Truthers seem to have a laser like focus on minutia while ignoring the overall events of the day? It's like Xeno's Paradox. You try to explain things to them and they just move a fraction ahead to another, more minute point.

 

[JSanderO]

What I want to know is why Truthers seem to have a laser like focus on minutia while ignoring the overall events of the day? It's like Xeno's Paradox. You try to explain things to them and they just move a fraction ahead to another, more minute point.

Robrob,
I have no idea. I don't consider myself a debunker nor a truther. I do think there is some wisdom in the Miesian notion that "god is in the details*. That is, if you want to truly understand something you need to drill down to the detail level... and depart the crib sheet version.

It's sort of like explaining to someone how a sailboat works...

crib sheet version: wind makes sailboats move.
detail version: Sailing-Theory-Practice by C-Marchaj (http://www.amazon.com/Sailing-Theory-Practice-C-Marchaj/dp/0396084281)

You wanna understand sailing... you need to tackle Marchaj. It's that simple.

 

[BasqueArch]

Says who? NIST will make such a claim because it SUPPORTS their theory...well DUH

I don't deny their were lots of fires in the building. I'd just like to know how they figured the hot spot was the girder framed into column 79 on floor 13?

You tell me.

Ok. It’s in NCSTAR1A for those who have read it.
They used the Fire Dynamics Simulator:

3.4.3 Fire Dynamics Simulator ( FDS )
The major fires on Floors 7 through 9 and 11 though 13 in WTC 7 were simulated using the Fire Dynamics Simulator (FDS), version 4, in a manner similar to the simulations conducted for WTC 1 and WTC 2 (NIST NCSTAR 1-5F). There were far fewer photographs and videos of WTC 7 than of the towers; and, thus, the details of the WTC 7 fires were not as precise as for the fires in the towers. However, the imagery was sufficient to guide the WTC 7 fire simulations. Unlike the computations for WTC 1 and WTC 2, the fire simulations for WTC 7 were conducted for each floor individually, as there were no obvious pathways for the flames and heat to pass from one floor to another, aside from the debris-damaged area in the southwest corner of the building (NIST NCSTAR 1-9, Chapter 9). The fires on Floors 7, 8, and 12 were simulated using input from the visual imagery and established fire physics. The fire on Floor 9 was similar to that on Floor 8, and the simulation was derived from it. For the same reason, the fires on Floors 11 and 13 were derived from the fire on Floor 12. While use was made of the appearance of flames and window breakage in photographs and videos in formulating the simulations, the Investigation Team realized that the absolute timing of the simulations might not align exactly with the timing of the fires on September 11, 2001. A typical single floor fire simulation took up to two days on a Linux cluster with 8 processors. (NCSTAR1A_p66)

http://911encyclopedia.com/wiki/index.php/World_Trade_Center_7_NIST_Collapse_Simulation

Here’s the Floor 12 fire simulation: http://nate.flach.s3.amazonaws.com/12th-Floor_Fire.wmv

NIST says that given the complexity of the modeled behavior, the global collapse analyses matched the observed behavior reasonably well.

3.5.3 Accuracy Appraisal
Given the complexity of the modeled behavior, the global collapse analyses matched the observed behavior reasonably well. The close similarity of the timing and the nature of the events up to the initiation of global collapse is strong confirmation of the extent and nature of the structural failures in the interior of the building and the accuracy of the four-step simulation process. The overall simulation of the collapsing building with damage better matched the video observations of the global collapse. The global collapse analysis confirmed the leading collapse hypothesis, which was based on the available evidence. (NCSTAR1A_p78)

ibid.
NIST used the Fire Structure Interface (FSI) to impose the gas temperatures from the FDS simulations on the structural components of WTC 7 to predict the evolving thermal state of the building:

3.4.4 Fire Structure Interface (FSI)
The Fire Structure Interface (FSI) was used to impose the gas temperatures from the FDS simulations on the structural components of WTC 7 to predict the evolving thermal state of the building (NIST NCSTAR 1-9, Chapter 10). The thermal analysis approach was similar to that used to simulate the fire induced thermal loads on WTC 1 and WTC 2 described in NCSTAR 1-5G. The FDS temperature data for use in the structural analysis were sampled at 30 min intervals. For each time step, a set of thermal data files was generated that specified the thermal state of the lower 16 stories of the building. Three different thermal response computations were used. Case A used the temperature data as obtained from the FDS simulation. Case B increased the Case A gas temperatures by 10 percent and Case C decreased the Case A gas temperatures by 10 percent. Given the limited visual evidence, the Investigation Team estimated, using engineering judgment, that a 10 percent change in temperatures was within the range of reasonable and realistic values for the fires in WTC 7 on September 11, 2001. The computational time for each Case was approximately one to two days on a single processor desktop computer. (NCSTAR1A_p66)

ibid.
The FDS is free software developed by NIST, so it can be tested by others, such as any of the thousands at AE911T or present company.

Fire Dynamics Simulator (FDS)

is a computational fluid dynamics (CFD) model of fire-driven fluid flow. The software solves numerically a large eddy simulation form of the Navier-Stokes equations appropriate for low-speed, thermally-driven flow, with an emphasis on smoke and heat transport from fires.
FDS is free software developed by the National Institute of Standards and Technology (NIST) of the United States Department of Commerce, in cooperation with VTT Technical Research Centre of Finland. Smokeview is the companion visualization program that can be used to display the output of FDS.

The http://en.wikipedia.org/wiki/Fire_Dynamics_Simulator

 

[Seymour Butz]

I still have not read in this thread how girder walk off can fail column 79 and then 79 taking the who building down. I am not saying it's impossible. I am asking for someone to summarize the MECHANISM... the steps.

.

This is, of course, a lie.

You've been told at east once that what seems to be your understanding of the sequence of events - girder walkoff -> column failure is wrong.

The correct sequence is girder walkoff ( and yet another wrong statement from you is that this was a hotspot) -> floor failure and collapse -> several floors collapsing -> col 79 being unbraced on at least one side (cuz there's no way any sane rational person could envision that the floors/framing on the adjacent sides would be in pristine condition) -> Euler's buckling of 79 (over several stories) -> completion of failure of floors and framing around 79's former position (over several stories) -> cascading collapse.

IIRC, you've confessed to formerly being a truther? With this glaring lie, and the continued misrepresentation of what NIST and other members have said, then I can see how that happened.....

 

[JSanderO]

Ok. It’s in NCSTAR1A for those who have read it.
They used the Fire Dynamics Simulator:
http://911encyclopedia.com/wiki/index.php/World_Trade_Center_7_NIST_Collapse_Simulation

Here’s the Floor 12 fire simulation: http://nate.flach.s3.amazonaws.com/12th-Floor_Fire.wmv

NIST says that given the complexity of the modeled behavior, the global collapse analyses matched the observed behavior reasonably well.
ibid.
NIST used the Fire Structure Interface (FSI) to impose the gas temperatures from the FDS simulations on the structural components of WTC 7 to predict the evolving thermal state of the building:
ibid.
The FDS is free software developed by NIST, so it can be tested by others, such as any of the thousands at AE911T or present company.
The http://en.wikipedia.org/wiki/Fire_Dynamics_Simulator

I'm a bit dense but this seems to be a model simulation not based on real world data input... or am I misunderstanding this?

 

[JSanderO]

This is, of course, a lie.

You've been told at east once that what seems to be your understanding of the sequence of events - girder walkoff -> column failure is wrong.

The correct sequence is girder walkoff ( and yet another wrong statement from you is that this was a hotspot) -> floor failure and collapse -> several floors collapsing -> col 79 being unbraced on at least one side (cuz there's no way any sane rational person could envision that the floors/framing on the adjacent sides would be in pristine condition) -> Euler's buckling of 79 (over several stories) -> completion of failure of floors and framing around 79's former position (over several stories) -> cascading collapse.

IIRC, you've confessed to formerly being a truther? With this glaring lie, and the continued misrepresentation of what NIST and other members have said, then I can see how that happened.....

Stuff the ad homs Butz....

My understanding was that NIST based the theory of collapse on a girder walk off starting it... that was the result of thermal expansion. If the girder walk off was not the last straw then what was?

Be a nice fella and simple list the steps of the sequence from fire to collapse and include in your answer (sequence) girder walk and column 79 failure.

Thanks!

 

[Justin39640]

I'm a bit dense but this seems to be a model simulation not based on real world data input... or am I misunderstanding this?

What real world data? No one had sensors in 7WTC to collect it. They had to simulate conditions in labs (live burns, materials tests, etc) to get that data and build software. Why do you think it took years to finish the reports?

 

[Justin39640]

Stuff the ad homs Butz....

My understanding was that NIST based the theory of collapse on a girder walk off starting it... that was the result of thermal expansion. If the girder walk off was not the last straw then what was?

Be a nice fella and simple list the steps of the sequence from fire to collapse and include in your answer (sequence) girder walk and column 79 failure.

Thanks!

The girder walked off and allowed the flooring to collapse, which collapsed the floor below and so on for a bunch more floors. That left 79 unbraced. It fails taking the EMP down. It also causes more damage that leaves other columns unbraced or at least partially, they fail and the sequence continues form east to west. Then the unbraced facade collapses.

Ta-da!

 

[Animal]

I'm a bit dense but this seems to be a model simulation not based on real world data input... or am I misunderstanding this?

Real world data? You want the torque on every bolt connection? The real world data on every weld? Analysis of every piece of steel for conformance to specifications. Then move on to every location of every shred of flammable material in the building. Also the exact location of every item for live load. How about logs for every concrete pour plus core to verify the thickness down to the mm. The lets move on to wind speed and gusts.....we will need those at every floor height and various locations throughout the structure on all sides to help determine fanning of flames. I could go on, but most people will get the point.

 

[JSanderO]

The girder walked off and allowed the flooring to collapse, which collapsed the floor below and so on for a bunch more floors. That left 79 unbraced. It fails taking the EMP down. It also causes more damage that leaves other columns unbraced or at least partially, they fail and the sequence continues form east to west. Then the unbraced facade collapses.

Ta-da!

thanks!

 

[JSanderO]

Real world data? You want the torque on every bolt connection? The real world data on every weld? Analysis of every piece of steel for conformance to specifications. Then move on to every location of every shred of flammable material in the building. Also the exact location of every item for live load. How about logs for every concrete pour plus core to verify the thickness down to the mm. The lets move on to wind speed and gusts.....we will need those at every floor height and various locations throughout the structure on all sides to help determine fanning of flames. I could go on, but most people will get the point.

So the main inputs to the simulation were assumptions... is that correct?

 

[Seymour Butz]

Stuff the ad homs Butz....

My understanding was that NIST based the theory of collapse on a girder walk off starting it... that was the result of thermal expansion. If the girder walk off was not the last straw then what was?

Be a nice fella and simple list the steps of the sequence from fire to collapse and include in your answer (sequence) girder walk and column 79 failure.

Thanks!

So then you really don't know?

And yet you have the gall to be implying earlier that there should be architects and/or engineers being punished for the building collapsing?

Justin covered it too but:

1- WTC1 falls on 7 and info ifht fires are a result

2- FDS indicates that the girder would have thermally expanded enough, despite intact fireproofing, to walk off its support

3- the part of the 13th floor supported by that girder and its beams, which was larger than in other areas of the building, collapses onto the 12th floor.

4- the 12th floor and its framing was also hot and so it and the 13th floor collapses. And on down until the technical floor on the 7th(?), which had a thicker concrete floor.

5- somewhere during step 3 and 4, or at its completion, col 79, which is unbraced on at least one side now due to collateral damage during the collapse of those several floors, succumbs to Eulers buckling, and the EPH falls into the building, further damaging floors and framing between 79,80, and 81 and the core columns.

6- the collapse proceeds chaotically from east to west inside, with any or all of these events overlapping.

 

[Animal]

So the main inputs to the simulation were assumptions... is that correct?

The main inputs would have been based on the building specifications. Fire spread is based on known room configuration, average fuel load, known broken windows etc. There is no way to account for the thousands upon thousands of variables in a building of that size. Even one or two displace or damaged ceiling tiles could alter the fire progression. Doors open vs closed would could similar differences.

Why such difficulty understanding a simulation is a simulation?

 

[JSanderO]

The main inputs would have been based on the building specifications. Fire spread is based on known room configuration, average fuel load, known broken windows etc. There is no way to account for the thousands upon thousands of variables in a building of that size. Even one or two displace or damaged ceiling tiles could alter the fire progression. Doors open vs closed would could similar differences.

Why such difficulty understanding a simulation is a simulation?[/QUOTE

I completely understand what a simulation. My point was that there was little to no evidence that they used to explain what happened.

They used assumed input aside from the structure and produced their "theory". But change the inputs or the fire spread or the accelerants and things can change.

From what I saw... the GIF which is what the simulation produced did not resemble the real world collapse.

Right?

 

[Animal]

The main inputs would have been based on the building specifications. Fire spread is based on known room configuration, average fuel load, known broken windows etc. There is no way to account for the thousands upon thousands of variables in a building of that size. Even one or two displace or damaged ceiling tiles could alter the fire progression. Doors open vs closed would could similar differences.

Why such difficulty understanding a simulation is a simulation?[/QUOTE

I completely understand what a simulation. My point was that there was little to no evidence that they used to explain what happened.

They used assumed input aside from the structure and produced their "theory". But change the inputs or the fire spread or the accelerants and things can change.

From what I saw... the GIF which is what the simulation produced did not resemble the real world collapse.

Right?

It resembled the collapse initiation. An attempt to model the collapse after that....with the thousands of individual pieces and millions of interdependent variables would be pointless.

 

[jaydeehess]

Says who? NIST will make such a claim because it SUPPORTS their theory...well DUH

I don't deny their were lots of fires in the building. I'd just like to know how they figured the hot spot was the girder framed into column 79 on floor 13?

You tell me.

you'll note that I said that neither NIST, or the earlier FEMA investigations found any support for a diesel fuel fed fire.
NIST in fact ignored the FEMA report before doing their own work on the subject. You can read what they looked for wrt evidence, in the WTC 7 reports.
I have also mentioned before that simple paranoid reasoning (NIST was CYAing so you can't believe them) doesn't do it for me. In this case though you are using the very same reasoning that a truther, Chris Sarns, used when the WTC 7 interim report outlined the reasoning FOR investigating a diesel fuel fed fire. Sarns said that NIST was setting themselves up with a ready excuse for WTC 7 collapse, that they would say that generator fuel fire weakened structure at the 5th floor. He went on and on about NIST 'lies' all based on the idea that this would be the cause of collapse. Now you are saying that NIST concluding no fuel fed fires are 'lies' designed to bolster their final hypothesis.

How odd that NIST is damned both ways.

 

[Newtons Bit]

It resembled the collapse initiation. An attempt to model the collapse after that....with the thousands of individual pieces and millions of interdependent variables would be pointless.

And of course the fact that they omitted the stud walls and sheathing for what should be obvious reasons.

 

[JSanderO]

you'll note that I said that neither NIST, or the earlier FEMA investigations found any support for a diesel fuel fed fire.
NIST in fact ignored the FEMA report before doing their own work on the subject. You can read what they looked for wrt evidence, in the WTC 7 reports.
I have also mentioned before that simple paranoid reasoning (NIST was CYAing so you can't believe them) doesn't do it for me. In this case though you are using the very same reasoning that a truther, Chris Sarns, used when the WTC 7 interim report outlined the reasoning FOR investigating a diesel fuel fed fire. Sarns said that NIST was setting themselves up with a ready excuse for WTC 7 collapse, that they would say that generator fuel fire weakened structure at the 5th floor. He went on and on about NIST 'lies' all based on the idea that this would be the cause of collapse. Now you are saying that NIST concluding no fuel fed fires are 'lies' designed to bolster their final hypothesis.

How odd that NIST is damned both ways.

I am not concluding anyone lied. I want to see the evidence of the fuel recovery and how they excluded diesel fires. My sense is that there was really no data about what was going on inside the sub station and the floors above it. If there are any reports of this I am unaware of them.

So not having reports does not mean there was nothing going on there. This seems to be the logic here... no reports of fire so there was none. But there were no affirmative reports that there WAS no fire in this region. Two very different things.