NIST Analysis of Structural Steel

Peephole

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Peephole
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Someone cited this NIST report:

http://wtc.nist.gov/media/P3MechanicalandMetAnalysisofSteel.pdf

Which is supposed to prove that:

-analysis of the paint on thirteen panels shows that these panels never had to endure fires higher than 250°C
-metallurgic analysis of 136 pieces of steel didn't leave any trace of [SIZE=-1]speroidization or something, a crystallographic process that should occurr above [/SIZE]625°C.
-a model of the fire predicts that the developed temperatures never rised above 200-350°C (maximum 450°C)[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular][FONT=Verdana,Arial,Helvetica,sans-serif]

Can someone explain/debunk this?
[/FONT][/FONT]
 
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A couple key points.

Summary of metallographic analysis – Core Columns
• Two core columns in impact area with sufficient paint
• Columns 603 (floors 92-93) and 605 (floors 98-99)
• Paint analyses indicate both columns < 250 °C
Click to expand...
Of the more than 170 areas examined on the exterior panels, only
three locations had a positive result indicating that the steel may
have reached temperatures in excess of 250 ºC.
Click to expand...
Photographic
• Recovered panels mapped for pre-collapse exposure to fire
Paint study
• Paint condition used to map upper limits to
temperature exposure on 21 perimeter panels
Most perimeter panels (157 of 160 locations mapped)
saw no temperature T > 250 °C,
despite pre-collapse exposure to fire on 13 panels
Click to expand...

I bolded the key phrases. The primary support was not exterior or perimeter panels.
 
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DavidJames said:
I bolded the key phrases. The primary support was not exterior or perimeter panels.
Click to expand...


This is not true. The exterior columns were a primary support. What is true is that no one claims the exterior columns were damaged by fire. The interior columns and floor joists were damaged by fire, causing sagging, causing a bowing in the exterior columns (reducing the load they could carry) and then collapse.
 
kevin said:
This is not true. The exterior columns were a primary support. What is true is that no one claims the exterior columns were damaged by fire. The interior columns and floor joists were damaged by fire, causing sagging, causing a bowing in the exterior columns (reducing the load they could carry) and then collapse.
Click to expand...
Ok, my understanding was the exterior columns were mainly to support sway, horizonal support and not primary for vertical support.
 
kevin said:
This is not true. The exterior columns were a primary support. What is true is that no one claims the exterior columns were damaged by fire. The interior columns and floor joists were damaged by fire, causing sagging, causing a bowing in the exterior columns (reducing the load they could carry) and then collapse.
Click to expand...
Okay, thanks!
 
I believe some of the weight support was transferred to the exterior collumns, as Kevin said, but still, by far, the core columns provided support in this area.

I believe very recently the results of a study of the exterior columns by the chief investigation engineer came out, indicating that alot of the exterior columns on the impact floors were severed by the plane as it entered the building. This is attributed to the type of steel used in the exterior columns, which I believe they said was less maleable, and more rigid.

Someone please correct me if I am wrong, as I am recalling from memory only here.

TAM
 
DavidJames said:
Ok, my understanding was the exterior columns were mainly to support sway, horizonal support and not primary for vertical support.
Click to expand...

The exterior columns took almost 100% of the wind load, but it still took quite a bit of the gravity load (I'm trying to find a good estimate as to how much.) Also when many of the interior columns were severed a lot of their load transfered to the exterior columns by way of the hat truss at the top of the buildings, making them more primary then they had been.
 
T.A.M. said:
I believe very recently the results of a study of the exterior columns by the chief investigation engineer came out, indicating that alot of the exterior columns on the impact floors were severed by the plane as it entered the building.
Click to expand...

uh, this was never really in question. There are lots of pictures show a humoungous hole in the side of the building. That would be a severing of exterior columns.

This is attributed to the type of steel used in the exterior columns, which I believe they said was less maleable, and more rigid.
Click to expand...

They may be saying the type of steel used allowed easier penetration of the airplanes and allowed more fuel to distribute inside (i've seen this claim attributed to the lack of masonry on the exterior walls) a stiffer steel might have kept more of the plane outside. I've not seen the report so I'm not for sure.
 
Here it is. NIST report 1-6 pdf page 49.

The primary function of the core columns was to carry the building gravity loads. The exterior columns resisted wind loads and, in addition, carried approximately half of the gravity loads.
Click to expand...
 
Peephole said:
Something else; what about the claims that the columns were able to support five times their gravity loads?

Hoffman claims this:
http://911research.wtc7.net/disinfo/experts/comments/bazantzhou.html

BS?
Click to expand...
It appears Hoffman is debunking an article completed the prior to the end of September 2001, less then 3 weeks after the towers collapsed. I could be wrong, but it wouldn't surprise me if much more was learned in the ensuing years and some of what Bazant and Zhou report may need correction. The Hoffman page you link was last updated 4 years later.

I would be more interested in his comments on the most recent NIST and FEMA reports, the official reports, not something written with days of the collapse.
 
DavidJames said:
It appears Hoffman is debunking an article completed the prior to the end of September 2001, less then 3 weeks after the towers collapsed. I could be wrong, but it wouldn't surprise me if much more was learned in the ensuing years and some of what Bazant and Zhou report may need correction. The Hoffman page you link was last updated 4 years later.
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Yeah, I know but I was just interested in his claim about the gravity loads.
I've seen that pop up a few times.
 
The exterior of the building was build of panels consisting of 3 vertical columns factory welded to 3 horizontal spandrel plates. Each panel was 2 and half stories tall. I believe the width was approx. the same.

They were assembled by bolting the panels together. There was a staggered arrangement so that joints wouldn't line up to create structural weaknessess.

I'm assuming the test was of an entire panel assembly.
 
Can't remember where I saw but I believe the safety factor on the WTC was 2 (which is pretty typical for buildings) not 5. It's probably either in the debunk paper from NIST or an actual report.
 
My understanding is the entire structure was dependent upon 4 things.

- Interior core columns
- Exterior columns
- Floor trusses (to connect and stabalize the above two)
- Hat-truss (to further stabalize and connect the interior/exterior columns)

This is a point that is grossly overlooked by the conspiracy crowd. They will focus on the core columns or the exterior columns saying that they never got hot enough to weaken. Or they will focus on the floors and say that they provided no structural support whatsoever.

The fact is, the towers were constructed with rentable space in mind. The only way to maximize this space was to come up with a way to minimize the support structure. The tube-within-a-tube idea was the answer. These buildings were not over-engineered as many CT claim. They were not "unsinkable".

Each and every part was dependent upon the other. If the core failed, the building would fall. If the exterior columns failed, the building would be knocked over by wind. If the floors failed, the exterior columns would buckle under the weight. If the hat-truss failed, the inner and outer systems would be left alone to support a load they were not designed to support.

As it happened that day, 3 of the 4 structural systems that were in place to keep each tower standing were compromised by the plane impact alone. And that's not even taking into account the fires.

It's amazing they stood as long as they did.
 
The purpose of analyzing samples of steel whose as-built locations could be reliably determined to determine what temperatures they had reached was the same as the purpose of comparing the CFD fire dynamics model's predictions of the spread and extent of the fires with what could be determined from the photographic record, or the predictions of the FEA aircraft impact simulations with the exterior column damage observable in photographs- to test and validate the models' performance.

The steel samples served as test points. If the maximum temperatures determined by analyzing them jibed with the maximum temperatures predicted by the fire dynamics and fire-structure interface models, it indicated that the models were working. They built cube farms, furnished them, instrumented them and lit them on fire to compare the upper layer temperatures predicted by modeling with those measured in actual controlled fires for the same reason- to test the performance of the modeling. In fact, they did this repeatedly under different conditions to study the effects of the aircraft impacts' trashing of offices and how this should affect the inputs to their fire models.

Testing them for such parameters as composition, strength and elasticity served to provide data for modeling the behavior of structural elements made of those materials.

If I run a simulation of a circuit I'm designing and then build the circuit and take measurements, I only need a set of selected test points to determine whether or not the sim is predicting the circuit's behavior with reasonable accuracy, not measurements of every node voltage and branch current in the whole megillah, because all of those parameters are coupled- if the sim is significantly wrong at one point it will probably be wrong at others, while if it's right at several important points it will probably be right all over.

Similarly, the comparison of empirical data to the predictions made by modeling increased NIST's confidence that the much higher temperatures predicted for some core columns and floor trusses were likely to be correct within an acceptable error.

Some CTists will claim that NIST's findings can't be validated without empirical data from every column and truss in the towers.

They are wrong.

Some will claim that the temperatures found for the tested steel mean that none of the steel could have gotten hot enough to seriously affect the structure.

They are also wrong.
 
minor technical corrections
realitybites said:
- Floor trusses (to connect and stabalize the above two)
Click to expand...

the floor trusses were mainly to support the floors, but they did do some load transfer from the exterior to the interior of the building. A damper was installed on the floor joists at the exterior columns to reduce the amount of load transfer from exterior to the core.

- Hat-truss (to further stabalize and connect the interior/exterior columns)
Click to expand...

The hat truss was originally designed to support the roof top antennas (both had the trusses, although only one had an antenna). They weren't actually needed to stabilize and connect the columns, but when the core columns were severed it did do this as well.
 
kevin said:
This is not true. The exterior columns were a primary support. What is true is that no one claims the exterior columns were damaged by fire. The interior columns and floor joists were damaged by fire, causing sagging, causing a bowing in the exterior columns (reducing the load they could carry) and then collapse.
Click to expand...
So what were the temperatures reached by the interior columns?

And what were the main differences between the 9/11 attacks and the 1975 fire?
 
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