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Banned
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I guess no one here read my post on the "Rice....Memo"
thread. NIST is still conducting the most comprehensive
forensic investigation of the WTC towers. At their meeting in
Oct. 2004, the NIST investigators results so far do not support the jet fuel fire or heat from it, being the cause of the
collapse of either tower.
Quote:
<a href="http://fe.pennnet.com/Articles/Article_Display.cfm?Section=ARCHI&ARTICLE_ID=133237&VERSION_NUM=1">http://fe.pennnet.com/Articles/Article_Display.cfm?Section=ARCHI&ARTICLE_ID=133237&VERSION_NUM=1</a>
( Bill Manning Fire Engineering January, 2002)
Fire Engineering magazine, the 125-year old journal of record among America’s fire engineers and firefighters, recently blasted the investigation being conducted by the Federal Emergency Management Agency (FEMA) of the collapsed World Trade Center as a “a half-baked farce.”
Fire Engineering’s editor, William Manning, issued a “call to action” to America’s firefighters and fire engineers in the January issue asking them to contact their representatives in Congress and officials in Washington to demand a blue ribbon panel to thoroughly investigate the collapse of the World Trade Center structures.
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<h2>The NIST Investigators so far, cannot find the reason why either WTC Tower collapsed !</h2>
Quote:
<a href="http://wtc.nist.gov/media/gallery.htm#recover">http://wtc.nist.gov/media/gallery.htm#recover Gallery of Recovered World Trade Center Steel at NIST</a>
<a href="http://www.nist.gov/public_affairs/ncstmin_oct19-20.htm">The National Construction Safety Team Advisory Committee
National Institute of Standards and Technology (WTC INVESTIGATION)
Minutes of October 19 - 20, 2004, Meeting - Gaithersburg, Maryland</a>
(Following is from the first Q&A...near the top of the web page)
Q: Referring to the column shortening in WTC 1, is the elastic strain reported at room temperature?
A: No. The values reported are for elevated temperature. The history is traced, including degradation of properties.
Q: For test 1 of the fire resistance tests of the floor systems at Underwriters Laboratories, you show unrestrained rating of one hour. Was that an analytical conclusion or a tested result?
A: We show in each case an unrestrained rating when we actually did a restrained test. What we are showing there is not the result of an actual unrestrained test, but the temperature criteria in the standard for a restrained test.
C: Right, one of the major significances of the series of these tests is that test 2 was an unrestrained test and showed superior performance.
<b>
Q: I want to ask about the floor performance. The way I understood your description of the collapse scenario, the behavior of the floor systems was not a central issue. Can you connect the floor results with that?
A: The results reinforce each other. The results of the fire test versus the load test support the finding that the floors were not a driving force in the collapse.</b>
(Following Q&A is from the middle of the web page.....)
Q: In the absence of impact, fire only, burnout would have been achieved and the building would not have collapsed? Am I interpreting that correctly?
A: Yes. For the fires we have analyzed to date for floor systems with ¾ inch fireproofing in place, even with gaps observed in photographs, the floors would have deformed, but would not have initiated collapse.
A: We have looked at credible fires in an undamaged tower. Remember, for this scenario, there would not be broken windows to supply oxygen to fuel the fire. This is a working hypothesis and analyses remain to be completed.
Q: Regarding the findings for global analysis with impact damage, I want to make sure I’m interpreting the information correctly for floor 96 in WTC 1. At 600 seconds, there’s 23 inches of deflection on the trusses. When the fires move away, the trusses restore to 6 inches of deflection?
A: Yes. The 23 inches is next to the impact area.
C (NIST): Referring to the slide on global analysis without impact damage. You have a statement that burnout was likely prior to collapse. This infers that collapse would occur. You may want to change your wording to say burnout without collapse.
A: Agree.
Q: Do you have a complete run for the entire buildup of the tower?
A: We have completed the realistic case for WTC 1. The realistic case for WTC 2 is running and may be completed later today. We’ve also done the component analyses.
Q: Can you envision another set of conditions that gives the same observed failure mechanism?<b>
A: We had to remove four to five floors to get global instability.
A: We looked at this very carefully. We could not find a way to make the building come down.</b>
(The following Q&A is located near the bottom of the web page
<b>Read the bold print paragraph. Recycling the steel was premature</b>)
The last areas covered were a review of the findings from Project 3 and a description of the Investigation issue associated with Project 3. The issue deals with the use of "fire-resistant" steel in the United States, especially the appropriate measurement methods to characterize properties, and the codes in the United States, Japan, and Europe, which tend to encourage or discourage the use of such steels.
Q: I have a problem with the statement that the steel collected for the investigation is adequate. If I were doing an accident reconstruction, I would’ve been looking for core columns that were hit by the aircraft. It may be okay from a research perspective. It should not be stated that it is adequate from an investigation point of view.
A: It would have been nice to have, but may have been very hard to find. There is an issue of how the pieces hit would have survived and how they could be identified.
Q: If you go to the site, you look for pieces of the right size, etc. NIST never had the opportunity to do this type of search.<b>
A: The Structural Engineers Association of New York (SEAoNY) started collecting steel in October of 2001. NIST was a member of that team. That team had a list of steel to look for. Some steel had disappeared and was recycled. NIST took over 8 months before the investigation began. We did not have reconstruction in mind. That would have been extremely expensive for us to do. We tried to get all grades of steel. We tried to get pieces from the impact zone, fire affected pieces, etc. If we had the authority, we would have been more aggressive.</b>
Q: That’s what I’m saying. Looking down the road to future incidents, NIST should have the authority to preserve evidence useful for an investigation.
A: We’ll qualify that statement.
Q: The hypothesis is that core columns got above 600 ºC. It would be nice to have pieces of steel to support that hypothesis. You do have trusses from above the floors of impact?
A: None of the trusses could be identified as to location, only the truss seats that were considered part of the panels.
Q: Have you analyzed the truss seats?
A: Yes, but the steel for the truss seats was from various sources, so there was no baseline material for comparison purposes for metallography.
C: As John Barsom said, the statement is not accurate. The validity of the model question from yesterday speaks to this issue. I do not believe that we have enough forensic evidence. It may be okay to establish steel quality. There was no effort by the Building Performance Study team to systematically look at the steel.
C: The use of the term “adequate” needs to be revisited. There is no core column test to support the hypothesis. The floors came down, the slabs were pulverized. This was unprecedented. Exterior columns and core remained. The floors group will attack this finding.
C: With the low data points for the yield strength as shown on the slides, it does not appear to indicate that the steel meets the specifications. You need to flag the reasons for these outliers. Compression is a factor. Properties can change due to compression even if there is no deformation. This needs to be stated. Fire resistant steel claims by Japan are false. There is hardly any difference. The difference is in the modeling done in Japan. These steels would not perform better than U.S. materials. You need to concentrate on the performance of steel as it is tested—look at weldability, high-temperature chrome steels. Also, the cost of such steel may be a factor.
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