Sinclair
Moderate Poster
Joined: 10 Aug 2005
Posts: 395
Location: La piscina de vivo
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 Posted: Tue Jan 10, 2006 11:17 pm Post subject: NIST etc. |
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Ian,
Comments submitted during the 'public consultation period' of the NIST WTC1&2 reports are available at [url]
http://wtc.nist.gov/wtc_public_comments.htm[/url].
I thought that Dr Barbara Lane or Arup Fire was leading the (Arup) comment on the inadequacey of the NIST analysis?!
Unfortunately the lonks at that page link to MASSIVE PDF files (i.e. the Barbara Lane PDF is over 30MB in size! This makes the process of studying the public comments VERT laborious & time consuming.
Incidentally, on recently checking the NIST website ( http://wtc.nist.gov/ ) there was a recent post regarding the long awaited WTC7 report.
Here is a copy of a post I made on another board:
| Quote: | From http://wtc.nist.gov/media/WTC7_draftSOW.htm , 'NIST is interested in receiving technical comments about the scope of work and technical approach for The draft statement of work for structural analysis of WTC 7
This is somewhat behind the NIST previously stated timetable for the scheduled FINAL WTC7 report issue date of December 2005........The timetable (from the document) will now be no earlier than November 2006.
The PDF document at http://wtc.nist.gov/media/Draft_SOW_WTC7jan06.pdf provides details of the draft statement of work for the WTC7 analysis required.
This webpage was updated on 4th Jan 2006 & for any contractors to be considered, they must contact NIST on or before January 10, 2006. That does not give any independent companies much time!
It'll be interesting to note to whom the contract goes to, & what their previous association/history is with the NIST/Bushco government.
Some interesting excerpts from the Draft Statement of Work Document:
Quote:
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Previous Analyses
Previous analyses were conducted by NIST as part of the WTC Investigation. [So the best US Goverment Scientists cannot come up with a theory that fits!!] The work will be made available to the Contractor as background information. The work of the Contractor shall not be limited by these models, hypothesis, or analysis results. A working collapse hypothesis is described in the June 2004 Progress Report on the Federal Building and Fire Safety Investigation of the World Trade Center Disaster (Volume 1, pg 17), as follows:
• An initial local failure at the lower floors (below floor 13) of the building due to fire and/or debris induced structural damage of a critical column (the initiating event), which supported a large span floor bay with an area of about 2,000 ft2,
• Vertical progression of the initial local failure up to the east penthouse, as large floor bays were unable to redistribute the loads, bringing down the interior structure below the east penthouse; and
• Horizontal progression of the failure across the lower floors (in the region of floors 5 and 7 that were much thicker and more heavily reinforced than the rest of the floors), triggered by damage due to the vertical failure, resulting in disproportionate collapse of the entire structure.
This hypothesis may be supported or modified, or new hypotheses may be developed through the course of this study. [i.e. anything that fits, please!!!]
Previous models and analyses included:
• Identification of events and data from photographs, videos, and witness accounts.
• Studies of fire spread and growth on Floors 5, 7, and 8.
• Studies of heat transfer to Core Columns 79, 80, and 81 on Floors 5, 7, and 8.
• SAP2000 linear global model of WTC 7, which was based on structural drawings, that included beam elements for columns and floor beams, and representative shell elements for reinforced concrete floor slabs. The model was evaluated for design gravity and wind loads, service gravity loads, and stability for damage conditions caused by debris impact.
• Studies of Core Column 79 (see Appendix A) response to elevated temperature profiles for collapse initiation, using Mathcad calculations and an ANSYS shell element model.
• SAP2000 model of a single floor model representative of Floors 8 to 46. The floor model was more detailed than the floors in the global model; plastic hinges were added at specific locations to beams and columns. Core columns support was removed (i.e. Columns 76 to 81 were removed individually in separate analyses) to determine the mode of floor failure as part of the analysis of the vertical progression of failure.
• SAP2000 model for the horizontal progression analyses of failure across the lower core columns. The model was extracted from the global model and plastic hinges were added at specific locations to beams and columns. The horizontal progression was analyzed by removal of components or application of an action resulting from a failure of Floor 5 or Floor 7.
• SAP2000 kinematic model (frame elements with all beam-columns connections assumed to be pinned) was used to evaluate the effect of assumed column failures and determine the resulting deformed shape of the structure.
The models will be made available to the Contractor for use as appropriate. The input files have been updated to SAP2000 version 10.
Objective
The objective of this solicitation is (1) to conduct analyses that support the determination of the location and cause of the initiating event and the probable collapse sequence, in conjunction with parallel NIST analyses, and (2) to validate the results with observations from video and photographic records and other evidence.
Scope of Work
In this scope of work, the determination of the location and cause of the initiating event is given primary importance. The sequence of failures following the initiating event that led to global collapse, while also important, is dependent upon the proper identification of the initiating event.
While the sequence of failures following the initiating event may be adequately addressed with less detailed analyses, the analyses must be of sufficient rigor to support the identification of the probable sequence of failures.
For all tasks included in this solicitation, the models, assumptions, and analyses will be subject to review and approval by NIST. NIST will arrange for third parties to conduct independent reviews before final approval. NIST plans to retain a third party expert in structural system behavior, structural stability, and failure criteria for members and system failure. The third party expert will provide expert technical assistance to guide and assist the Contractor’s work, but it is the Contractor’s responsibility to conduct the work described in this SOW. Third party experts will also review Contractor reports for: (1) appropriateness of the models for their intended uses, including modeling assumptions, level of detail, model geometry and material properties, and
verification and validation procedures; and (2) appropriateness of the analyses and accuracy of results.
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So it seems that NIST have had difficulty in undertaking the analysis themselves & now wish to sub-contract out the difficult 'donkey work' to a contractor who will play along. Advance notice of this iminent Work Package MUST have been given to the likely winning contractor as it would be impossible for any contractor to prepare the price for & submit such a bid within the 5 day 'notice of Interest' period given.
The use of a sub-contarctor (who will dance to the NIST Paymaster) will allow the excuse to be used when the analysis is criticised (as was used before in relation to criticisms of the NIST's reluctance to fully model the collapse visualisation & initiating events [NCE article of 6th October 2005]) along the lines of "Well, it was a sub-contractor & we have now terminated his contract.
The WTC7 report sure is proving difficult to produce..............
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Sinclair
Moderate Poster
Joined: 10 Aug 2005
Posts: 395
Location: La piscina de vivo
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| Posted: Tue Jul 04, 2006 8:50 am Post subject: |
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GeorgeW,
I have PM'd you.
Thanks for bringing this thread up again. I did a bit of searching on the latest for any news on the NIST (long-awaited) report into the collapse of WTC7, & found these articles from the 'NEW CIVIL ENGINEER' site http://www.nceplus.co.uk (which WAS a members only site, but is now free for anyone to use/browse/search):
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From http://www.nceplus.co.uk/fastsearch/ArchiveArticleAssetPT/?AID=24208
Final probe into WTC7 tower collapse set to start
New Civil Engineer 30 March 2006
FINAL STRUCTURAL analysis of the unexplained collapse of the "third tower" at the World Trade Center will begin in April, the US team investigating 9/11 confirmed this week.
WTC7 was a 47 storey building that was damaged and set on " by debris from the collapsing twin towers. Experts were initially baffled by its sudden collapse after seven hours of multifloor fires.
The investigation of WTC7's demise was added to the brief of the National Institute for Science & Technology (NIST) in August 2002. NIST has now said it hopes to award the contract for "development of WTC7 structural models and collapse hypotheses" in the near future.
"We hope to publish a draft report for comment by the fall (autumn)", a spokesman added.
As on the investigation into the Twin Towers, the analyses will be carried out by independent specialist consultants.
NIST said it had taken so long to get to this stage of the WTC7 investigation because the Twin Towers were a priority.
"We did have staff allocated to WTC7 at the beginning, but when we realised how complex the Twin Towers project would be we switched all resources over there."
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From http://www.nceplus.co.uk/fastsearch/ArchiveArticleAssetPT/?AID=21981
Row erupts over why twin towers collapsed
New Civil Engineer 22 September 2005
A ROW over the causes of the World Trade Center twin tower collapses on 11 September 2001 broke out between British and American fire engineers last week.
British engineers strongly disputed official American claims that the towers became more vulnerable to collapse after the hijacked aircraft scraped vital fire protection from their steel frames.
The twin towers collapsed when each caught fire after terrorists flew hijacked Boeing passenger jets into them.
The disagreement provoked a strong exchange of views at a major conference held at Gaithersburg near Washington DC to discuss the official findings of America's National Institute for Standards & Technology (NIST) investigation into the 9/11 collapses.
"We don't believe that NIST has satisfactorily demonstrated that the loss of fire proofing was the deciding factor in the collapse, " said Arup associate director Dr Barbara Lane.
We have carried out computer simulations which show that the towers would have collapsed after a major fire on three floors at once, even with fireproofing in place and without any damage from plane impact." Lane said the difference of opinion was significant because clients had begun to demand that designs had NIST-compliant fire protection (NCE 30 June).
NIST is now recommending that all structural elements of tall buildings have the same degree of fire protection.
Firms like Arup have developed international reputations for producing designs which avoid the need for such extensive fi re protection.
Lane commended NIST's modelling exercise and agreed with most of its recommendations.
"But they have not taken proper account of the thermal expansion of the structural elements, especially the floors.
"As a result, there is too much emphasis on passive fire protection in NIST's recommendations and not enough on the benefits of good design." Dave Parker, Gaithersburg (See analysis p23) . ST's report into the baffling collapse of the 47 storey WTC7 tower on 9/11 has been delayed again, NIST confirmed last week. A draft for public comment is now not expected until May next year. In June NIST promised that the report would be out by the end of 2005 at the latest. It blames the latest delay on the need to concentrate resources on finalising the report into the twin towers collapse. |
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