|
Back on topic:
Excerpted article:
| quote: |
Why Indeed Did the WTC Buildings Collapse?
by Steven E. Jones {link}
Thirteen Reasons to Challenge Government-sponsored Reports and Investigate the Controlled-demolition Hypothesis
1. Molten Metal: Flowing and in Pools
There are several published observations of molten metal in the basements of all three buildings, WTC 1, 2 (“Twin Towers”) and 7. For example, Dr. Keith Eaton toured Ground Zero and stated in The Structural Engineer,
‘They showed us many fascinating slides’ [Eaton] continued, ‘ranging from molten metal which was still red hot weeks after the event, to 4-inch thick steel plates sheared and bent in the disaster’. (Structural Engineer, September 3, 2002, p. 6; emphasis added.)
The existence of molten metal at Ground Zero was reported by several observers (see first photograph above), including Greg Fuchek:
For six months after Sept. 11, the ground temperature varied between 600 degrees Fahrenheit and 1,500 degrees, sometimes higher. “In the first few weeks, sometimes when a worker would pull a steel beam from the wreckage, the end of the beam would be dripping molten steel,” Fuchek said. (Walsh, 2002)
2. Observed Temperatures around 1000°C and Sulfidation in WTC 7 Steel
One of the relatively few previous peer-reviewed papers relating to the WTC collapses provides "An Initial Microstructural Analysis of A36 Steel from WTC Building 7." This brief but important letter states:
While the exact location of this beam could not be determined, the unexpected erosion of the steel found in this beam warranted a study of microstructural changes that occurred in this steel. Examination of other sections in this beam is underway.
ANALYSIS Rapid deterioration of the steel was a result of heating with oxidation in combination with intergranular melting due to the presence of sulfur. The formation of the eutectic mixture of iron oxide and iron sulfide lowers the temperature at which liquid can form in this steel. This strongly suggests that the temperatures in this region of the steel beam approached ~1000°C by a process similar to making a “blacksmith’s weld” in a hand forge. (Barnett, 2001)
3. Near-Symmetrical Collapse of WTC 7
As you observed (link above), WTC 7 collapsed rapidly and nearly-straight-down symmetrically -- even though fires were randomly scattered in the building. WTC 7 fell about seven hours after the Towers collapsed, even though no major persistent fires were visible (considerable dark smoke was seen). There were twenty-four huge steel support columns inside WTC 7 as well as huge trusses, arranged non-symmetrically, along with some fifty-seven perimeter columns, as indicated in the diagram below (FEMA, 2002, chapter 5; NIST, 2005).
4. No Previous Skyscraper Complete Collapse Due to Fires
A New York Times article entitled “Engineers are baffled over the collapse of 7 WTC; Steel members have been partly evaporated,” provides relevant data.
Experts said no building like it [WTC7], a modern, steel-reinforced high-rise, had ever collapsed because of an uncontrolled fire. (Glanz, 2001; emphasis added.)
Fire engineering expert Norman Glover agrees:
Almost all large buildings will be the location for a major fire in their useful life. No major high-rise building has ever collapsed from fire…
The WTC [itself] was the location for such a fire in 1975; however, the building survived with minor damage and was repaired and returned to service.” (Glover, 2002)
5. Squib-timing during the Collapse of WTC 7
Horizontal puffs of smoke and debris are observed emerging from WTC-7 on upper floors, in regular sequence, just as the building starts to collapse. (The reader may wish to view the close-up video clip again.) The upper floors have evidently not moved relative to one another yet, from what one can observe from the videos. In addition, the timing between the puffs is less than 0.2 seconds so air-expulsion due to collapsing floors (see Chertoff, 2005) is evidently excluded. Free-fall time for a floor to fall down to the next floor is significantly longer than 0.2 seconds: the equation for free fall, y = ½ gt2, yields a little over 0.6 seconds, as this is near the initiation of the collapse.
6. Early Drop of North Tower Antenna
The official FEMA 9-11 report admits a striking anomaly regarding the North Tower collapse:
Review of videotape recordings of the collapse taken from various angles indicates that the transmission tower on top of the structure began to move downward and laterally slightly before movement was evident at the exterior wall. This suggests that collapse began with one or more failures in the central core area of the building. (FEMA, 2002, chapter 2; emphasis added.)
7. Eyewitness Accounts of Flashes and Loud Explosions
Multiple loud explosions in rapid sequence were heard and reported by numerous observers in and near the WTC Towers, consistent with explosive demolition. Firemen and others described flashes and explosions in upper floors near where the plane entered, and in lower floors of WTC 2 just prior to its collapse, far below the region where the plane had struck the tower (Dwyer, 2005). For instance, at the start of the collapse of the South Tower a Fox News anchor reported:
There is an explosion at the base of the building… white smoke from the bottom… something happened at the base of the building! Then another explosion.” (De Grand Pre, 2002, emphasis added.)
Firefighter Edward Cachia independently reported:
[We] thought there was like an internal detonation, explosives, because it went in succession, boom, boom, boom, boom, and then the tower came down…It actually gave at a lower floor, not the floor where the plane hit. (Dwyer, 2005; emphasis added.)
8. Ejection of Steel Beams and Debris-plumes from the Towers
The horizontal ejection of structural steel members for hundreds of feet and the pulverization of concrete to flour-like powder, observed clearly in the collapses of the WTC towers, provide further evidence for the use of explosives – as well-explained in http://911research.wtc7.net/talks/towers/index.html. (See also, Griffin, 2004, chapter 2.) The observed plumes or "squibs" are far below the pulverization region and therefore deserving of particular attention. They appear much like the plumes observed in http://www.implosionworld.com/cinema.htm (e.g., the controlled demolition of the Southwark Towers).
Unlike WTC7, the twin towers appear to have been exploded “top-down” rather than proceeding from the bottom – which is unusual for controlled demolition but clearly possible, depending on the order in which explosives are detonated. That is, explosives may have been placed on higher floors of the towers and exploded via radio signals so as to have early explosions near the region where the plane entered the tower. Certainly this hypothesis ought to be seriously considered in an independent investigation using all available data.
9. Rapid Collapses and Conservation of Momentum and Energy
The NIST team fairly admits that their report “does not actually include the structural behavior of the tower after the conditions for collapse initiation were reached.” (NIST, 2005, p. 80, fn. 12; emphasis added.) Quite a confession, since much of the external evidence for explosive demolition typically comes after collapse initiation, as seen in cases of acknowledged controlled demolition. (Harris, 2000.) The NIST report could be called the official "pre-collapse theory."
10. Controlled Demolition “Implosions” Require Skill
The occurrence of nearly symmetrical, straight-down and complete collapses of the WTC 7 and the Towers is particularly upsetting to the “official” theory that random fires plus damage caused all these collapses. Even with high-level cutting charges, achieving such results requires a great deal of pre-planning and expertise. As Tom Harris, an authority in this field, has explained:
The main challenge in bringing a building down is controlling which way it falls. Ideally, a blasting crew will be able to tumble the building over on one side, into a parking lot or other open area. This sort of blast is the easiest to execute. Tipping a building over is something like felling a tree. To topple the building to the north, the blasters detonate explosives on the north side of the building first…
Sometimes, though, a building is surrounded by structures that must be preserved. In this case, the blasters proceed with a true implosion, demolishing the building so that it collapses straight down into its own footprint (the total area at the base of the building). This feat requires such skill that only a handful of demolition companies in the world will attempt it.
Blasters approach each project a little differently... [A good] option is to detonate the columns at the center of the building before the other columns so that the building's sides fall inward.... Generally speaking, blasters will explode the major support columns on the lower floors first and then a few upper stories… [nb: The upper floors then fall as a tamper, resulting in “progressive collapse”-- this is common in controlled demolition.] (Harris, 2000; emphasis added.)
11. Steel Column Temperatures of 800°C Needed: A Problem in the Argument of Bazant and Zhou
A Mechanical Engineering professor suggested that I review a paper by Zedenek P. Bazant and Yong Zhou, which I did. Quoting:
The 110-story towers of the World Trade Center were designed to withstand as a whole the forces caused by a horizontal impact of a large commercial aircraft. So why did a total collapse occur? (Bazant and Zhou, 2002, p. 2.)
Correct – the WTC Towers were designed to withstand forces caused by large commercial aircraft – we can agree on that. MIT’s Thomas Eagar also concurs “because the number of columns lost on the initial impact was not large and the loads were shifted to remaining columns in this highly redundant structure” (Eagar and Musso, 2001).
We continue with Bazant & Zhou:
The conflagration, caused by the aircraft fuel spilled into the structure, causes the steel of the columns to be exposed to sustained temperatures apparently exceeding 800oC… (Bazant and Zhou, 2002, p. 2.)
But here we note from the recent NIST report that: “The initial jet fuel fires themselves lasted at most a few minutes” and office material fires would burn out within about 20 minutes in a given location. (NIST, 2005; p. 179, emphasis added.) Certainly jet fuel burning was not enough to raise steel to sustained temperatures above 800oC. But we continue:
Once more than half of the columns in the critical floor.. suffer buckling (stage 3), the weight of the upper part of the structure above this floor can no longer be supported, and so the upper part starts falling down onto the lower part below…”(Bazant and Zhou, 2002, p. 2.)
Bazant & Zhou do not explain how “more than half of the columns in the critical floor [can] suffer buckling” at the same time to precipitate the complete and nearly symmetrical collapse observed. There were 47 huge steel core columns in each Tower, and 24 such support columns in WTC 7 (NIST 2005; NISTb, 2005).
12. Problems in the NIST Report: Inadequate Steel Temperatures and Tweaked Models
I have read through the hundreds of pages of the Final NIST report on the collapses of the WTC Towers. (NIST, 2005) It is interesting to note that NIST “decoupled” and delayed their final report on WTC 7, which is overdue as of this writing (NIST, 2005; NISTb, 2005). I agree with some of the NIST report; for example:
Both WTC 1 and WTC 2 were stable after the aircraft impact, standing for 102 min and 56 min, respectively. The global analyses with structural impact damage showed that both towers had considerable reserve capacity. This was confirmed by analysis of the post-impact vibration of WTC 2… where the damaged tower oscillated at a period nearly equal to the first mode period calculated for the undamaged structure. (NIST, 2005, p. 144; emphasis added.)
At any given location, the duration of [air, not steel] temperatures near 1,000oC was about 15 min to 20 min. The rest of the time, the calculated temperatures were near 500oC or below.” (NIST, 2005, p. 127, emphasis added.)
NIST contracted with Underwriters Laboratories, Inc. to conduct tests to obtain information on the fire endurance of trusses like those in the WTC towers… All four test specimens sustained the maximum design load for approximately 2 hours without collapsing.” (NIST, 2005, p. 140, emphasis added.)
13. NIST's Failure to Show Visualizations
An article in the journal New Civil Engineering (NCE) lends support to concerns about the NIST analysis of the WTC collapses. It states:
World Trade Center disaster investigators [at NIST] are refusing to show computer visualizations of the collapse of the Twin Towers despite calls from leading structural and fire engineers, NCE has learned. Visualisations of collapse mechanisms are routinely used to validate the type of finite element analysis model used by the [NIST] investigators. The collapse mechanism and the role played by the hat truss at the top of the tower has been the focus of debate since the US National Institute of Standards & Technology (NIST) published its findings….
University of Manchester [U.K.] professor of structural engineering Colin Bailey said there was a lot to be gained from visualising the structural response. “NIST should really show the visualisations; otherwise the opportunity to correlate them back to the video evidence and identify any errors in the modeling will be lost,” he said….
A leading US structural engineer said NIST had obviously devoted enormous resources to the development of the impact and fire models. “By comparison the global structural model is not as sophisticated,” he said. “The software used [by NIST] has been pushed to new limits, and there have been a lot of simplifications, extrapolations and judgment calls.” (Parker, 2005; emphasis added.)
Here we have serious concerns about the NIST WTC collapse report raised by structural and fire engineers, augmenting the arguments raised here by a physicist.
The thirteen points above provide scientific data and analyses that support my call for an immediate investigation of 9/11 events, while challenging the official story. A few other considerations provide further motivation for the proposed urgent investigation. |
___________________
Last edited by ogvh5150 on Aug-28-2006 at 23:35
|
