Dans la plupart des rapport d’expertise, les ingénieurs et les architectes consultés estiment que les étages supérieurs de chacune des deux constructions ont cédé au moment où leurs structures en acier ont commencé à fondre sous l’effet des incendies.
 
« C’est la force de la gravitation qui a finalement vaincu la résistance de la structure », déclare Jon Magnusson, ingénieur et directeur du Skilling Ward Magnusson Barkshire, une firme de Seattle (Etat de Washington), spécialisée dans l’architecture des tours et constructions en hauteur. « Lorsque les derniers niveaux ont commencé à s’effondrer, ils ont brutalement pesé sur les niveaux directement inférieurs, ajoutant la force de l’impact à leur propre poids. Il s’en est suivi une véritable réaction en chaîne, dans laquelle non seulement le poids, mais aussi la vitesse augmentait rapidement. Aucune structure ne pouvait résister à cela, aussi robuste soit-elle. Mais c’est le feu, » ajoute-t-il, « qui a permis à la gravité de finalement l’emporter contre la résistance intrinsèque des deux tours. »
 

Cette violente secousse a largement contribué non seulement à la destruction des Twin Towers, mais aussi à la fragilisation des immeubles voisins et au soulèvement d’un abondant nuage de débris et de poussières.
 

L'American Society of Civil Engineers (ASCE), conjointement avec la Federal Emergency Management Agency (FEMA), a mis sur pied une équipe d'experts (Building Performance Assessment Team) pour évaluer la performance des bâtiments dans le but, précisément, d'étudier les facteurs qui ont conduit à l'effondrement des tours du World Trade Center et d'autres bâtiments voisins .
 
Cette équipe, qui est composée de spécialistes des gratte-ciel, des structures d'acier, des connexions, des techniques de prévention des incendies, de l'effet de souffle et des études structurales, identifiera et recommandera aussi d'autres avenues de recherche suite à ces attaques terroristes.
 

L'équipe BPAT réunit des chefs de file du génie du bâtiment sous la direction de l'ASCE et de la FEMA et comprend également les organismes suivants : l'American Institute of Steel Construction Inc. (AISC), l'American Concrete Institute (ACI), le Council on Tall Buildings and Urban Habitat (CTBUH), l'International Code Council (ICC), la National Fire Protection Association (NFPA), la Society of Fire Protection Engineers (SFPE), la Structural Engineers Association of New York (SEAoNY), la Masonry Society (TMS), le National Council of Structural Engineers Associations (NCSEA), le Structural Engineering Institute (SEI) de l'ASC, et le Department of Design and Construction (DDC) de New York.

Fire Engineers Call WTC Probe ‘Half-Baked Farce’
 
A respected professional magazine read by firefighters and engineers is calling the investigation into the collapse of the World Trade Towers a farce and a sham.

NAUDET, Jules & Gideon
French cameramen. They videod the north tower hit, and also damage to the north tower lobby damage. For the lobby damage, see
st12.startlogic.com/~xenonpup/underground/underground_explosions.htm (scroll down, with video). Comment on that page:
”The narrator claims that he ‘later learned’ that there had been an explosion caused by fuel pouring down an elevator shaft, but the lobby shows none of the soot or fuel residue we would expect from such an explosion.  Instead we see blown-out windows and a fine dry dust covering the entire lobby, very much the signature of high explosives.  Similar damage to the parking garages and subbasements can only be explained by pre-placed explosive charges that were detonated at the moment of the plane’s impact.”
Direct link to the video:
st12.startlogic.com/~xenonpup/underground/lobby.mpg  
I remember reading that in WTC1 there was no single elevator shaft that ran from the lobby directly to the 90th floor levels where the flying object hit. You had to transfer to another elevator along the way. I doubt that fuel could have charged through the building like this. Confirmed by George S. PHEONIX,
http://www.littlewhitedog.com/content-16.html

PECORARO, Mike, & DELBIANCO, Arti
Mike Pecoraro, on 9-11-1, a resident of Long Island, a Stationary Engineer in the World Trade Center (north tower). Arti Delbianco, a co-worker of Pecoraro.
Witnesses to at least one underground explosion under the World Trade Center in the morning of 9-11-1. Their story has been covered in a long article in the power engineering and real estate management magazine „Chief Engineer”,
www.chiefengineer.org/article.cfm?seqnum1=1029[.;;]„We smelled kerosene,“ Mike recalled, „I was thinking maybe a car fire was upstairs“, referring to the parking garage located below grade in the tower but above the deep space where they were working  
 
The two decided to ascend the stairs to the C level, to a small machine shop where Vito Deleo and David Williams were supposed to be working. When the two arrived at the C level, they found the machine shop gone.
 
„There was nothing there but rubble, „Mike said. „We’re talking about a 50 ton hydraulic press ? gone!“ The two began yelling for their coworkers, but there was no answer. They saw a perfect line of smoke streaming through the air. „You could stand here,“ he said, „and two inches over you couldn’t breathe. We couldn’t see through the smoke so we started screaming.“ But there was still no answer.  
 
The two made their way to the parking garage, but found that it, too, was gone. „There were no walls, there was rubble on the floor, and you can’t see anything“ he said. They decided to ascend two more levels to the building’s lobby. As they ascended to the B Level, one floor above, they were astonished to see a steel and concrete fire door that weighed about 300 pounds, wrinkled up „like a piece of aluminum foil“ and lying on the floor. „They got us again,“ Mike told his co-worker, referring to the terrorist attack at the center in 1993. Having been through that bombing, Mike recalled seeing similar things happen to the building’s structure. He was convinced a bomb had gone off in the building. Mike walked through the open doorway and found two people lying on the floor. One was a female Carpenter and the other an Elevator Operator. They were both badly burned and injured. Realizing he had to get help, Mike ascended to the Lobby Level where he met Arti DELBIANCO, a member of his work crew.  

WTC "INVESTIGATION"?: A CALL TO ACTION
...
The World Trade Center disaster was
* The largest loss of firefighters ever at one incident.
* The second largest loss of life on American soil.
* The first total collapse of a high-rise during a fire in United States history.
* The largest structural collapse in recorded history.  
 
Now, with that understanding, you would think we would have the largest fire investigation in world history. You would be wrong. Instead, we have a series of unconnected and uncoordinated superficial inquiries. No comprehensive "Presidential Blue Ribbon Commission." No top-notch National Transportation Safety Board-like response. Ironically, we will probably gain more detailed information about the destruction of the planes than we will about the destruction of the towers. We are literally treating the steel removed from the site like garbage, not like crucial fire scene evidence.
 
The World Trade Center disaster demands the most comprehensive detailed investigation possible. No event in our entire fire service history has ever come close to the magnitude of this incident.
 
We, the undersigned, call on FEMA to immediately impanel a "World Trade Center Disaster Review Panel" to coordinate a complete review of all aspects of the World Trade Center incident.
 
The panel should be charged with creating a comprehensive report that examines a variety of topics including determining exactly how and why the towers collapsed, critiquing the building evacuation procedures and the means of egress, assessing the buildings' fire protection features (steel "fireproofing," fire protection systems, etc.), and reviewing the valiant firefighting procedures employed. In addition, the Panel should be charged with preparing a detailed set of recommendations, including the critical changes necessary to our building codes.

Hermann Goering, procès de Nuremberg (45-46). (Source : Le système totalitaire, Hannah Arendt, 1951)
"Naturellement les gens ne veulent pas la guerre ; mais après tout ce sont les dirigeants d’un pays qui déterminent la politique. C’est facile ensuite d’entraîner le peuple, qu’il dispose de la liberté d’expression ou pas ; on peut amener le peuple où l’on veut et lui faire faire ce que veulent les dirigeants. C’est très facile : il suffit de leur dire qu’ils sont en train d’être attaqués et de dénoncer les pacifistes pour leur manque de patriotisme qui met le pays en danger. Ça fonctionne de la même façon dans tous les pays."

notre *capacité* à émettre des jugements erronés.

Fougnac a écrit:
Maintenant ta citation de Goering, tu peux l'utiliser, vas-y, fais toi plaisir.

Après le 11 Septembre, je me suis engagé auprès du peuple américain:
 cette nation n'attendra pas d'être attaquée à nouveau.
In http://www.whitehouse.gov/news/rel [...] 628-7.html
 
Goering à Nuremberg en 1946:
il suffit de leur dire qu’ils sont en train d’être attaqués

Rappel de la citation de Goering:
Hermann Goering, procès de Nuremberg (45-46). (Source : Le système totalitaire, Hannah Arendt, 1951)  
"Naturellement les gens ne veulent pas la guerre ; mais après tout ce sont les dirigeants d’un pays qui déterminent la politique. C’est facile ensuite d’entraîner le peuple, qu’il dispose de la liberté d’expression ou pas ; on peut amener le peuple où l’on veut et lui faire faire ce que veulent les dirigeants. C’est très facile : il suffit de leur dire qu’ils sont en train d’être attaqués et de dénoncer les pacifistes pour leur manque de patriotisme qui met le pays en danger. Ça fonctionne de la même façon dans tous les pays."