Quote:Dazed by the news,the American public soon believed the fires in the towers had burned so hot they caused the steel frames of the buldings to give way.A myth developed,fed by official sources through the media to a bewildered audience.

Elements of the myth: The impact of the airplanes,gallons of burning jet fuel,steel melting,the buildings failing and suddenly imploding.In a mere 10 seconds,110 stories hurtled earthward, pulverizing into dust.

Right from the start,on the street itself,the official story was born.

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Quote:The myth bled into the FEMA report and was echoed by the experts

Textual: the structural damage sustained by each tower from the impact,combined with the ensuing fires resulted in total collapse of each building.As the towers collapsed, massive debris clouds consisting of....

Quote:"It was the combination of the impact load doing great damage to the building followed by the fire,that caused collapse.

-W. Gene Corley,Ph D. American Society of Civil Engineers

Quote:John Skilling and Les Robertson were the structural engineers who designed the streamlined steelframes of the twin towers in the 1960's


Because a wayward bomber flew into the Empire State Building in 1945,the towers were built with skyscrapper crashes in mind.The airplane we were envisioning was the largest airplane of its time(B-29???),flying slowly and low,lost in the fog,we designed the buildings to take the impact of the Boeing 707,hitting the building at any location.

[""""Oficial Story""""] But the aircraft that hit the towers was a boeing 767,heavier than a 707,fueled for a transcontinental flight and travelling fast" - 707 and 767 are comparable.The maximum take off weight of a fully loaded 707 is almost 334000 pounds.As airplanes only carry the fuel load they need,the smaller-model 767s that struck the towers were not,in actuality,maximally fueled.

Quote:But the CD theorists consistently overlook two factors here. Firstly that the designers had in mind an aircraft coming in to land at New York airport, at speeds of around 180 mph (according to the FEMA report, page 1:17). But the aircraft hit the towers at an average of nearly three times that speed. Given that the impact damage hinges on the kinetic energy of the projectile, which rises with the square of speed, the planes hit the Twin Towers with nearly nine times the impact anticipated. (Note that the NIST report - on page 6 - contradicts this argument by stating that the Towers were designed for a 600 mph impact. I would be pleased to hear from anyone who can settle this discrepancy one way or the other.) Secondly, design is an art not a science: the Titanic was designed not to sink; the space shuttle was designed not to explode on takeoff, and designed not to break up on re-entry. Etc

Quote:As for the heat of the fires,listen to the radio communications of these NYC Firemen:

(Grabacion)
"Ladder 15,we've got two isolated pockets of fire.We should be able to knock it down with two lines.Radio that,78 th floor".

Isolated pockets of fire.Two water lines to knock them down.FEMA executive summary relays that much of the fuel in the planes(jet graded kerosene) was consumed by the initial fireballs

Quote:9:25 a.m.

Ladder 15: "Go ahead, Irons."

Ladder 15 Irons: "Just got a report from the director of Morgan Stanley. Seventy-eight seems to have taken the brunt of this stuff, there's a lot of bodies, they say the stairway is clear all the way up, though."

9:52 a.m.

Battalion Seven Chief: "Battalion Seven to Battalion Seven Alpha."

"Freddie, come on over. Freddie, come on over by us."

Battalion Seven Chief: "Battalion Seven ... Ladder 15, we've got two isolated pockets of fire. We should be able to knock it down with two lines. Radio that, 78th floor numerous 10-45 Code Ones."
Ladder 15: "What stair are you in, Orio?"

Battalion Seven Aide: "Seven Alpha to lobby command post."

Ladder Fifteen: "Fifteen to Battalion Seven."

Battalion Seven Chief: "... Ladder 15."

Ladder 15: "Chief, what stair you in?"

Battalion Seven Chief: "South stairway Adam, South Tower."

larean Wrote:No he visto Loose Change, pero los argumentos son definitivamente similares a los de todo conspiracionista: citas fuera de contexto, postulados equivocados sobre cuestiones científicas... En efecto, no es necesario que el acero se funda. A una fracción de la temperatura de fusión (que no tengo a mano ahora mismo) pierde rápidamente su resistencia a los esfuerzos de tensión y torsión. Eso es probablemente lo que sucedió.

Quote:“However,if we take a closer look of the how the buildings collapsed,it appears as if explosives were used. For example,dust shot out from a few windows far below the collapsing area.”

Quote:Matt Komorowski: “The first thing I really felt was the incredible rush of air at my back. And maybe I felt it before everybody else, because I was the last guy.”
Stone Phillips: “Like a gust of wind, behind you.”
Matt Komorowski: “Gust of wind. Wind tunnel. It was the most incredible push at your back, that you can feel.”
http://www.acfd.com/miracle_of_ladder_company_6.htm

BILL BUTLER, NEW YORK FIRE DEPARTMENT: We took two steps down from the fourth floor and the building started to shake.

SALVATORE D'AGOSTINO, NEW YORK FIRE DEPARTMENT: You could hear the floors pancaking one on top of the other, huge explosions.

LIM: Boom, boom, boom, boom, boom, and faster as they get closer. What I remember the most was the wind. created almost like a hurricane-type force and actually pushed one of the firemen right by me.
MIKE MELDRUM, NEW YORK FIRE DEPARTMENT: I was flown down a flight of stairs, a little groggy for a while. I noticed somebody on a half landing just up from me, a few stairs and I thought it was one of our guys and it was David Lim.

http://transcripts.cnn.com/TRANSCRIPTS/0209/07/pitn.00.html

Quote:Of course, I expect the conspiracy theorists to say this was just the explosives which caused the high wind ("He even says explosions!") but they have no evidence of explosives. We do have evidence of pancaking. The ejecta coming out of the windows of the pancaking floor was uniform across the floor and light in color. It was coming out of every floor window until the falling debris obscured its view. Controlled demolition has staggered ejecta because the charges are only on some columns. You also always see at least [some] before the collapse and not [only] during it. There are none of these jets of debris before collapse.
Another point is the amount of these so called squibs. Some are laughably small wisps of smoke. I won’t even bother with these. These are people who are searching every video, frame by frame in order to find something which they can use. Some are simply glass falling and reflecting sunlight or a piece of aluminum cladding doing the same. Yet, some seem to be heavy jets out of a window on one floor and another jet of debris about 30 to 40 stories below as the collapse progresses. I have to admit, when I first saw this I didn't know what to make of it. But as I thought of the possibilities, I also thought of what it needed to be if it were a demolition. In all the controlled demolitions I've seen, there have been a large amount of explosives on almost all floors. Even some small buildings have many charges. Why would they put charges on what seems like only a couple of floors? And once the collapse progressed, why would they care about the 40th floor? When the top 70 floors are crashing down on the 40th floor; even conspiracy theorists have trouble believing that floor would stop the collapse. And even if it did, the message is sent. The towers were no longer usable after the top 70 stories fell on it. It would be an added and absurd risk to add explosives on the lower floors.

Quote:We were told that the collapse begun when one floor broke,and the pieces felt to the floor below it.Those pieces caused next floor to go down,and so on the way down”.”However,when the pieces hit the floor below,they would slow down slightly,and some of their energy would be used to break the floor.Therefore,there should be a delay every time the pieces hit a floor.”The towers had 110 floors ,so if it took one second to each floor to be crashed,that would be 110 s.However,seismic data and video shows that north tower collapsed in only 8,4 seconds.The collapse started on floor 94.If you were to throw a rock from floor 94 it would hit the ground about 8.4 seconds later.This means that the pieces of the building were falling down as fast as objects falling through the air.How can objects crash through steel and concrete as fast as they fall through the air?

Quote:As generally accepted by structural engineering and structural mechanics experts (though not by some laymen and fanatics seeking to detect a conspiracy), the failure scenario, broadly proposed by Bazant (2001), and Bazant and Zhou (2002), on the basis of simplified analysis, and supported by very realistic, meticulous and illuminating computer simulations and exhaustive investigations by S. Shyam Sunder's team at the National Institute of Standards and Technology (NIST, 2005), may be summarized as follows:

1. About 60% of the 60 columns of the impacted face of framed-tube (and about 13% of the total of 287 columns) were severed, and many more were significantly deflected. This caused stress redistribution, which significantly increased the load of some columns, near the load capacity for some of them.

2. Fire insulation was stripped during aircraft impact by flying debris (without that, the towers would likely have survived). In consequence, many structural steel members heated up to 600±C (NIST 2005) (the structural steel used loses about 20% of its yield strength already at 300±C, NIST 2005, and exhibits significant visco-plasticity, or creep, above 450±, especially at high stresses that developed; see e.g. Cottrell 1964, p. 299; the press reports right after 9/11, indicating temperature in excess of 800±C, turned out to be groundless, but Bazant and Zhou's analysis did not depend on that).

3. Differential thermal expansion, combined with heat-induced viscoplastic deformation, caused the floor trusses to sag. The sagging trusses pulled the perimeter columns inward (by about 1 m, NIST 2005). The bowing of columns served as a huge imperfection inducing multi-story buckling. The lateral deflections of some columns due to aircraft impact and differential thermal expansion also decreased buckling strength.

4. The combination of six effects

a) overload of some columns due to initial stress redistribution,
b ) lowering of yield limit and creep,
c) lateral deflections of many columns due to sagging floor trusses,
d) weakened lateral support due to reduced in-plane stiffess of sagging floors,
e) multi-story buckling of some columns (for which the critical load is an order of magnitude less than it is for one-story buckling), and
f) local plastic buckling of heated column webs finally led to buckling of columns (Fig. 1b). As a result, the upper part of tower fell, with little resistance, through at least one floor height, impacting the lower part of tower. This triggered progressive collapse because the kinetic energy of the falling upper part far exceeded the energy that could be absorbed by limited plastic deformations and fracturing in the lower part of tower. (Bazant, Verdure, 2006)
http://www.civil.northwestern.edu/people/bazant/PDFs/Papers
/ProgressiveCollapseWTC-6-23-2006.pdf

larean Wrote:No he visto Loose Change, pero los argumentos son definitivamente similares a los de todo conspiracionista: citas fuera de contexto, postulados equivocados sobre cuestiones científicas... En efecto, no es necesario que el acero se funda. A una fracción de la temperatura de fusión (que no tengo a mano ahora mismo) pierde rápidamente su resistencia a los esfuerzos de tensión y torsión. Eso es probablemente lo que sucedió.