where is Osama?

[Benny2guns]

the towers.

each floor only supports a the floor above it and a bit more.
its a bit like on the american football field. one player after another jumps on the quarter back, each player supports the next. you drop all that weight at once on the quarter back and he's crushed.
the same happened with the towers. the plane hit. stripped some of the steel of their fire protection. the jet fuel burnt for a short while and the steel while not melting warped. as soon as the steel warped even a fraction. the weight of the floor above it grew exponentially to the weight of the whole building about it. like the buttress of a cathedral the weight of the roof travels down through the buttress and in doing so is fully supported. twist of move the buttress and the roof collapses.

the steel on each floor allows the weight of the floor above it to flow downward. the weight isn't trying to push the steal sideways, it's impossible for it to do so. but once the steel is warped which is what happens if it get red hot. (steel will glow red hot at 600 degrees or even less. ) put a knife over a a calor or propane gas flame and see for yourself. (gas burns at about 600 degrees. try it and see) it will turn cherry red. in this state the metal is liable to bend and fold under excessive weight. once it does bend, even fractionally the weight above has more force. the weight above now has movement as an added force (velocity) because of this added velocity the weight grows.

example. a fist weighs 1 kilo if you move it fast enough it can have over 400 kilo of weight, the bigger the mass the less velocity it needs to have a lot bigger force. just moving at an inch an hour the weight of the building would have a tremendous amount of extra energy.

i think it was traveling much faster than that. so on one or two floors the steel got hot (didn't melt) and warped. after that it couldn't support what was above it. as for windows popping out as if they were exploding before the collapse got to that floor; air pressure. the pressure in the floors below the falling floors would have had a tremendous pressure exerted upon them. it would make no difference if every door was locked and bolted. they would have been blown off like matchwood. the resulting pressure wave for so much weight would have been huge.
the collapse of the building started slow. then it pick up speed as each successive floor collapsed. that it they fell was inevitable.

build a pyramid of cards and take one out, the pyramid collapses.

stand an egg on it end and you can stand on it. move it off center a fraction and it breaks .
but a board with a 100 nails on someones back and you can stand on it without injuring him. do the same thing with two or four nails and he's dead lmao.

it all boils down to stresses. it has little to do with melting or not melting.

if you simply heat steel and them it cools rapidly it becomes brittle. you effectively turn the steel into cast iron.
and sideways movement and it will break at the height that building was with the floor of windows blown out, the cooling would be very quick. again a building of that height has sideways movement. couple that with warped steel and the momentum of the upper floors and it would be a miracle if it didn't collapse. and not i have no links.

i don't need one to prove steel glows red hot at less than 600 degrees.
i don't need one to show that metal at 600 degrees can bend or warp under a small amount of weight ( it's why they fireproof them) if as you say they can withstand any heat higher than can be generated, why do they fire proof them?

i don't need a link about mass and momentum
i don't need a link about pressure waves and there existence from a collapsing mass.

i don't need them because these things are all fact.

i think they fell because the plane hit them.

What you say makes a little sense to me but I don't think it happened that way for the simple reason that it has already been proven that it could and did not. Don't get me wrong as I really wish someone could prove the planes did bring them down but in reality they can not do so. I know a bit about steel myself and those beams were massive. we are not talking about your avarage 12 inch x 12 inch x 5/8 inch steel beams here, lol. I had used stell to build most of my life. I use oxy/accetl to heat and cut it with. You still have to heat them all evenly and at the correct spot to even begin to imagine this sort of senario happening. It would be pure fluke if one building came down straight into itself like that let alone 3 of them and from only 2 strikes. It is just way to far past what I can grasp as non fiction. There have been other fires way worse than the towers that caused no such destruction. I could have had no problem with the part above what was hit with the plane droping to one side and then some how bringing the building down but in no way straight down.
Proofs of Demolition
Demolition of the Twin Towers is Provable Through Simple Analysis
Despite the destruction of the most significant evidence of the Twin Tower collapses -- the structural steel -- it is relatively easy to prove the towers were demolished. Determining how they were demolished without the benefit of the steel may be difficult or impossible, but proving that a gravity-driven collapse is insufficient to explain the characteristics of the collapses documented by photographic and seismic evidence is not.

There are numerous pieces of evidence that strongly indicate demolition, including the fact that authorities destroyed and suppressed evidence, the more than 100 years of engineering experience with steel-frame buildings, the misleading representation of the towers' design by truss theory proponents and the implausible sequence of events proposed by that theory, and the many collapse features that seem irreconcilable with gravity-driven collapses.

Proving demolition requires more than enumerating evidence. It requires making logical inferences about events using the evidence. Three fairly strong proofs are as follows. These are presented as qualitative arguments only. Each suggests an approach for developing a rigorous quantitative proof.

The towers fell faster than they could have if they were crushing themselves.
The volume of dust was too great to have been the product of a gravity-driven collapse.
The South Tower's top shattered before falling, and so its breakup was not a result of gravity-driven crushing.


Speed of Fall
Twin Towers' Rates of Fall Proves Demolition
Each of the Twin Towers fell completely in intervals of time similar to that taken for a block of wood dropped from a tower's roof to reach the ground. A block of wood has about the same average density as the main components of the towers near their tops.

In a vacuum, a block of wood (or lead) would take 9.2 seconds to fall from the tower's roof. In the air a block of wood, say ten inches on a side, might take 50 percent longer than in a vacuum. Fifteen seconds, a good estimate for the total time of collapse of the North Tower, is about the time it would take our block to fall from the roof. The rubble from the Tower probably had similar average density to our block of wood, since the floor slabs consisted of corrugated sheet metal and lightweight concrete, and the perimeter steel columns were hollow with walls only 1/4th inch thick at the Towers' tops. Air resistance alone could account for the slowing of the falls to the point where each Tower took about 15 seconds to completely come down.

The official story requires that more than air resistance was slowing the descents. The falling rubble would be having to crush every story below the crash zone -- ripping apart the steel grids of the outer walls and obliterating the steel lattice of the core structure. The resistance of the intact building itself would be thousands of times greater than air resistance.

If air resistance is able to increase total collapse times by even 20 percent, then shouldn't the addition of the resistance of the buildings themselves increase the time several thousand percent, to at least tens of minutes?

Of course the idea of a collapse lasting minutes is absurd. So is the idea of a steel frame building crushing itself.
Volume of Dust
Volume of Dust Clouds Proves Demolition
Both of the Twin Towers exploded into vast clouds of dust. That the clouds expanded to five times the volume of the towers within 30 seconds of the initiation of their collapses is a conservative estimate.

If the collapses were merely gravity-driven, then any clouds of debris produced in the immediate aftermath should have occupied about the same amount of space as the intact towers before they had time to significantly mix into the surrounding air. The bulk of the clouds could only come from the expulsion of gases in the buildings as they collapsed, and the mixing of ambient air into the clouds. The contribution of mixing increases over time, and is unbounded. However, the dust clouds appear to expand more rapidly than can be accounted for by mixing. This implies that heat energy was being added to the clouds in order to cause the gases to expand, and/or water to vaporize.

Could the known energy sources have accounted for the pre-mixing expansion? This question is treated in some quantitative detail in the paper: The North Tower's Dust Cloud: Analysis of Energy Requirements for the Expansion of the Dust Cloud Following the Collapse of 1 World Trade Center. This paper estimates the dust cloud volume of the North Tower and shows that, even allowing for expansion due to mixing, the heat sink is many times greater than the tower's gravitational energy. Even without such quantitative analysis, it is clear that the gravitational energy of the towers alone could not have driven the dust clouds' expansion, given limitations on conversion of that energy to heat and the apparent absence of extensive mixing early in the clouds' development.

The expansion of the dust clouds presents problems for the gravity collapse theory that are evident without quantitative analysis. Here we consider the role of the two main factors that could have worked to expand the dust clouds.

Heating of the air due to friction of the collapse
Mixing of the cloud's gases and suspended solids with ambient air

Did Friction Multiply the Clouds' Volumes?
Suppose that nearly all of the gravitational energy of the towers was converted into friction and therefore heat. Would that have been sufficient to expand the dust clouds? A clue is that in a typical demolition, the volume of the dust cloud grows to only slightly larger than the intact building's volume immediately following the collapse. Even if the gravitational potential energy of the towers was great enough to drive the expansion, it is highly doubtful that much of it would be converted into heat in the dust clouds, for several reasons.

Rubble falling through the air would not generate much heat energy until it hit the ground, and then most of the energy would be converted to ground movement and the finer breakup of the rubble rather than heat.
Rubble crushing the building would convert much of its kinetic energy to friction in the steel frame in the process of shredding it. The steel frame would not have enough surface area to transfer much heat to the gases during the split second in which the building around any given piece of steel was crushed, so most of the heat would have ended up in the rubble pile.
If much of the gravitational energy was converted to heat through friction, it would have necessitated longer collapse times than were observed.
At least one academic paper has attempted to explain the rapidity of the collapses by promoting a questionably applicable mathematical model alleged to predict a nearly frictionless total collapse. Since that model has each tower neatly pulling itself down at near the speed of free-fall, there would be very little heat produced to drive the dust cloud expansion.

Did Mixing Expand the Clouds?
Mixing of building air with ambient air could not account for the rapidity of the expansion of the dust clouds, nor their appearance. Mixing of gases can occur through diffusion or convection. Diffusion is not relevant, since it is the space occupied by suspended particles that defines the volume of the cloud. Convection could only expand the cloud if there was a high degree of turbulence on the cloud's boundary, and would have produced a diffuse boundary. That does not appear to have occurred in the early stages of the Twin Towers' dust clouds. The clouds maintained well-defined interfaces as they expanded to many times the buildings' volumes. Moreover, features on the surface of the clouds evolved slowly relative to the movement of large portions of the cloud. The distinct boundaries and persistent shapes mean the clouds were expanding primarily by pushing aside the ambient air, not by assimilating it.
Breakup of WTC 2's Top
Shattering of South Tower's Top Proves Demolition
There are several pieces of evidence that show the structure of the 30 stories of the South Tower above the impact zone was shattered before it started its precipitous plunge. How could the steel frame of many stories above the impact zone have broken up even before it started to fall? The proponents of gravity-driven collapse maintain that the tops of the towers crushed the floors below the impact zones as they fell. The tops functioned as pistons, according to Bazant and Zhou, crushing the stories one by one. What one actually sees in the case of the South Tower is that their piston disintegrated even before it started to fall. A gravity-driven collapse cannot account for that disintegration, nor for how a cloud of rubble could crush the intact structure below the impact zone.


These frames from a South Tower collapse video are separated by equal time intervals. Examining the middle edge of the falling portion of the tower shows that its angle of tilt from vertical remains about the same between the second and third frames, and therefore the top has stopped rotating. But unless the top had already been shattered, it should have continued to rotate in accordance with the law of conservation of angular momentum.
Collapse Theories
Theories Gravity Caused the Twin Towers to Crush Themselves
The official story of the collapse of the Twin Towers is that gravity caused them to crush themselves. The impacts and fires weakened the buildings near the the crash zones but it was gravity that did the work of demolishing them. There are principally two official theories:

The column failure theory
The truss failure theory
Both theories are frequently called pancake theories because the pancake metaphor subtly suggests the buildings consisted primarily of heavy floor slabs, not vertical pillars of steel. Variants of the column failure theory were the first out of the block. They ask us to believe that all of the columns on one level suddenly failed, causing the overhanging portion of the tower to fall at least a floor, thereby acquiring enough momentum to crush the intact portion of the tower, floor-by-floor.

The column failure theory would suffice for scientific papers and insurance claims, but the American public would require something less obviously inconsistent with the reality that the columns of entire floors were not glowing red-hot. Hence the truss failure theory was presented on popular science shows, and endorsed by FEMA's official report. It asks us to believe that the fires weakened floor trusses, causing a whole floor diaphragm to fall, initiating a chain reaction of floor failures. That is supposed to lead to the collapse of the perimeter walls and core structures, an idea made more palatable by hiding the towers' core structures, or misrepresenting them as mechanically unsubstantial.

Progressive Collapse
The experts gave us the cool-sounding progressive collapse to help sell the collapse theories, whether they emphasize falling floors or buckling columns. But does it apply to steel structures? Some structures do fall apart under their own weight if sufficiently weakened or disturbed, such as burned wood-frame houses, or earthquake-fractured masonry buildings. Steel structures are not known to, outside of rare cases, but perhaps they could be designed to. Getting a steel structure to crumble from the top down -- as in the alleged progressive collapse phenomenon -- is an even greater challenge.

Not only is top-down progressive collapse completely unknown in other steel structures, we know of no documented case of it using any materials. Hence we have created the progressive collapse challenge. We believe the first two challenges are possible. Some variant of the following construction may work.

Construct a tower by balancing thin cylinders upright in rows around the perimeter of a square plate. Balance a second plate on the tops of the cylinders, and arrange similar rows of cylinders on it. Repeat this arrangement of alternating plates and cylinders for the height of the tower.
If such a structure were disturbed near the top, it could come tumbling down, and the collapse just might start at the zone of the disturbance and progress downward.

Other Theories
In addition to the officially endorsed column failure and truss failure theories, other theories have been volunteered to explain the explosive disintegration of the towers, while also ignoring or denying demolition. Some of these are identified in a taxonomy of collapse theories.