The claim is always made that "steel skyscrapers have never collapsed from fire". That has been proven to be a very weak argument. There have been many examples of fire destroying a steel framed building. The TU Delft Architecture school. The entire building didn't collapse, but it wasn't a skyscraper. The taller and the smaller the footprint, the more it compounds the effects of a fire. The Windsor Tower is always used to prove that steel frame building won't collapse due to fire. The only problem is, that the steel frame of that building DID collapse. It is the concrete portion of that building that is still standing.
Can you provide us with evidence that a fire engulfed hi-rise should be expected to fall totally a few seconds short of the time it takes for a billiard ball to drop from its roof line, causing tons of steel and mass to just move out of the way for this to occur in such a short amount of time?
I look forward to your pics and links.
Can you find me evidence of another building, with tube in a tube construction, that was struck by an airliner at high speed? NO.
This unprecedented event is treated like it should have looked like a "typical" building fire.
Again, the Windsor Tower for example, if that building had been ALL steel...............it would have completely collapsed. The concrete portion saved that building. The twin towers had no concrete encased columns.
As for the
"causing tons of steel and mass to just move out of the way for this to occur". I explained on another post that there was no steel and mass that needed to move out of the way. There was no vertical steel "under" those floors. The floors spanned from core to exterior column, with no other support. The floors were being sheared off of the "supporting" mass. The exterior columns falling away and the core standing for a short time after the floors collapsed.
* Steel is a good conductor and concrete is a poor conductor of heat. Thus in a fire, a steel frame will conduct heat away from the hotspots into the larger structure. As long as the fire does not consume the larger structure, this heat conductivity will keep the temperatures of the frame well below the fire temperatures. The same is not true of steel-reinforced-concrete structures, since concrete is not a good thermal conductor, and the thermal conductivity of the rebar inside the concrete is limited by its small mass and the embedding matrix of concrete.
* Fires can cause spalling of concrete, but not of steel. This is because concrete has a small percentage of latent moisture, which is converted to steam by heat. Thus, a large fire can gradually erode a concrete structure to the point of collapse, whereas a fire can only threaten a steel-framed structure if it elevates steel temperatures to such an extent that it causes failures.
The observation that the Windsor Building is the only skyscraper to have suffered even a partial collapse as a result of fire suggests that the use of steel-reinforced-concrete framing was responsible. A closer look at the incident shows reality to be more complex. The portion of the building that collapsed consisted of the outer portions of floor slabs and perimeter walls throughout the upper third of the building (the 21st through 32nd floors).
The outer walls consisted of steel box columns arranged on 1.8 meter centers and connected by narrow spandrel plates. The columns had square cross-sections 120mm on a side, and were fabricated of C-sections 7mm thick welded together.
(these had a fraction of the dimensions, and were spaced about twice as far apart as the perimeter columns of the Twin Towers.)The perimeter columns lacked fireproofing throughout the upper third of the Windsor building.
The Windsor Building fire demonstrates that a huge building-consuming fire, after burning for many hours, can produce the collapse of parts of the building with
weak steel supports lacking fire protection.
It also shows that the collapse events that do occur are gradual and partial.
Again show us an example of a fire causing collapse that produced a TOTAL fall a few seconds short of a free fall collapse.
You cant, after insinuating that this is a common result of fires in hirises in your previous post.
The Windsor building still stood, evidenced by many pictures taken after the very long overnight fire, despite its inferior construction compared to the WTC.
Just to be clear I was talking about the WTC 7, not the twins so, no planes hitting the building.
Towers..
You are you also implying that there was no mass to be removed, at either of the 2 buildings?
You actually make yourself believe this insanity?
You also make mention of the "The exterior columns falling away"
Well if they did just
fall away, they would not have been found 600ft. away jutting out of other nearby buildings, but you also find it "normal" that this occurred and even post a diagram of the damage circumference.
So which is it? Did the parts of the towers just "fall" 600 ft away?
Seriously I'm having a hard time understanding some of what you are trying to relay here.
Things that just "fall away" would not appear to explosively be ejecting away from the WTC towers, and reach the sited distances you posted.
[ame=http://www.youtube.com/watch?v=aUKLOlIhang]4-Ton Girders: Blowing in the Wind? - YouTube[/ame]
"The floors were being sheared off of the "supporting" mass."
By what mechanism and force?
Are you saying then, that the floors assemblies were detaching from their connections to the columns of the core and perimeter walls, precipitating a chain reaction of floors falling on one another?
In essence the pancake theory?
