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Politics : Bush-The Mastermind behind 9/11? -- Ignore unavailable to you. Want to Upgrade?

To: Don Earl who wrote (5717)	3/19/2004 1:18:31 PM
From: zonder	Read Replies (1) \| Respond to of 20039

Nonsense Only if you have never studied construction. I have. The Empire State building is entirely reinforced concrete. I think you are wrong on the "entirely" part. If I recall correctly, its SLABS (i.e. floors) are reinforced concrete, while the FRAME is steel. The presence of reinforced concrete might actually be how the building survived the crash of a B-25 bomber in 1945. Again, I am writing this from memory, but from what I recall, the only reason why there was more concrete used in the construction of Empire State Building was to save steel which was in shortage as it was needed for war production - the steel they saved was enough to build a battleship. The use of concrete ramps rather than elevators reduced the need for steel in the structure. In other words, you might want to take back that "nonsense" remark :-) You appear to be making this stuff up as you go along No. Rather, I am recalling one full semester course I took on "Structure" and another full semester course I took on "Strength" (of materials). There has never been a case of a steel building collapsing as a result of fire Possibly. Frankly, the issue is not worth the half hour I would have to spend on Google checking on that statement. The fact remains that steel structures are weak against fire, which reduces their load bearing strength. It is taught in schools that way, and there is a reason for that. Any civic engineed would be able to tell you that.

To: Don Earl who wrote (5717)	3/19/2004 3:09:52 PM
From: Raymond Duray	Read Replies (1) \| Respond to of 20039

OT -- Empire State Building Don, Re: . The Empire State building is entirely reinforced concrete. I don't think so. The Empire State was construced by means of a steel frame which was heavily fireproofed with concrete. But it is certainly not a "reinforced concrete" structure.

To: Don Earl who wrote (5717)	3/19/2004 3:57:32 PM
From: X Y Zebra	Read Replies (2) \| Respond to of 20039

Nonsense. The Empire State building is entirely reinforced concrete. The Empire State building is built on the "cake principle"; this being that the lower floor being larger than the upper one and so on.... roughly, like a "pyramid". The Twin towers were built on the flag-pole principle, meaning that depending on the height of the building, a specific number of feet are "built down" into the ground. Besides.... Concrete at certain temperature will also be destroyed; it will "explode"; steel will melt and bend. Concrete is tested on a building site by putting pressure on it to see if its quality will withstand whatever is it that it will be used on. This test piece will withstand so much of it and then when it "gives", it "explodes" and pulverizes it... fire, at a given temperature will destroy concrete as well There has never been a case of a steel building collapsing as a result of fire, and the WTC buildings were specifically engineered to withstand the impact of a 707. Well... it obviously did not succeed. Not so much for the impact, but... guess why...? --> Fire. It is my understanding that the NYC Chief fire marshal and his lieutenants were monitoring the temperature of the "core" of the towers and at a given point in time the math told them the buildings would collapse as they did... they probably did not think it would happen. It is also my understanding that the reason the towers collapsed was a combination of factors that leads me to believe that the terrorists knew exactly what they were doing; these factors being: 1. The failure of an important component of the steel structure, this being the "core” of the building, i.e. the channel created to bring all services/utilities, such as cables, pipes etc. to the offices. At the same time, this core aided the fire by allowing oxygen to be brought up to the center of the fire, and then create a chimney effect on the way up, past that point; this too aiding the intensity of the fire and the failure of the sprinkler system to fight it. This core failed given the temperature and length of the fire created by the jet fuel. The core is like a doughnut built up vertically as high as the building is. Once that core is weakened by fire... good luck... obviously, the jet fuel in this instance succeeded in destroying it. 2. the fuel used and amount of same... jet fuel is a very "explosive" fuel more so than regular gasoline, plus the amount of it... all flights crashed into these buildings were in the first leg of long trips, filled with jet fuel. This had the effect of burning quickly, at very high temperature, and designed to last for a long time, (given the amount of it). 3. The "height" at which the planes hit was the perfect one as it allow for sufficient supply of oxygen through the core to the burning fire... once the core collapsed, then the weight of floors above added to the destruction... 4. The fire-sprinkler system failed to stop the fire because it simply was overwhelmed by both the intensity of the fire and the amount of fuel used... it simply failed to "douse" the initial fire and from then on the system was destroyed, rendering it non-functioning. You're also confusing fire rated barriers with total destruction. Generally, residential buildings require 1 hour fire rated barriers between areas such as attached garages and ceilings. For commercial buildings, the requirement is generally 2 hour rated barriers. Re: commercial structures, in some cases, the existence of a fire suppression system (fire sprinkler system), voids the need for fire rated walls...) however, use of specific equipment may change that. Fire insurance companies "rate" buildings in order to establish premiums... they actualy do not care much if the building is made out of steel or not, there are other more importat considerations that affect the premium, such as "use of the building" equipment employed and.... most importantly.... Fire Supression Systems (sprinkled systems)... this translates into fire will eat up ANY type of structure, steel included... and while the Twin Towers nobody imagined that they would collapse the way they did.... it was fire that killed them... steel or not.