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Originally posted by Slap Nuts
Thanks, but your core assumption that if ONE FLOOR were to collapse that all would collapse, straight down is FLAWED. It is NOT only on floor offering RESISTANE... It is 1000 FEET of BOX STEEL COLUMS anchored in BEDROCK.
The math you offer is moot as you assume that if one floor is removed that there will be some sort of "terminal energy" that the structure could not arrest. This assumption is not supported by the design of the building.
Originally posted by bsbray11
Any floor could handle more than twice its design loads and yet buckling a handful of columns on a floor somehow does more damage to its structure than if over half of them 100% failed.
Originally posted by pavil
So what exactly was the design load of a WTC floor? I asked this earlier and would like to know.
The load rating for columns in the perimeter area was 50 psf. The load rating for the core area was up to 100 psf. This comes out to be an estimated 75 psf average for an office floor. The load ratings for floors 110-94 average out to be about 82 psf (3.9 kPa) per floor. On average, a floor's design live load was 1,488 tons. The estimated total weight of a floor, dead load plus live load, is 3,306 tons. Add the factor of safety and the building structure could handle multiple times this load. It is estimated that the average factor of safety for a floor was 3.35. This means a floor could handle a total of 11,075 tons before failing. To visualize, imagine 5,500 2-ton cars stacked in a square about 1/3 of a city block.
I still contend that once the floors started collapsing due to the combo of impact, explosion and fires, there was too much load on each successive floor to handle and they each failed in turn.
Originally posted by pavil
BB,
In your opinion how many additional floors of weight could a single floor of the WTC support till it failed? Assume completely intact floors for th sake of this argument ie no loss of weight due to falling off edge, pulverization ect.
For example, would 3 total additional floors of weight on an existing structurally intact floor be enough for it to fail? Using the figures you gave above it would be 2.35 additional complete floors. If not what is your number.
[edit on 13-7-2006 by pavil]
Originally posted by Slap Nuts
"A Floor" is NOT supporting the weight of the floor above it. Very large and Very strong steel box colums were supporting the weight alnog with an outter lattice design supporting the rest.. these were anchored into bedrock. It is not a "toothpick" design or a house of cards.
As weight is being REMOVED from the box colums and from the lattice how are they being weakened?
Originally posted by Slap Nuts
"A Floor" is NOT supporting the weight of the floor above it.
Originally posted by pavil
In your opinion how many additional floors of weight could a single floor of the WTC support till it failed? Assume completely intact floors for th sake of this argument ie no loss of weight due to falling off edge, pulverization ect.
For example, would 3 total additional floors of weight on an existing structurally intact floor be enough for it to fail? Using the figures you gave above it would be 2.35 additional complete floors. If not what is your number.
Originally posted by bsbray11
If the structure held up the way you're thinking it did, the bottom floors would not have been able to hold the 100's of floors above them, would they? If it was a matter of two or three additional floors to get the towers to collapse, the towers could never have been built past floor 4 or 5.
Think about it -- for the floors that were designed to carry the weight of all the floors above, you'd be stacking twice the floors above them to reach that 2.35 x more weight or whatever. Make sense?
Originally posted by pavil
Not really, Each floor is designed to withstand it's own load with a hefty safety margin plus the overall support structure,
Why is it so suprising to you that the WTC's once compromised by a crash, explosion and fire, started a collapse by the impact zone and that an intact floor below, not designed to withstand that much stress, failed and fell down, adding even more weight onto the next floor and so on.
Originally posted by bsbray11
Again, if you took one of the middle floors, say floor 60, and stacked 50 more floors on top of it (the number of floors that DID rest on top of it), would it collapse?
It certainly would going by your logic, that a floor could only withstand its own weight plus the weight of a few more floors. Yet the Towers stood for decades. How, pavil?
1) Most of the debris fell outside of the buildings, off to the sides, and landed outside of the footprints. Therefore most could not also have fallen straight down onto the floors below, so not even a majority could have done what you're suggesting.
Originally posted by pavil
To use your analogy, would a floor, which is designed to certain tolerances be able to support those additional floors, if those additional floors had no supports of their own?
40% of WTC1 above impact 13 floors = 5.2 floors falling in footprint.
40% of WTC2 above impact 30 floors = 12 floors falling in footprint.
To me that is enough to start the events in motion. To you, it is not.
Obviously we disagree. Such is the debate.
Can you honestly tell me that if a floor went from a normal load and could withstand up to 3 times that normal load as a safety factor, that it could support over 6 times the normal load and not fail?
Originally posted by pavil
So what exactly was the design load of a WTC floor? I asked this earlier and would like to know.