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from:www.nist.gov...
12. Was there enough gravitational energy present in the WTC towers to cause the collapse of the intact floors below the impact floors? Why weren't the collapses of WTC 1 and WTC 2 arrested by the intact structure below the floors where columns first began to buckle?
Yes, there was more than enough gravitational load to cause the collapse of the floors below the level of collapse initiation in both WTC towers. The vertical capacity of the connections supporting an intact floor below the level of collapse was adequate to carry the load of 11 additional floors if the load was applied gradually and 6 additional floors if the load was applied suddenly (as was the case). Since the number of floors above the approximate floor of collapse initiation exceeded six in each WTC tower (12 floors in WTC 1 and 29 floors in WTC 2), the floors below the level of collapse initiation were unable to resist the suddenly applied gravitational load from the upper floors of the buildings.
Consider a typical floor immediately below the level of collapse initiation and conservatively assume that the floor is still supported on all columns (i.e., the columns below the intact floor did not buckle or peel off due to the failure of the columns above). Consider further the truss seat connections between the primary floor trusses and the exterior wall columns or core columns. The individual connection capacities ranged from 94,000 pounds to 395,000 pounds, with a total vertical load capacity for the connections on a typical floor of 29,000,000 pounds (see Section 5.2.4 of NIST NCSTAR 1-6C). The total floor area outside the core was approximately 31,000 square feet, and the average load on a floor under service conditions on Sept. 11, 2001, was 80 pounds per square foot. Thus, the total vertical load on a floor outside the core can be estimated by multiplying the floor area (31,000 square feet) by the gravitational load (80 pounds per square foot), which yields 2,500,000 pounds (this is a conservative load estimate since it ignores the weight contribution of the heavier mechanical floors at the top of each WTC tower). By dividing the total vertical connection capacity (29,000,000 pounds) of a floor by the total vertical load applied to the connections (2,500,000 pounds), the number of floors that can be supported by an intact floor is calculated to be a total of 12 floors or 11 additional floors.
This simplified and conservative analysis indicates that the floor connections could have carried only a maximum of about 11 additional floors if the load from these floors were applied statically. Even this number is (conservatively) high, since the load from above the collapsing floor is being applied suddenly. Since the dynamic amplification factor for a suddenly applied load is 2, an intact floor below the level of collapse initiation could not have supported more than six floors. Since the number of floors above the level where the collapse initiated exceeded six for both towers (12 for WTC 1 and 29 for WTC 2), neither tower could have arrested the progression of collapse once collapse initiated. In reality, the highest intact floor was about three (WTC 2) to six (WTC 1) floors below the level of collapse initiation. Thus, more than the 12 to 29 floors reported above actually loaded the intact floor suddenly.
13. Were the basic principles of conservation of momentum and energy satisfied in NIST's analyses of the structural response of the towers to the aircraft impact and the fires?
Yes. The basic principles of conservation of momentum and conservation of energy were satisfied in these analyses.
In the case of the aircraft impact analyses, which involved a moving aircraft (velocity) and an initially stationary building, the analysis did, indeed, account for conservation of momentum and energy (kinetic energy, strain energy).
After each tower had finished oscillating from the aircraft impact, the subsequent degradation of the structure involved only minute (essentially zero) velocities. Thus, a static analysis of the structural response and collapse initiation was appropriate. Since the velocities were zero and since momentum is equal to mass times velocity, the momentum terms also equaled zero and therefore dropped out of the governing equations. The analyses accounted for conservation of energy.
Here is a MIT paper too.
Paper Title: Why Did the World Trade Center Collapse?—Simple Analysis - MIT Mathematics, At www-math.mit.edu › WTC › WTC-asce
so you're claiming that no steel columns were pulverized in WTC 1 & 2?
originally posted by: cavtrooper7
Bush family are reptiles.
originally posted by: neutronflux
a reply to: facedye
I am saying rod mills pulverizes rock and the steel rod charge needs replace do to steel rods breaking and wearing down with time. That is with only ten tons of rods only effectively falling three feet and the mill rotating at 2 RPM. So, it's not a contradiction.
But pulverized steel dose not even meet the logic rule.
Overhead pictures of the WTC pile clearly shows large steel columns.
Work crews spent months cutting up WTC columns for removal.
Whole lay down yards of WTC columns were established.
originally posted by: neutronflux
a reply to: facedye
I am saying rod mills pulverizes rock and the steel rod charge needs replace do to steel rods breaking and wearing down with time. That is with only ten tons of rods only effectively falling three feet and the mill rotating at 2 RPM. So, it's not a contradiction.
But pulverized steel dose not even meet the logic rule.
Overhead pictures of the WTC pile clearly shows large steel columns.
Work crews spent months cutting up WTC columns for removal.
Whole lay down yards of WTC columns were established.
From: 911encyclopedia.com...
The total weight of structural steel in the each WTC tower is approximently 100,000 short tons. (MassAndPeWtc.pdf)
The initial debris estimate included 125,000 tons of glass, 250,000 of tons of steel, 450,000 cubic yards of concrete, 12,000 miles of electrical cable, and 198 miles of ductwork. Trade Center Forensic Recovery.pdf disaster.pandj.com
From: 911encyclopedia.com...
The last debris was processed on July 26, 2002, day 321 of the project. At the close of the Staten Island Landfill mission:
• 1,462,000 tons of debris had been received and processed
• 35,000 tons of steel had been removed (165,000 tons were removed directly at Ground Zero)