I do not "carp," and you can stop the personal attacks. You don't know me so you have no basis whatsoever for feigning intellectual superiority over me.
I do concede that you made valid points with respect to the combustion temperature of kerosene and the melting points of steel and aluminum. However, your argument that the upper floors would "not have time to lean" is flawed. The Initial impact damage to columns on that floor is unknown, but it is presumably that the force could have dented them a bit. I am not making that argument. Assuming that your assertions about the columns reaching their yield limit due to the heat of the fire, that could only have occured in the columns which were directly or very near the fire itself. Those columns would have bent first before failing completely, and the asymmetric forces one adjacent columns would occur as dominoes falling, in essence. This would absolutely NOT have resulted in a perfect demolition footprint a one 110-story tower -- let alone TWO, also in it's perfect footprint with no asymmetric collapse.
I have seen videos of the controlled demolition explosions going off sequentially toward the ground.
Save your snide remarks for someone who will accept it from you. I will not stop yo your level in that regard. After all, what is the point of creating animosity toward perfect strangers, when we are only addressing our divergent perceptions of what happened? The answer is, there is NO point. Direct your bitterness and feigned intellectual superiority elsewhere.
Now we begin to have a technical discussion, which is fine by me. We're talking about the columns in the 6 floors that were involved in the collision. I have made no assumptions about any damage from the collision itself, only that the fire occupied the central area of the floors. I have no idea what the structural factor of safety was, but I would expect it to be at least 2. Structural steel loses 70% of its strength at a temperature of 600 deg C (only 90% of the temperature of molten aluminum; wherever there was molten aluminum, there would have been critically weakened steel). The question becomes how much of the floor area was at this temperature or above, given that the flame temperature was over 2000 deg C. My point is that, through the loss of structural strength from high temperature, it is plausible to think that a very large fraction of the floor was incapable of supporting any structural load, and that this load was being carried by outer columns.
Columns would bend only if the applied stress was above the yield strength BUT below the ultimate strength. If the stress was above the ultimate strength, the beam would simply shear. Many of the central columns could have done this. When the conditions were such that the upper-story load equaled the effective limit load for the remaining columns. the catastrophic chain reaction could take place. Because the load conditions on each individual column would be different (different exact temperature, different exact loading) the failures would be stochastic---and would all happen in a matter of milliseconds, as I mentioned previously. In the course of those tens of milliseconds, the specific supports beneath the upper floors would be vanishing randomly at the rate of maybe 1000/second (or faster). There would be no consistent tipping moment. And there would be no tipping in that time interval; the rotational inertia of the upper floors would prevent it. If you doubt it, figure out the tipping moment from a support location that would be in place for only 5 milliseconds, estimate the rotational inertia of the upper floors, and figure out what the torque would be and how much tilt would accumulate in those 5 milliseconds. (Even so, it seems there was some small tilt that accumulated during the full collapse.)
Your logic is inside-out. If this can happen to one tower, it can definitely happen to the other tower. It does not depend on any unique configurations of columns, because ALL configurations go away in tens of milliseconds.
What you may think to be demolition explosions were probably catastrophic shear failures of the freshly loaded columns beneath the collapsing mass above. Do you think a shear failure is not a violent event?
Snide remarks? Did I call you a glowie or did you call me a glowie?
I would only say I have analysis and you have opinion.
But let me apologize for the "glowie" question. It is really hard to sort the thread when it gets into these extensions, and our discussion was remarkably similar to the discussion I was having with someone who did call me a "glowie." I didn't appreciate that.
I do not "carp," and you can stop the personal attacks. You don't know me so you have no basis whatsoever for feigning intellectual superiority over me.
I do concede that you made valid points with respect to the combustion temperature of kerosene and the melting points of steel and aluminum. However, your argument that the upper floors would "not have time to lean" is flawed. The Initial impact damage to columns on that floor is unknown, but it is presumably that the force could have dented them a bit. I am not making that argument. Assuming that your assertions about the columns reaching their yield limit due to the heat of the fire, that could only have occured in the columns which were directly or very near the fire itself. Those columns would have bent first before failing completely, and the asymmetric forces one adjacent columns would occur as dominoes falling, in essence. This would absolutely NOT have resulted in a perfect demolition footprint a one 110-story tower -- let alone TWO, also in it's perfect footprint with no asymmetric collapse.
I have seen videos of the controlled demolition explosions going off sequentially toward the ground.
Save your snide remarks for someone who will accept it from you. I will not stop yo your level in that regard. After all, what is the point of creating animosity toward perfect strangers, when we are only addressing our divergent perceptions of what happened? The answer is, there is NO point. Direct your bitterness and feigned intellectual superiority elsewhere.
Now we begin to have a technical discussion, which is fine by me. We're talking about the columns in the 6 floors that were involved in the collision. I have made no assumptions about any damage from the collision itself, only that the fire occupied the central area of the floors. I have no idea what the structural factor of safety was, but I would expect it to be at least 2. Structural steel loses 70% of its strength at a temperature of 600 deg C (only 90% of the temperature of molten aluminum; wherever there was molten aluminum, there would have been critically weakened steel). The question becomes how much of the floor area was at this temperature or above, given that the flame temperature was over 2000 deg C. My point is that, through the loss of structural strength from high temperature, it is plausible to think that a very large fraction of the floor was incapable of supporting any structural load, and that this load was being carried by outer columns.
Columns would bend only if the applied stress was above the yield strength BUT below the ultimate strength. If the stress was above the ultimate strength, the beam would simply shear. Many of the central columns could have done this. When the conditions were such that the upper-story load equaled the effective limit load for the remaining columns. the catastrophic chain reaction could take place. Because the load conditions on each individual column would be different (different exact temperature, different exact loading) the failures would be stochastic---and would all happen in a matter of milliseconds, as I mentioned previously. In the course of those tens of milliseconds, the specific supports beneath the upper floors would be vanishing randomly at the rate of maybe 1000/second (or faster). There would be no consistent tipping moment. And there would be no tipping in that time interval; the rotational inertia of the upper floors would prevent it. If you doubt it, figure out the tipping moment from a support location that would be in place for only 5 milliseconds, estimate the rotational inertia of the upper floors, and figure out what the torque would be and how much tilt would accumulate in those 5 milliseconds. (Even so, it seems there was some small tilt that accumulated during the full collapse.)
Your logic is inside-out. If this can happen to one tower, it can definitely happen to the other tower. It does not depend on any unique configurations of columns, because ALL configurations go away in tens of milliseconds.
What you may think to be demolition explosions were probably catastrophic shear failures of the freshly loaded columns beneath the collapsing mass above. Do you think a shear failure is not a violent event?
Snide remarks? Did I call you a glowie or did you call me a glowie?
A compelling argument, fren. I will definitely take this under advisement.
I don't care to debate this. You have your opinion and I have mine.
Moving on . . .
I would only say I have analysis and you have opinion.
But let me apologize for the "glowie" question. It is really hard to sort the thread when it gets into these extensions, and our discussion was remarkably similar to the discussion I was having with someone who did call me a "glowie." I didn't appreciate that.