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Gage and Szamboti to speak at New Jersey Institute of Technology

Oystein said:
No, not for its stated purpose, which is to present "a simplified approximate analysis of the overall collapse of the towers" as a limiting case. They apply "simplifying assumptions most optimistic in regard to survival", as you know. They explain however:

It boggles the mind why Szamboti is so confident that such a simplified 1D-model would not be flawed for someone analyzing details of the response of the 3D-assembly, such as "jolts" at random points.


Maybe, but that doesn't save your MJ nonsense, because you cannot take Bazant's simplified model, whether his values are flawed or not, to compute the response of details of the 3D-assembly.


This bears quoting in full, so that no one here remains in doubt about the follies of TSz:

Szuladzinski, Szamboti and Johns strangely ignore that the tops tilted before they dropped bodily, and that tilt, being a rotation, has lateral components by definition.
Also, it is weird that Szuladzinski, Szamboti and Johns believe that columns not braced by two guided plates would behave like columns braced by two guided plates. Where did they pull out that idea?!
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Oystein, what is your educational and work background?
 
Oystein said:
No, not for its stated purpose, which is to present "a simplified approximate analysis of the overall collapse of the towers" as a limiting case. They apply "simplifying assumptions most optimistic in regard to survival", as you know. They explain however:

It boggles the mind why Szamboti is so confident that such a simplified 1D-model would not be flawed for someone analyzing details of the response of the 3D-assembly, such as "jolts" at random points.


Maybe, but that doesn't save your MJ nonsense, because you cannot take Bazant's simplified model, whether his values are flawed or not, to compute the response of details of the 3D-assembly.


This bears quoting in full, so that no one here remains in doubt about the follies of TSz:

Szuladzinski, Szamboti and Johns strangely ignore that the tops tilted before they dropped bodily, and that tilt, being a rotation, has lateral components by definition.
Also, it is weird that Szuladzinski, Szamboti and Johns believe that columns not braced by two guided plates would behave like columns braced by two guided plates. Where did they pull out that idea?!
Click to expand...

Column spread as bracing failed was a major factor in column off set.
 
Oystein said:
Address the argument, not the arguer, tyvm. Rule 12 of the MA, in case you forgot.
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I am just wondering why you keep asking the same questions after they or similar questions have been answered several times. This makes it seem like you don't have the background to understand some of the answers, so it may not be possible to address the argument with you in certain cases even though you don't realize it.
 
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Oystein said:
Szuladzinski, Szamboti and Johns strangely ignore that the tops tilted before they dropped bodily, and that tilt, being a rotation, has lateral components by definition.
Click to expand...

I hadn't read that paper (I assumed it was a rehash of Szuladzinski's "discussion" of Bazant's JEM paper, and Tony's name doesn't add any credibility), but I've started to read it now. As I said, I'll leave the structural mechanics issues to the qualified experts, and that discussion should include Bazant's responses to the claims. Most of Bazant's remarks in his "closure" to Szuladzinski indicate that Szuladzinski is out of his depth, but other experts should be able to evaluate the arguments objectively.

I do see where Tony is getting the 6.13 m/s velocity number from:

The averaged acceleration during the early phase of the fall (shown as the slope of the velocity curve in Figure 1) was approximately 5.11 m/s2. The resulting velocity after 1.2 seconds of the fall, which is the approximate time for a fall of one story (3.7 m), is 6.13 m/s (13.71 mi/h).
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But there seems to be another problem with ignoring the tilt and rotation for this calculation: the tilt and rotation were caused by the south side falling faster than the north side, and that was the side that impacted first. Which part of the building was falling at 6.13 m/s, Tony? The NW corner seen in the Sauret video?
 
WilliamSeger said:
I hadn't read that paper (I assumed it was a rehash of Szuladzinski's "discussion" of Bazant's JEM paper, and Tony's name doesn't add any credibility), but I've started to read it now. As I said, I'll leave the structural mechanics issues to the qualified experts, and that discussion should include Bazant's responses to the claims. Most of Bazant's remarks in his "closure" to Szuladzinski indicate that Szuladzinski is out of his depth, but other experts should be able to evaluate the arguments objectively.

I do see where Tony is getting the 6.13 m/s velocity number from:

But there seems to be another problem with ignoring the tilt and rotation for this calculation: the tilt and rotation were caused by the south side falling faster than the north side, and that was the side that impacted first. Which part of the building was falling at 6.13 m/s, Tony? The NW corner seen in the Sauret video?
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The 6.13 m/s velocity after the first story of the fall comes from the north face measurements by David Chandler.

It has been shown that in the North Tower collapse the northeast corner and southwest corner fall within 0.7 seconds of each other so the initiation was quite uniform. There was little to no tilt for the first three stories of the collapse.
 
Tony Szamboti said:
The 6.13 m/s velocity after the first story of the fall comes from the north face measurements by David Chandler.

It has been shown that in the North Tower collapse the northeast corner and southwest corner fall within 0.7 seconds of each other so the initiation was quite uniform. There was little to no tilt for the first three stories of the collapse.
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And you don't see any problem with that logic?
 
Tony Szamboti said:
The 6.13 m/s velocity after the first story of the fall comes from the north face measurements by David Chandler.

It has been shown that in the North Tower collapse the northeast corner and southwest corner fall within 0.7 seconds of each other so the initiation was quite uniform. There was little to no tilt for the first three stories of the collapse.
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At 5.11 m/s2, an object moves 1.25 m in 0.7 s.
The span from NE to SW is 89 meters.
arctan(1.25/89) = 0.8°
If we assume the tilt pivots about the center of mass of the top 12 floors, 6 floors = 22.6 m above the 98th floor which gave way, then the lower column ends would move laterally by
sin(0.8°) * 22.6 m = 0.32 m = 12.5 inches for you USAsians.

Of course I am aware that at that point, not all columns are necessarily severed yet (it's just as the NE corner is about to descend) and so the building can't rotate freely and the pivot wouldn't be where I assume it to be. Merely illustrating that this little tilt, that corresponds to a 0.7 s delay in horizontal collapse progression, makes for very substantial lateral shifts and forces - has to.

To pretend that essentially all columns could descend any substantial distance strictly vertically is foolish.
 
Oystein said:
At 5.11 m/s2, an object moves 1.25 m in 0.7 s.
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And it would be moving at almost 3.6 m/s. If the north face gave way at that point and the top continued to rotate around the CoM, then the south face would have a greater vertical velocity than the CoM, which would have a greater velocity than the north face. Using the 6.13 m/s vertical velocity of the north face (even if accurate) to infer the kinetic energy is completely bogus.
 
Bear in mind that the north o e was also hit nearly dead center and had fewer floors above thee crtitical point if impact. The lower tilt as such doesnt surprise me. As compared to T2 the imposed loads post imact were a lot less eccentric.
 
WilliamSeger said:
And it would be moving at almost 3.6 m/s. If the north face gave way at that point and the top continued to rotate around the CoM, then the south face would have a greater vertical velocity than the CoM, which would have a greater velocity than the north face. Using the 6.13 m/s vertical velocity of the north face (even if accurate) to infer the kinetic energy is completely bogus.
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You are trying to split hairs you can't even see because you can't refute what I am saying. What nonsense and twisted logic. Bazant used free fall velocity in his kinetic energy calculation. Do you think that was right?
 
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Tony Szamboti said:
You are trying to split hairs you can't even see because you can't refute what I am saying. What nonsense and twisted logic. Bazant used free fall velocity in his kinetic energy calculation. Do you think that was right?
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Of course it wasn't.
So what?
He didn't model the real collapse.
He made some assumptions about starting conditions. The implied starting velocity (kinetic energy) he derived from an assumption of 3.7 meters of freefall. Which would be 8.52 m/s2.

His calculation is based on a "first impact" KE equivalent to that v.

There never was a "first impact".

What he shows is that the building is very much doomed once the top moves at 8.52 m/s2 - no matter when that velocity is attained.
It is of course doomed even earlier - we can bitch about the exact number to little avail - in the best case for survival: full axial impact, that never was.

In real life, there never was freefall, but there also was never the best case condition.

If/since there wasn't freefall, the structure was destroyed along the way to the tune of m*(g-a)*h, which further removes it from the best case scenario.
 
WilliamSeger said:
Oystein said:
At 5.11 m/s2, an object moves 1.25 m in 0.7 s.
Click to expand...
And it would be moving at almost 3.6 m/s. If the north face gave way at that point and the top continued to rotate around the CoM, then the south face would have a greater vertical velocity than the CoM, which would have a greater velocity than the north face. Using the 6.13 m/s vertical velocity of the north face (even if accurate) to infer the kinetic energy is completely bogus.
Click to expand...

Actually, come to think of it, if the south face was falling when the north face wasn't, the acceleration value (whatever it really was) should be applied to the CoM, and the drop and velocity at the south face would be twice those at the CoM. (The 5.11 m/s2 is bogus since it was derived only from the rotating north face, so these calcs using that value aren't really accurate, but surely Tony can see the point?)
 
WilliamSeger said:
Actually, come to think of it, if the south face was falling when the north face wasn't, the acceleration value (whatever it really was) should be applied to the CoM, and the drop and velocity at the south face would be twice those at the CoM. (The 5.11 m/s2 is bogus since it was derived only from the rotating north face, so these calcs using that value aren't really accurate, but surely Tony can see the point?)
Click to expand...

That's assuming a totally rigid "block", so don't take the value as anything resembling reality; it's merely a tendency.
 
Oystein said:
Of course it wasn't.
So what?
He didn't model the real collapse.
He made some assumptions about starting conditions. The implied starting velocity (kinetic energy) he derived from an assumption of 3.7 meters of freefall. Which would be 8.52 m/s2.

His calculation is based on a "first impact" KE equivalent to that v.

There never was a "first impact".

What he shows is that the building is very much doomed once the top moves at 8.52 m/s2 - no matter when that velocity is attained.
It is of course doomed even earlier - we can bitch about the exact number to little avail - in the best case for survival: full axial impact, that never was.

In real life, there never was freefall, but there also was never the best case condition.

If/since there wasn't freefall, the structure was destroyed along the way to the tune of m*(g-a)*h, which further removes it from the best case scenario.
Click to expand...

It would be informative if this Bazant "jolt" business was redone.

1-use best info on actual column size,etc

2- use best info on "upper part" weight

3- assume that as in Bazant's fantasy case, the columns line up.


a- at what velocity would the impacts result in failure

b- how far would the drop need to be at 1g acceleration to get to this velocity

c- at .9g

d- .8g

e - etc...
 
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