Thank you for reply, respectfully, allow me to disagree with a number of your points:
This cannot be used as evidence to support the fact that columns buckled, at best that is a conclusion one can reach after the process of elimination, leaving columns buckling in the realm of possibility, not in the realm of facts. While I agree with the argument that roof falling straight down is indicative of columns failing, it could mean CD as well
You are so far not disagreeing with me, but agreeing completely.
[as well] as a significant failure of the foundation, leaving at least 3 different scenarios that can explain the motion of the roof.
Can you get a bit of detail in here and describe the process you envision? I fail to see how a failure of the foundation would lead to column failure 8 floors above ground, or how such foundation failure would be triggered by the ciscumstances and events that are in evidence.
This scenario requires a leap of logic since there is no casual connection between one column buckling and a complete symmetrical collapse ...
The phrase "complete symmetrical collapse" is bullshit technobabble. There is no documented, objective meaning to the term "symmetrical" as applied to building collapses. If you want to maintain the implied claim that "symmetrical collapse" is actually a thing, please do one of the following:
- Reference a text book or a scientific journal article that defines or discusses the "symmetry" of building collapses
- Describe to me a scientific method to measure objectively the "symmetry" of building collapses - what physical units is "symmetry" expressed in? What threshold values apply to differentiate "asymmetrical", "partially symmetrical" and "completely symmetrical" collapses?
Please think about this earnestly for a few minutes, give it an honest try. I think this excercise has the potential of showing you that "symmetrical collapse" is, indeed, only made-up bullshit technobabble.
Nothing about the WTC7 collapse was, in fact, "symmetrical" in any scientifically meaningful way. The following claims are thus rejected out of hand, for their premise is invalid. I'll address them individually anyway, for they contain more errors of judgement:
... for the following reasons:
1. A column in the east side of the building carries only the weight of the building immediately above itself according to its tributary area; that is to say that the western columns do not share the weight with the eastern side - those are two separate masses connected by horizontal members.
This, if true, is true only for the undamaged, as-designed building. Loads get distributed horizontally once columns start changing capacity and geometry. The part of the collapse sequence that you wish to focus on - the brief moment, a bit over 2 seconds, during which the north face drops a few feet at an average equivalent to free-fall acceleration - comes very late into the collapse sequence, when the core has already completely failed and much of the remaining load already gotten redistributed to the perimeter.
2. The column to beam connections are explicitly designed to fail such that the column is unaffected: if the beam experiences the overload, the connections are designed to fail in such a manner than would not allow the lateral propagation of the collapse.
This is nonsense. First, I do not believe that the beam connections were "designed" in any way, shape or form to manipulate their behaviour in case of a partial collapse - ALL of the building is designed to not collapse in the first place. More importantly, the floor beams (and girders) ALL play a role bracing the columns laterally. You fail a beam, and lateral bracing is effected, thus column capacity diminished.
3. The western penthouse drops just a moment before the whole building while the eastern penthouse drops a few seconds prior. This indicates that should the lateral failure propagation happen we would expect to see the eastern side dropping few seconds before the western side, not simultaneously, since the failure propagation is expected to travel at the same speed in both directions.
You make this up without taking the actual geometry and design of the structure into account. The perimeter columns are heavily bracing each other by means of moment frames. Whether you attribute the fall of the east penthouse to fire or t explosives doesn't change what happened to the eastern part of the north face: It evidently withstood the collapse of the eastern core. Your made-up fantasy cannot change that observed reality. Evidently, lateral bracing to the west core was sufficient for the north face to remain standing for a few seconds. Only when that bracing fell, too, did the north face experience capacity reduction below remaining load.
Absence of evidence is not an evidence of absence. That would not stand to any reasonable scrutiny, furthermore it would work against your argument as well: if absence of audible explosions is evidence of those explosions not being there at all, then lack of visible evidence of columns buckling would also serve as an argument against the columns buckling.
These two are not equivalent throughout.
We do have observations of the sound levels in evidence: All known videos of the WTC7 collapse had sound recording on, specifically those shot from the ground, with hand-held devices, from half a mile away or so. These sound level measurements are not evidence that are absent - this evidence is present! Somethin is absent within that evidence however: Explosion sounds.
In the case of the physical evidence on the ground: You probably cannot point me to any evidence showing the north face perimeter columns, and show me that nowhere along their length, or around the8th floor, there was no sign of buckling. THAT evidence IS indeed absent!
As for what to expect when explosive charges go off, take the Landmark Tower in Ft. Worth as an example. I have two videos here, one from quite near, one from almost half a mile away:
In the second video, the nearby helicopter noise makes the sound recording level go very low, and yet the explosions are clearly heard.
Another reference: Here is a firework that I filmed yesterday. I was probably 400 to 500 feet away:
Each explosive charge you hear weighs mere ounces, some perhaps less than an ounce - low explosives, not high explosives. They were MUCH louder in reality than what this recording shows: When the firework started, I was about 300 feet farther away and inside a house with no window towards the fireworks scene, and yet I heard the first "bang"s clearly.
Explosive charges - high explosives! - capable of cutting the WTC7 steel columns would have needed to be several pounds apiece - extremely much louder than fireworks!
And yet, no sound recorder captured them clearly, no witnesses described them fittingly. There were rescue workers nearby - I read one testimony of a first responder who said that they were astonished to see the tower go down in such relative silence!
So we KNOW what the sounds were near WTC7 when it collapsed - we KNOW there were no explosions consistent in timing, loudness, number and brisance with explosive demolition. It's what the evidence shows that we do have - not absent evidence.
As far as fires goes one can easily envision fireproofed containers or placing the devices within the fireproofed internals of the building.
Please do the envisioning for me!
You are aware that explosives, in order to be effective at cutting steel, must be placed directly onto the steel? If you put any insulation between the explosive and the steel, you decrease effectiveness vastly, which in turn requires that you increase charge size by an enormous factor. Not 5 pounds, say, but 50 or 100 pounds.
Please envision for me how you would go about accesing the perimeter columns ahead of time to place such bulky, insulated devices directly on them?
Yes, you "envision". I call it "fantasize".
Of course you do not have the tiniest bit of evidence for such devices nor their insulation nor the logistics of placing them. Lots of unknowns you introduce with absolutely no evidence whatsoever.
Neither can be used to state with any degree of certainty that there were no explosives, at best it's a circumstantial evidence to make CD hypothesis less likely;
This is FALSE, and the opposite is true: Yes, we can in fact state with some
degree of certainty that there were no explosives. We have positive evidence of there not being the sounds of explosions at the required time with the required loudness. This greatly diminishes the probability of there having been explosive devices that actually exploded and cut columns; a probability that was low to begin with, given the fact that there exists no other evidence for
explosives. So it is with the certainty of overwhelming probability that fires, not explosives, caused the collapse.
such notion is easily countered by the eyewitnesses' reports of explosions
Please cite one (1) eyewitness report of explosions consistent in timing (immediately BEFORE the collapse began), loudness (freaking awesomely LOUD!!!), number (count the columns that are cut in your fantasy) and brisance (high exposives don't rumble - they are very sharp sounds) with explosive demolition of WTC7!
Please just one. Search carefully, please! Present us with the single best, the clearest eyewitness testimony that would support explosive devices at the start of the north face collapse.
I think you may learn from this excercise that NO eyewitness testimony, consistent with explosive CD at the WTC7, actually exists.
- it would also count as only a circumstantial evidence, not enough to prove the explosions did occur, but enough to state that they might have occurred.
Again, if you search for the best such "circumstantial" bit of such evidence, you will come up empty. It doesn't exist.
The columns would only buckle along their unbraced height, otherwise they would provide a significant resistance, therefore making it necessary for the columns to be unbraced for the height of 8 stories to facilitate that period of free fall acceleration due to buckling. Otherwise the building would've been in free fall for a much shorter period of time - only as much as the height of the unbraced buckled column would allow. It is also necessary for the columns to fail within a fraction of the second of each other to explain the motion of the roof that is observed.
You seem to have forgotten already that the entire core was already collapsing BEFORE there was any "free fall" (in scare quotes, because that motion was never ever really "free" fall - more forces than just gravity acted on every part of the wall throughout the collapse). Since the perimeter bracing consisted of floor girders connected to the core, and the core was already dropping, ALL of the bracing had ALREADY been removed. The girders were now a liability - a problem causing
the buckling rather than a measure preventing
I am, but would you not agree that a failure of the northern side of the building would drop that side first?
No, I most certainly disagree: Since the northern side failed last, I clearly would expect to drop last. I am at a complete loss what train of thought led you to this strange idea.
Occam's Razor is not an arbiter of truth, it's tendency of simpler explanations being the correct one.
I agree, but it is a good heuristic guidance to establish a null-hypothesis. The null hypothesis is the one that explains most of the observed data with known facts.
In either case, according to Dr. Sunder of NIST, WTC7 failure was a unique event, first of it's kind; furthermore it is still true that historically no steel frame building experienced a complete collapse due to fires. Those considerations would point Occam's Razor towards the CD hypothesis almost automatically, if we look solely at the WTC7 without going through the whole 9/11. [off topic gish gallop removed by Deirdre]
*Edited for clarity
**Edited for clarity
I am glad Deirdre removed the off topic gish gallop. Just one remark on the bit left standing:
You are - again - wrong, plain and simple. It is NOT true any longer that that historically no steel frame building experienced a complete collapse due to fires. First, many many many steel frame buildings collapse due to fire all the time. Perhaps you meant to include the qualifier "high-rise"? Then this is no longer true, as the collapse of the 15-story Plasco building in Teheran this January has been determined as the result of fires.