If it doesn't agree with experiment, it's wrong. Part II

[ozeco41]

femr2 once asked what was the minimum height necessary to cause collapse according to Bazant's equations. Myriad calculated it. The result was in the order of 1 mm. So, you're probably right if even because of the looseness of the bolts.

It seems to me that, for a structure with an overall factor of safety of exactly two, then the minimum height is infinitesimally greater than zero.

Dave

The engineering logic is as trivial as that. Provided it is "Suddenly applied load" then FoS of 2 is the threshold point - and any drop increasing the impact - even as little as 1mm - theoretically would cause collapse by the Bazant Limit mechanism.

But that lot is theoretical and pragmatic actual is rarely that predictable.

And we need to take care using global FOS for all the usual reasons - like it is nonsense in a progressive cascade failure. But acceptable in the theoretical but could never happen in real life scenario of the Bazant abstract model which had concurrent distributed axial contacts of columns falling through a gap. Bazant originally proposed one storey but he and later researchers reduced that and the 1mm gap is theoretically all that is needed to slightly raise the impact forces above the 2 times for "suddenly applied load".

And it all begs the question of how you could ever get to that point in a real situations. Whether Bazant's original 1 storey or his and other later lesser drops.

There is another outstanding issue - unresolved AFAIK - the suggestion that Bazant/Zhou got the sums wrong as proposed by Sz, Sz & Johns. It has not been rebutted or even seriously challenged AFAIK. However Dave you said Global FOS 2 - If that is the actual FOS of 2 - based on real weight not someone's calculation - then it glosses over - subsumes - whether the sums were right or not.

 

[Dave Rogers]

There is another outstanding issue - unresolved AFAIK - the suggestion that Bazant/Zhou got the sums wrong as proposed by Sz, Sz & Johns. It has not been rebutted or even seriously challenged AFAIK. However Dave you said Global FOS 2 - If that is the actual FOS of 2 - based on real weight not someone's calculation - then it glosses over - subsumes - whether the sums were right or not.

Agreed, and one of the points Tony Sz loves to stress is that his calculations of FOS differ from Bazant/Zhou. At best he can even argue that the BZ collapse mechanism would not inevitably result in global collapse, which from his point of view - though not that of anyone who understands the real, as opposed to the idealized, mechanism - seems indistinguishable from proving that global collapse was impossible. The resolution of this paradox by invocation of a different, less energetic collapse mechanism is, I'm sure, rejected as ideologically less satisfying than silent and invisible explosives.

Dave

 

[jaydeehess]

And even that assertion by NIST is very conservative:
Suddenly applied load? AND "2"?

Yes - 2 is correct for "suddenly applied load" BUT I'll bet the non engineers/physicists don't know what "suddenly applied load" means.

And why reality could have been much more than 2.

In first year physics lab we did an experiment on various wires to determine the Young's modulus of the material the wire was made of(Steel, aluminum, copper, iirc). Instructions were very explicit that when loading the wire, the load MUST be applied very slowly and carefully. The wire is stretching, applying quickly will mean that the initial stretch is due to a dynamic load which will impart momentum to the load which in turn must now be transfered to the wire which represents an additional force on the wire during that momentum transfer.

IOW, the structure must absorb the change in momentum over time and dp/dt=Force (added mass causes materials to flex therefore you have more mass that is moving=momentum)

do I's be close?

 

[ozeco41]

Agreed, and one of the points Tony Sz loves to stress is that his calculations of FOS differ from Bazant/Zhou. At best he can even argue that the BZ collapse mechanism would not inevitably result in global collapse, which from his point of view - though not that of anyone who understands the real, as opposed to the idealized, mechanism - seems indistinguishable from proving that global collapse was impossible. The resolution of this paradox by invocation of a different, less energetic collapse mechanism is, I'm sure, rejected as ideologically less satisfying than silent and invisible explosives.

Dave

I just corrected one of Tony's persistent errors on another forum where he was trying to deceive the locals.

He uses global FoS of a set of columns when the situation is dynamic. Specifically the cascade failure of Twin Towers "initiation" stage. It is bleeding nonsense.

The full set of remaining columns at any stage may have FoS in excess of 1 - so Tony says "it wont fail".

As you I and most physics competent persons know the true situation for a dynamic cascading situation is that the NEXT column to fail is the one that matters and fwatits wurth the FoS of that column will be <1 Even if the full set of columns has FoS well in excess of 1. On forums with people having varying levels of comprehension of the physics I always suggest avoid using FoS concepts,

Its closely related to the error we often saw in earlier times of people presuming that if you remove 25% of columns the remaining ones will see a uniform load increase of 33%. Hogwash - it depends on the location of the columns and loads. And in any practical "cut out a proportion of columns" situation the load increase on remaining columns will always have some columns worse than proportional re-allocation.

 

[ozeco41]

In first year physics lab we did an experiment on various wires to determine the Young's modulus of the material the wire was made of(Steel, aluminum, copper, iirc). Instructions were very explicit that when loading the wire, the load MUST be applied very slowly and carefully. The wire is stretching, applying quickly will mean that the initial stretch is due to a dynamic load which will impart momentum to the load which in turn must now be transfered to the wire which represents an additional force on the wire during that momentum transfer.

IOW, the structure must absorb the change in momentum over time and dp/dt=Force (added mass causes materials to flex therefore you have more mass that is moving=momentum)

do I's be close?

Yes. Close. "suddenly applied" is one specific type of impact loading. Already in contact. No momentum of impact - in WTC scenario it would be no drop to contact. As soon as you have any drop == velocity of impact the effective load becomes higher than 2 times weight.

 

[jaydeehess]

I just corrected one of Tony's persistent errors on another forum where he was trying to deceive the locals.

He uses global FoS of a set of columns when the situation is dynamic. Specifically the cascade failure of Twin Towers "initiation" stage. It is bleeding nonsense.

The full set of remaining columns at any stage may have FoS in excess of 1 - so Tony says "it wont fail".

As you I and most other know the true situation for a dynamic cascading situation is that the NEXT column to fail is the one that matters and fwatits wurth the FoS of that column will be <1 Even if the full set of columns has FoS well in excess of 1. On forms with people having varying levels of comprehension of the physics I always suggest avoid using FoS concepts

Why is that so difficult to envision? A collection of columns. Then a collection of columns which sees a non-uniform redistribution of load from suddenly removed, asymmetric subset of those columns. Columns then are heated, reducing individual column strengths. Column(s) under the most load and most strength loss fails. New, again non-uniform load redistribution. That redistribution fails another column,,redistribution, column(s) fail,, cascade failure!

Why, indeed how, can TSz expect a uniform redistribution of loads? Why would he expect that global FoS is uniform across the entire structure, to be uniformly applied when an asymmetric removal of some columns occurs?
(rhetorical questions,,, I know you cannot answer why he believes this)


Three legged stool analogy applies as well. One leg is removed. The two remaining legs may well be able to support a load ten times what is being applied but only two legs cannot actually keep the structure upright.

 

[ozeco41]

Why, indeed how, can TSz expect a uniform redistribution of loads? Why would he expect that global FoS is uniform across the entire structure, to be uniformly applied when an asymmetric removal of some columns occurs?
(rhetorical questions,,, I know you cannot answer why he believes this)


Three legged stool analogy applies as well. One leg is removed. The two remaining legs may well be able to support a load ten times what is being applied but only two legs cannot actually keep the structure upright.

It is hard to accept that he believes. I'm no expert on the psychology of obsessive belief.

BUT when a person like Tony or R Gage has multiple times made the same erroneous assertion and nearly as many times been advised of the error AND the correct reasoning - I don't comprehend how obsession can cause such denial resulting in "belief" not being doubted.

I'm very careful using the word "liar" or derivatives of "lie" but repeating untruths after a competent professional tells you otherwise must qualify.

And for someone to be using applied physics principles in their work whilst in their leisure activities they deny those principles must IMO cause some horrible mental conflicts >> stress.

 

[Oystein]

To avoid though problems with the huge crane and how the cable behaves, how about you imagine you had a switch with which you can switch on and of earth's gravity in zero time.
Imagine you switch gravity off - and suppose that doesn't destroy the column joints already (as elastic strain energy is released).
Wait till the tower comes to rest.
Then switch gravity back on:

You engineering and physics types will understand that FoS = 2 is not sufficient to avert total collapse (for some vertical member will have local FoS < 2 and fail, reducing overall FoS to < 2; and so on).
The non-engineering and non-physics types may more likely read this with incredulity.

 

[Dave Rogers]

To avoid though problems with the huge crane and how the cable behaves, how about you imagine you had a switch with which you can switch on and of earth's gravity in zero time.

Yes, that would work equally well, though I'm not sure being able to switch off one of the four fundamental forces of the Universe is necessarily a simpler proposal than building a big crane.

Dave

 

[jaydeehess]

Your posts haven't been deleted. Another lie by you.

They reside in a different section of this forum and you've received PM's notifying you of such.

I don't know why CTs always use hyperbole to refer to posts moved to AAH as "deleted".

On many CT 911 sites, posts do completely disappear, sometimes without mod comment. On PfffT ALL (each and every) posts by a non-believer are moved to a special subforum.

 

[jaydeehess]

To avoid though problems with the huge crane and how the cable behaves, how about you imagine you had a switch with which you can switch on and of earth's gravity in zero time.
Imagine you switch gravity off - and suppose that doesn't destroy the column joints already (as elastic strain energy is released).
Wait till the tower comes to rest.
Then switch gravity back on:

You engineering and physics types will understand that FoS = 2 is not sufficient to avert total collapse (for some vertical member will have local FoS < 2 and fail, reducing overall FoS to < 2; and so on).
The non-engineering and non-physics types may more likely read this with incredulity.

Now try it in such a way as gravity does not come on uniformly across the entire structure at the same rate. (ie, around the perimeter it ramps up to full in xmilliseconds while in the core it ramps up to full in x+y milliseconds, north side gravity starts to ramp up at time=0, south side it starts at time=z) After all the tower columns did not have extra load applied uniformly.

 

[tfk]

In first year physics lab we did an experiment on various wires to determine the Young's modulus of the material the wire was made of(Steel, aluminum, copper, iirc). Instructions were very explicit that when loading the wire, the load MUST be applied very slowly and carefully. The wire is stretching, applying quickly will mean that the initial stretch is due to a dynamic load which will impart momentum to the load which in turn must now be transfered to the wire which represents an additional force on the wire during that momentum transfer.

IOW, the structure must absorb the change in momentum over time and dp/dt=Force (added mass causes materials to flex therefore you have more mass that is moving=momentum)

do I's be close?

You cannot drop a weight onto the wire. That obviously produces dynamic load that will totally screw your data, even if it doesn't snap the wire. And you will get longitudinal oscillations (that'll couple to lateral oscillation) if you do this. The wire's a very stiff slinky.

But let's assume that you use an Instron, or some such pulling machine, to pull the wire to failure.

Over the range of speeds that the machine is capable, you won't see any difference in yield strength, ultimate strength or Young's modulus. There are some issues with the performance of the machine. You may well have some problems with wire slipping (sometime stick-slipping) in the specialized wire grippers, for example.

In the old days, they used "load cells" & LVDTs as the force & displacement sensors, respectively. The load cell was a stiff, heavy cantilever that had a calibrated strain (deflection) vs. force curve. A strain gauge translated strain into force.

The LVDT is a terrific device: one of the very, very few transducers that has literally infinite resolution.

All of those components are heavy & therefore generate significant inertial forces when you accelerate them. But that's a measurement issue, not a change in the performance of the wire itself.

I'm not sure what sensors they use these days.

I remember seeing that you can consider the performance of most steels to be equivalent to its "low strain rate" numbers up to around 2000 ft/sec strain (~12% of sonic velocity in the steel, IIRC).

It's fairly typical, btw, for small diameter wires to show somewhat increased yield strength & dramatically increased ultimate strength over bulk material. It has to do with the low probability of a grain boundary forming within the diameter of the wire.

One thing that does change dramatically with VERY high strain rates is the elongation before failure. A typical steel that could withstand 8% strain will be able to survive nearly twice that if the strain rate is high enough.

This is the basis of explosive forming & explosive assembly.

 

[Cosmic Yak]

Do you speak Arabic? If not, how can you be certain that the translation is accurate?

His "confession" does not disprove CD.

It also has nothing to do with Cole's experiment.

I haven't yet had time, but I will run the video past some of my Arabic-speaking colleagues to check.
However, this video has been in the public domain for some years now, without (as far as I am aware) any disagreement with the accuracy of the translation. With all the detailed and diligent research being done by truthers ( ), surely at least one of them would have published a more accurate translation, if one were needed. That fact that this has not been done adds yet more credibility to its veracity.
Finally, you have (I assume unwittingly) undermined your own argument. You argued that only a video of Dick Cheney confessing would be enough to convince skeptics. However, your own response to the video I posted was not to accept this as evidence, but to question the validity of the video as evidence.
If this is, as clearly you believe, a reasonable response to a videoed confession, then the same criteria should also be applied to your proposed Cheney tape. Any video would be endlessly disputed and eventually probably discounted, in the same way any truther would (and you did).

 

[tfk]

I do know that the motions of out and then down are observed throughout the collapse.

Proof: https://youtu.be/AJf7pWVyvIw?t=314

Absolutely wrong

The initial motion was downward, in the form of tilting of WTC2, as easily seen in dozens of videos, such as here.

For good views of the sequence, start the video at 0:56, and then at 1:11.



There is no outward motion before the upper block begins to descend.

The pressure waves, blowing debris outward, occurred subsequent to the downward motion. It happens because over 400,000 ft³ per floor of air need to go somewhere. Late in the collapse, when the floors are failing at about 10 floors/second (or 0.1 seconds/floor), then 4,000,000 ft³/second of air must be pushed out of the way.

The proof that a substantial portion of this air was pushed downward, inside the lower portion of the building in front of the collapse front, and was therefore responsible for the emitted "squibs" (that aren't squibs at all, but air pressure waves), is that the fires in the upper floors of WTC1 brightened noticeably, as did smoke ejected from these floors, as WTC2 collapsed. There were also firefighters in the WTC1 stairwells that reported extreme winds that threw them around, coming UP the stairs at the time of WTC2 collapse.

All of the above happened because of the air pushed up WT1 by the collapse of WTC2. The two towers were joined, below street level, by several service tunnels. Some of the air pushed downward. Some pushed outward. All of the air was pushed towards its path of least resistance. (An effect that occurs for liquids, gasses and particulate matter that behaves like liquids. The use of that phrase, "taking the path of least resistance", for solids or structures demonstrates ignorance.
__

It is simple to prove that there was no "outwards, then downward" motions:

The FIRST motion was downward. And that downward motion never stopped.

In order for any subsequent outward motion to precede any downward motion, the downward motion would have to have been stopped at some point.

Video analysis PROVES that, during the entire time that the upper blocks were visible, there was NO time in which the collapse stopped after it had begun.

Ergo, it is proven that there was no time that any outward motion of air, or debris or structural components preceded any downward motion.

 

[Cosmic Yak]

His "confession" does not disprove CD.

The more I think about this, the more extraordinary this statement seems to be. False Flag, you are saying that a video of Bin Laden acknowledging that the attacks were an Al Qaeda operation does not prove CD.
Firstly, by the same logic, a video of Dick Cheney confessing would not rule out Al Qaeda involvement.Once again you have undermined your own argument. You really should stop doing this.
Secondly, in terms of the actual attacks, how does that work, then? You have already stated that you believe both thermite and explosives were used to bring down the buildings. If you also believe that Al Qaeda flew two planes into those buildings, perhaps you could explain how these two events were orchestrated? Did the US government (and, yes, you do think it was them, otherwise why mention Dick Cheney confessing?) plant the explosives, and then let them off just as the planes hit? Did Al Qaeda plant the explosives, and then fly planes into the buildings just to make sure? How did all the wiring and fuses survive the plane impacts?
So as to be fair, we'll use your own standard of proof. Could you link to a successful experiment showing how this could be done?

 

[Dave Rogers]

Secondly, in terms of the actual attacks, how does that work, then? You have already stated that you believe both thermite and explosives were used to bring down the buildings. If you also believe that Al Qaeda flew two planes into those buildings, perhaps you could explain how these two events were orchestrated?

http://xkcd.com/690/

Dave

 

[FalseFlag]

Has anyone performed an experiment to prove that Cole's conclusions are wrong?

If so, can someone please point me to it? There's like over 3000 posts in these two threads, and I haven't been able to find any experiments that prove Cole is wrong. It seems like it would be so easy. I mean, there are so many posts with words claiming Cole is wrong, so there must at least a few posts with experiments to support those words. Right?

I mean, I just saw a thread that lists the credentials of many of the skeptics here. It seems like with all that "expertise", performing one experiment proving Cole is wrong should be an easy task to accomplish. Right?

 

[Mark F]

Has anyone performed an experiment to prove that Cole's conclusions are wrong?

Not right or wrong, irrelevant.

 

[FalseFlag]

Not right or wrong, irrelevant.

So, in your world, an experiment that replicates the motions observed during the collapse of two 110 story buildings is irrelevant?

Got it. Thanks for publicly saying that and clearing it up for everyone.

 

[DGM]

Has anyone performed an experiment to prove that Cole's conclusions are wrong?

Why would anyone bother? Is there anyone actually paying attention to Cole?

You do know this is an election year? If your cause had any following, someone would have picked it up. You got nothing.