Szamboti's Missing Jolt paper

[boloboffin]

The upper block load needs to be amplified to overcome the factors of safety of the columns below for the collapse to continue.

This makes sense to me. The upper block load had been sitting on top of those columns for years. It was a static load and the structure below had been designed to redistribute it correctly. So something had to amplify that load to enable it to overcome the columns below.

That, of course, was the acceleration of gravity giving the load momentum. This amplified the load above into a dynamic load.

Please explain for everyone here how you think a load is amplified in an impulse. If you aren't sure you can say that instead.

Two ways -- the amount of time the load is applied can be lengthened, and the velocity of the mass applying the load can be increased. Gravity did the latter in this case. I see the upper section here contacting the floor below just long enough to tear the floor trusses apart and continue on down, so time applied may or may not be a factor here. I doubt the trusses held up long enough at all.

From you, we know that there were severe drops in acceleration of the upper section:

The smallest dip there is 25%, the biggest is 75%. The top level of acceleration there is 32 f/sec², which is the acceleration of gravity. So fairly quickly, the upper section is being virtually unimpeded in its fall, with the exception of those dips. That upper section is a juggernaut of mass, so when something is pulling the rate of acceleration down 75%, the upper block must be experiencing some significant resistance. The energy that would have been used to keep accelerating that upper section had to be going somewhere, Tony, and it had to be a heck of a lot. Where do you think it went?

I think it went to tearing up whatever was giving resistance to the upper block. But that's just silly old "B.A. in Bible, two years toward an M.A. in Christian Theology" atheist me.

Then we will see if I verified the "official story" or not.

Oh, you did.

This is your measurement of the Balzac-Vitry collapse. The roofline starts at zero, makes several dips in acceleration (while remaining in positive territory), then going into negative acceleration (never returning to positive territory), and finally returning to zero at the end of the collapse. That's two distinct phases of the collapse. The crush-down of the lower floors is the first phase, and the crush-up of the upper floors is the second phase, verifying Bazant's theory quite perfectly. Nicely done, Szamboti!

Don't chicken out, you are the one who opened your mouth about it.

Yeah.

 

[boloboffin]

I should point out that in the first section of the answer, I was a bit unclear. You aren't talking about collapse initiation, but collapse continuation. I realize that, and meant to make that clear. We're talking about an impact after the collapse has already initiated, when momentum is already building due to the acceleration of gravity.

 

[ozeco41]

The upper block load needs to be amplified to overcome the factors of safety of the columns below for the collapse to continue.....

No matter how many times you repeat that falsehood it remains false.

The outer tube columns below the inpact zone had limited involvement (only enough to support the shearing of the floor joist connectors if you accept the "no demolition" hypothesis AND even less if you accept the common conspracy theorists mode of global cokllapse).

The core coluimns mostly would have had limited involvement.

 

[leftysergeant]

And I am still waiting for a twoofer to tell me why the upper floors of B-V should not have bounced off, as per their theory that the tops of the towers should have bounced.

 

[Tony Szamboti]

This makes sense to me. The upper block load had been sitting on top of those columns for years. It was a static load and the structure below had been designed to redistribute it correctly. So something had to amplify that load to enable it to overcome the columns below.

Redistribute isn't really the right word concerning why an amplified load was needed to continue the collapse. The steel frame below was designed to take a significantly higher load than what was on it to provide a margin of safety.

That, of course, was the acceleration of gravity giving the load momentum. This amplified the load above into a dynamic load.

The load is not amplified due to the acceleration of gravity. The load would only be amplified if it transferred a significant amount of it's momentum due to impact. This amplification is measureable using gravity units. If it decelerates at 96.6 ft/sec/sec on impact then it decelerated at a rate of three times that of 1 g and thus the static load was amplified by three times.

Two ways -- the amount of time the load is applied can be lengthened, and the velocity of the mass applying the load can be increased. Gravity did the latter in this case. I see the upper section here contacting the floor below just long enough to tear the floor trusses apart and continue on down, so time applied may or may not be a factor here. I doubt the trusses held up long enough at all.

If the amount of time for load application is lengthened then you are lowering the shock by absorbing the energy over a greater time frame. This works against an amplification occurring. It is the columns which are the issue not the floors.

From you, we know that there were severe drops in acceleration of the upper section:

The smallest dip there is 25%, the biggest is 75%. The top level of acceleration there is 32 f/sec², which is the acceleration of gravity. So fairly quickly, the upper section is being virtually unimpeded in its fall, with the exception of those dips. That upper section is a juggernaut of mass, so when something is pulling the rate of acceleration down 75%, the upper block must be experiencing some significant resistance. The energy that would have been used to keep accelerating that upper section had to be going somewhere, Tony, and it had to be a heck of a lot. Where do you think it went?
I think it went to tearing up whatever was giving resistance to the upper block. But that's just silly old "B.A. in Bible, two years toward an M.A. in Christian Theology" atheist me.

There can be no amplification while the impacting object is still accelerating. The reason for the lower than g acceleration was that the number of columns left intact during the demolition could not support the static load, but still provided some resistance to full acceleration at the rate of gravity.

This is your measurement of the Balzac-Vitry collapse. The roofline starts at zero, makes several dips in acceleration (while remaining in positive territory), then going into negative acceleration (never returning to positive territory), and finally returning to zero at the end of the collapse. That's two distinct phases of the collapse. The crush-down of the lower floors is the first phase, and the crush-up of the upper floors is the second phase, verifying Bazant's theory quite perfectly. Nicely done, Szamboti!

The Balzac-Vitry was allowed to fall relatively unimpeded for two stories or about 25 feet with columns of those stories being pulled. At impact it was both crush up and crush down due to load amplification of the upper block. The impact occurrs at 1.5 seconds into the fall and the roofline shows a marked deceleration unlike WTC 1, which simply keeps accelerating.

 

[Tony Szamboti]

No matter how many times you repeat that falsehood it remains false.

The outer tube columns below the inpact zone had limited involvement (only enough to support the shearing of the floor joist connectors if you accept the "no demolition" hypothesis AND even less if you accept the common conspracy theorists mode of global cokllapse).

The core coluimns mostly would have had limited involvement.

There is no basis for what you are saying here during the first collision between floors. The use of the tilt and missing of columns and all that is non-explanatory. The only way to explain the collapse continuation naturally is with a powerful impact occurring when the first two floors collided. There aren't many ways around it and that is why Dr. Bazant thought one had to have occurred. Unfortunately, that didn't happen as we now know.

 

[Bananaman]

Tony:

A powerful impact would have needed to occur when the first two floors collided to continue the collapse naturally. There aren't many ways around it.

I have a feeling that that might be the reason several people cleverer than you, in fact dozens of them, have written papers and articles and reports explaining that effect, that you're unaware of. Or at least, if you have looked at them they sent you cross-eyed with confusion.

Bananaman.

 

[boloboffin]

Redistribute isn't really the right word concerning why an amplified load was needed to continue the collapse. The steel frame below was designed to take a significantly higher load than what was on it to provide a margin of safety.

But redistribute is the right word to describe how a structure handles the load that is sitting on it above. A properly designed building is redistributing load all the time due to wind, people moving around, furniture and other office furnishings being moved in and out. One floor in WTC 2 had to be reinforced because Cantor Fitzgerald (IIRC) put in a UPS room with huge lead batteries. The design as is wasn't enough to have properly dealt with that long-term mass.

When the jets tore through both buildings, both buildings had to suddenly redistribute a lot of weight from the upper sections because of damaged and/or missing columns. When the upper sections finally broke free, the structure below would have had to redistribute the sudden impact of the upper section immediately in order to arrest the falling mass. I'm quite happy with my use of the term.

I don't think the design parameters of the WTC building anticipated having ten of the top floors falling down into the rest of the building. I'll be happy to look at any documentation of this you might have.

The load is not amplified due to the acceleration of gravity. The load would only be amplified if it transferred a significant amount of it's momentum due to impact. This amplification is measureable using gravity units. If it decelerates at 96.6 ft/sec/sec on impact then it decelerated at a rate of three times that of 1 g and thus the static load was amplified by three times.

Obviously there's a more technical meaning here that I'm missing for the term amplification. I simply take it to mean making the force larger. A stationary mass has less force than an mass in motion. We've used the brick-on-head example many times. The brick stationary on your head is one level of load, one that's easily dealt with by your head. The brick dropped on your head from ten feet is a different level of load, one less easily dealt with by your head. That's a larger force, and gravity is indeed the factor that has made that force from the same mass larger.

But the more you talk, the more I understand what you are saying, and the more I understand how wrong you are.

I believe now that the load would only be amplified enough to overcome the structure below, and when I say "the structure below", I mean immediately below. It will only be amplified to the point of overwhelming the structure of the floor below. If the load is too great to be redistributed, the structure fails and the upper section continues down to the next floor.

Your mistake is taking the 31g figure that you imagine Bazant has claimed to happened, done calculations for what a 31g amplification would look like in the falling mass, and then demonstrated that WTC 1 didn't demonstrate that 31g amplification.

But Bazant only said that 31g was available, if I am reading him correctly. The upper section was bringing 31g to a 3g party (the estimated load capacity of the lower section). And even this case was of Bazant's best case scenario, something he does not claim actually happened on 9/11.

It seems to me that you should not be looking for a 31g amplification, but a 3g one.

If the amount of time for load application is lengthened then you are lowering the shock by absorbing the energy over a greater time frame. This works against an amplification occurring. It is the columns which are the issue not the floors.

You asked what would amplify a load. The formula for force is basically velocity and time. Manipulating either variable will make the end result larger.

Tony, it is indeed the floors that are the issue, because the floors are the weakest link in this chain. Most of the perimeter columns didn't buckle at all. Most of the core columns didn't buckle at all. But the floor trusses were doing their best impersonation of the Flying Spaghetti Monster. Tear the floor trusses loose from either the perimeter or the core, and the building is simply unzipping itself all the way down.

There can be no amplification while the impacting object is still accelerating.

I don't think this is right. When a mass could be accelerating at g, but is only accelerating at a drastically lower rate, then that mass is delivering a force to another body, a force greater than that which the mass could deliver at rest. Unless there is some technical reason why amplification could not mean this larger-than-static load, I think you're hung up here.

The reason for the lower than g acceleration was that the number of columns left intact during the demolition could not support the static load, but still provided some resistance to full acceleration at the rate of gravity.

I showed you, from your own data, that there are significant quantities of missing energy in the downward descent. Something is keeping that much mass from accelerating at g. There is some significant work being done somewhere in that collapse. You think it was crumpling columns left over from the demolition. I say it was the debris edge ripping apart the floor trusses.

The Balzac-Vitry was allowed to fall relatively unimpeded for two stories or about 25 feet with columns of those stories being pulled. At impact it was both crush up and crush down due to load amplification of the upper block. The impact occurrs at 1.5 seconds into the fall and the roofline shows a marked deceleration unlike WTC 1, which simply keeps accelerating.

The collapse does indeed last longer than the two seconds you measured. I withdraw the statement.

 

[Tony Szamboti]

Obviously there's a more technical meaning here that I'm missing for the term amplification. I simply take it to mean making the force larger. A stationary mass has less force than an mass in motion. We've used the brick-on-head example many times. The brick stationary on your head is one level of load, one that's easily dealt with by your head. The brick dropped on your head from ten feet is a different level of load, one less easily dealt with by your head. That's a larger force, and gravity is indeed the factor that has made that force from the same mass larger.

The reason the brick falling from a height onto your head does so much more damage than one sitting on your head statically is that it's weight (force) is amplified by it's deceleration. If it only decelerates at 2g you will only feel it's static weight times two. If it decelerates at three times the rate of gravity or 96.6 ft/sec/sec then it's weight will be amplified by three times and that is the force you will feel. It could easily decelerate at a 5g to 10g rate or greater and that is why a brick falling on your head is quite dangerous.

Your mistake is taking the 31g figure that you imagine Bazant has claimed to happened, done calculations for what a 31g amplification would look like in the falling mass, and then demonstrated that WTC 1 didn't demonstrate that 31g amplification.

But Bazant only said that 31g was available, if I am reading him correctly. The upper section was bringing 31g to a 3g party (the estimated load capacity of the lower section). And even this case was of Bazant's best case scenario, something he does not claim actually happened on 9/11.

It seems to me that you should not be looking for a 31g amplification, but a 3g one.

If you look in the paper we discuss a 6g amplification which would allow for real overload considering the perimeter columns had a factor of safety of 5.00 to 1 and the fact that dynamic strength is a little greater than static strength. However, that amplification could not have occurred because there is no evidence of a 6g deceleration. There is no deceleration at all.

You asked what would amplify a load. The formula for force is basically velocity and time. Manipulating either variable will make the end result larger.

I think you mean the change in velocity with respect to the time the change took place over. That is the impulse momentum equation. However, just changing either one in anyway won't necessarily make the force larger. A shock occurs when large amounts of energy are delivered in a short time frame and the impacting object decelerates rapidly amplifying it's weight (force) on the impacted object. It has to decelerate at a rate of greater than 1g to amplify it's weight and the amplification is proportional to the ratio of the deceleration to gravity or how many g's.

 

[Grizzly Bear]

The reason the brick falling from a height onto your head does so much more damage than one sitting on your head statically is that it's weight (force) is amplified by it's deceleration. If it only decelerates at 2g you will only feel it's static weight times two. If it decelerates at three times the rate of gravity or 96.6 ft/sec/sec then it's weight will be amplified by three times and that is the force you will feel. It could easily decelerate at a 5g to 10g rate or greater and that is why a brick falling on your head is quite dangerous.

I believe I understand your point, but doesn't that assume that the object taking the hit is sturdy enough to cause any discernible deceleration before it fails? What happens when the ultimate strength is exceeded before that deceleration has completely manifested?

 

[boloboffin]

A challenge to you, Mr. Szamboti: Go back and measure the roofline of each frame of the Sauret video between 1.6667 s and 1.8334 s. You said in your paper that you had only measured every five frames. This is four frames more - not that onerous a task.

It is at that point that the roofline increases in velocity from 39.59 f/s to 39.60 f/s. That is a velocity gain of 0.01 f/s, not a heck of a lot, and it corresponds to the 75% dip in acceleration from g.

After all, your own calculations say... Oh, let me just quote:

A 6g impulse requires a deceleration of 193 ft./s2. With a velocity reduction of 21.84 ft./s and a 193 ft./s2 deceleration, the duration of this impulse would have been 113 milliseconds. As the graph shows, there would still be a quite obvious abrupt negative slope change, which is not seen in the velocity curve determined from the measured data.

The measurements were taken every five frames, or 167 milliseconds apart.

The impulse duration would have been 113 milliseconds, and yet you took measurements every 167 milliseconds. Wouldn't you be more likely to catch a 113 millisecond impulse by having measured every 3 frames, or at least having gone through every frame of this crucial time period?

A friendly wager is in order here. If you don't find a period of deceleration between 1.6667 s and 1.8334 s, I will use the image of your choice as an avatar here for a month (within JREF protocol, of course). However, if you do find a period of deceleration, you must wear the avatar of my choice for a week.

You will do us the favor of showing your work.

 

[Tony Szamboti]

I believe I understand your point, but doesn't that assume that the object taking the hit is sturdy enough to cause any discernible deceleration before it fails? What happens when the ultimate strength is exceeded before that deceleration has completely manifested?

The strength of the impacted object and the amount of deceleration possible are related.

In the case of a building there has to be a jolt/impulse to generate enough of a load to cause the failure of the columns below, which are designed to handle more than the load above them. That means there will be deceleration if the lower structure is caused to fail or there wouldn't have been enough of a load to cause the failure.

 

[Tony Szamboti]

A challenge to you, Mr. Szamboti: Go back and measure the roofline of each frame of the Sauret video between 1.6667 s and 1.8334 s. You said in your paper that you had only measured every five frames. This is four frames more - not that onerous a task.

It is at that point that the roofline increases in velocity from 39.59 f/s to 39.60 f/s. That is a velocity gain of 0.01 f/s, not a heck of a lot, and it corresponds to the 75% dip in acceleration from g.

After all, your own calculations say... Oh, let me just quote:



The impulse duration would have been 113 milliseconds, and yet you took measurements every 167 milliseconds. Wouldn't you be more likely to catch a 113 millisecond impulse by having measured every 3 frames, or at least having gone through every frame of this crucial time period?

A friendly wager is in order here. If you don't find a period of deceleration between 1.6667 s and 1.8334 s, I will use the image of your choice as an avatar here for a month (within JREF protocol, of course). However, if you do find a period of deceleration, you must wear the avatar of my choice for a week.

You will do us the favor of showing your work.

I'll answer more tomorrow as I need to get to bed. However, I want to answer your question on impulse time. That is calculated as the velocity drop of 21.84 ft./s divided by the deceleration required for a specific impulse. In the case of a 6g impulse it would be 21.84/193 = .113. You don't see the jolt just the after affects. It would take time for the velocity to recover to what it was prior to the jolt and if there is no observed velocity reduction then it can be deduced that no impulse took place. The recovery time would have been nearly a second at freefall speed and we had five data points during that time and there is no evidence of a velocity drop.

 

[Bananaman]

It's funny, but you know someone isn't just clutching at straws, but screaming, "I'm not waving, but drowning", when, swamped with awesome amounts of contrary evidence, they have to focus on a 'jolt' to try and bolster their bizarre theories. A jolt which has been explained over and over again in other threads. A jolt which wasn't even a jolt.

Is there a charity for such people? If there is I'm not contributing.

Bananaman.

 

[boloboffin]

I'll answer more tomorrow as I need to get to bed. However, I want to answer your question on impulse time. That is calculated as the velocity drop of 21.84 ft./s divided by the deceleration required for a specific impulse. In the case of a 6g impulse it would be 21.84/193 = .113. You don't see the jolt just the after affects. It would take time for the velocity to recover to what it was prior to the jolt and if there is no observed velocity reduction then it can be deduced that no impulse took place. The recovery time would have been nearly a second at freefall speed and we had five data points during that time and there is no evidence of a velocity drop.

Yes, yes. Does that mean you will be accepting the wager?

 

[Grizzly Bear]

The strength of the impacted object and the amount of deceleration possible are related.

In the case of a building there has to be a jolt/impulse to generate enough of a load to cause the failure of the columns below, which are designed to handle more than the load above them. That means there will be deceleration if the lower structure is caused to fail or there wouldn't have been enough of a load to cause the failure.

The failure mechanism however should also depend greatly on how the loads are applied, not simply based on the design loads for which these structures were normally expected to experience in their lifetime. The strength of the columns, and the connections that hold them in place are subject to vary with the nature of the load is it not?

 

[boloboffin]

The failure mechanism however should also depend greatly on how the loads are applied, not simply based on the design loads for which these structures were normally expected to experience in their lifetime. The strength of the columns, and the connections that hold them in place are subject to vary with the nature of the load is it not?

The core column in particular weren't designed to deal with lateral loads. The perimeter columns dealt with 100% of lateral load requirements for the building. The core columns dealt only with gravity loads.

 

[AZCat]

If you look in the paper we discuss a 6g amplification which would allow for real overload considering the perimeter columns had a factor of safety of 5.00 to 1 and the fact that dynamic strength is a little greater than static strength. However, that amplification could not have occurred because there is no evidence of a 6g deceleration. There is no deceleration at all.

I am interested in the source of your 5x factor of safety for the exterior columns. This isn't at all similar to what the NIST calculated (for reference, see NCSTAR 1-2A). Have you considered that this might be incorrect?

 

[WilliamSeger]

However, I want to answer your question on impulse time. That is calculated as the velocity drop of 21.84 ft./s divided by the deceleration required for a specific impulse. In the case of a 6g impulse it would be 21.84/193 = .113.

In other words, both the 6g deceleration and the 113ms are completely bogus, even if we allow the bogus use of the simplified model to analyze an event known to be different from that model. Under ideal axial loading conditions, and assuming lateral restraint was maintained, the columns could provide a 3g deceleration to the falling mass for less than 20ms before being pushed through their elastic limit.

 

[AZCat]

Jeez, I guess the gang's all here.