Szamboti's Missing Jolt paper

[Tony Szamboti]

That is simply not the truth, and you must know it isn't. Yes, your original paper did claim there should be 31g jolt, and you made that claim because you are the one who failed to consider the fact that the shock intensity would be limited by the strength of the columns below. Making that mistake is one thing, and a mechanical engineer should be embarrassed about it, but you should be thoroughly ashamed of yourself for that despicable post blaming your error on Bazant.

You are talking garbage.

I said in the very first version of the paper that a 31g impulse would have been impossible because at that magnitude the upper section would have come apart before all of it's mass could even participate. I did not mention the fact that the lower section would have prevented it also, but that point is moot as I recognized the fact that a 31g shock load was impossible with the structure.

 

[Tony Szamboti]

Will you PLEASE define the goddamn term? We can't help if you refuse to let us know what the hell you are defining a "jolt" as.
It is a meaningless term the way you use it.

Guinn, it might be best if we just call it a shock load. Does that work for you?

 

[leftysergeant]

I said in the very first version of the paper that a 31g impulse would have been impossible because at that magnitude the upper section would have come apart before all of it's mass could even participate.

Doesn't matter if it does come apart because it is, even in a dissasociated state, a geometric solid for most purposes. It has volumn, mass and weight. Unless it spills over the sides, it is still there to participate in the collapse.

 

[WildCat]

Doesn't matter if it does come apart because it is, even in a dissasociated state, a geometric solid for most purposes. It has volumn, mass and weight. Unless it spills over the sides, it is still there to participate in the collapse.

In the alternate universe truthers live in the mass vanishes once the structural integrity is compromised, and gravity ceases to be a force.

 

[Tony Szamboti]

Doesn't matter if it does come apart because it is, even in a dissasociated state, a geometric solid for most purposes. It has volumn, mass and weight. Unless it spills over the sides, it is still there to participate in the collapse.

Rubble would not have the same dynamic loading effect during impact as a connected solid. The rubble would act like a quasi-static load.

 

[rwguinn]

Guinn, it might be best if we just call it a shock load. Does that work for you?

Thank you. Now, we are working in the frequency domain, and have gotten that pesky time variable out of the picture.
Suppose you could post your required shock spectrum? The one that you think should have happened?

 

[leftysergeant]

The rubble would act like a quasi-static load.

So? As long as it is accellerating downward, it places added stress on the floors and tears them loose from the perimeter columns.

FAIL.

 

[WildCat]

Rubble would not have the same dynamic loading effect during impact as a connected solid. The rubble would act like a quasi-static load.

Irredicible delusion.

QED

 

[Tony Szamboti]

So? As long as it is accellerating downward, it places added stress on the floors and tears them loose from the perimeter columns.

FAIL.

It sounds like you don't know the difference between a dynamic load and a quasi-static load. It has to do with response and load amplification. Nobody is saying that rubble does not apply stress. The question is whether it can apply enough.

 

[WildCat]

It sounds like you don't know the difference between a dynamic load and a quasi-static load. It has to do with response and load amplification. Nobody is saying that rubble does not apply stress. The question is whether it can apply enough.

Are you still claiming the floors of the WTC could carry 725psf?

 

[Tony Szamboti]

Thank you. Now, we are working in the frequency domain, and have gotten that pesky time variable out of the picture.
Suppose you could post your required shock spectrum? The one that you think should have happened?

We have been dealing with the magnitude of the shock necessary, but I did calculate durations in the Missing Jolt paper which frequency can be found from for a shock load. It is just the reciprocal of twice the duration.

 

[R.Mackey]

It sounds like you don't know the difference between a dynamic load and a quasi-static load.

Pretty cheeky thing for you to say, given that I had to explain it to you, and that you still don't seem to understand how it applies here.

Also doesn't excuse your lies above about the contents of Bazant & Zhou (2002).

 

[leftysergeant]

Nobody is saying that rubble does not apply stress. The question is whether it can apply enough.

Just look at the connectors between the floor pans and the perimeter columns. Doesn't matter what part of the building they are from, they are all pulled inward and downward. The only way this can be done is by forcing the floor pans, as a unit, downward. There is no other mechanism available to do this than by dropping concrete slabs on them. NO explosiove device that I know of could slam concrete slabs down on each other without also throwing all manner of stuff, from office supplies and furniture to torn bodies out the windows, entraining tiny streamers of dust behind them. We do not see this in any video.

Before the lower portions of either tower begin to fail, we see at least four discreet puffs of dust from several locations. (Don't you even try to tell me they are explosive squibs. I am not that stupid or unfamiliar with explosive demolitions.) That the dust comes out in puffs clearly indicates a series of discrete events, obviously individual floor slabs falling on one another.

The load was sufficient to break the connectors. End of story.

 

[Tony Szamboti]

Just look at the connectors between the floor pans and the perimeter columns. Doesn't matter what part of the building they are from, they are all pulled inward and downward. The only way this can be done is by forcing the floor pans, as a unit, downward. There is no other mechanism available to do this than by dropping concrete slabs on them. NO explosiove device that I know of could slam concrete slabs down on each other without also throwing all manner of stuff, from office supplies and furniture to torn bodies out the windows, entraining tiny streamers of dust behind them. We do not see this in any video.

Before the lower portions of either tower begin to fail, we see at least four discreet puffs of dust from several locations. (Don't you even try to tell me they are explosive squibs. I am not that stupid or unfamiliar with explosive demolitions.) That the dust comes out in puffs clearly indicates a series of discrete events, obviously individual floor slabs falling on one another.

The load was sufficient to break the connectors. End of story.

We are discussing why there was no velocity loss observed in the fall of the upper section of the building here. Are you trying to a rubble load to that somehow?

 

[Tony Szamboti]

Pretty cheeky thing for you to say, given that I had to explain it to you, and that you still don't seem to understand how it applies here.

Also doesn't excuse your lies above about the contents of Bazant & Zhou (2002).

It is incredible that you would claim that you had to explain quasi-static vs. dynamic loads to me. I have been dealing with them for years in my work. You are full of bluster Ryan.

I am not lying about the contents of Bazant and Zhou. If you think I am why don't you explain it in detail with calculations.

 

[R.Mackey]

You can't possibly understand them, because you've consistently applied the concept wrong in this context for nearly three years.

Dr. Bazant never claimed there would be a 31 g jolt. No calculations needed. Just read the darn thing. You claim you have, in fact your whole enterprise is based on it, therefore you lied.

 

[leftysergeant]

We are discussing why there was no velocity loss observed in the fall of the upper section of the building here. Are you trying to a rubble load to that somehow?

There were two processes going on. The top sections did not come disconnected to initiated the collapse. They were clearly in contact at all times. The rubble just built up fast enough, with enough downward acceleration, to start peeling off perimeter columns before the top discombobulated entirely. The only thing that I can see that Bazant might have gotten wrong was that the crush-up started before the crush-down, and that the rubble thus generated drove the crush-down, not by crushing the columns, whether core or perimeter, but by bashing in the floors.

 

[WilliamSeger]

You are talking garbage.

I said in the very first version of the paper that a 31g impulse would have been impossible because at that magnitude the upper section would have come apart before all of it's mass could even participate. I did not mention the fact that the lower section would have prevented it also, but that point is moot as I recognized the fact that a 31g shock load was impossible with the structure.

BS! The earliest version of the paper I could find is online here.

Bazant claims that a minimum force amplification of 31g, or 31 times the static weight of the upper stories, would have occurred in a collision between the upper and lower blocks of the Twin Towers after a fall of one story. [17]
...
The graph below shows what the upper block velocity change would look like if a 31g impulse had occurred one story into the fall, with the its velocity momentarily reduced in a significant way after impact.

{Figure 5: Roof Velocity Curve with a hypothetical 31g deceleration}

The fact that a 31g impulse requires a deceleration of 997.4 ft./s² is unassailable, and it does not matter whether the collision is elastic or inelastic. With a velocity reduction of 13.13 ft./s. and a 997.4 ft./s² deceleration, the duration of this impulse would have been 13 milliseconds. This rapid deceleration associated with the 31g impulse would necessarily show itself as an abrupt negative slope change in the velocity curve. {Emphasis added}

We have shown the curve starting upward again after the impact, on the generous assumption that the impacting object (the upper block) is now free to accelerate unimpeded after impact. We have also only charted what the effect on the velocity should have been for an initiating impulse between the first two floors to collide.
...
17. Bazant and Zhou, 2002, p. 3.

And did Bazant and Zhou actually say there was a "minimum force amplification of 31g?" No, they did not:

So the loss of the gravitational potential energy of the upper part may be approximately equated to the strain energy of the lower part at maximum elastic deflection. This gives the equation mg[h + (P/C)] = P²/2C in which m=mass of the upper part (of North Tower) ~ 58*10⁶kg, and g=gravity acceleration. The solution P=P_dyn yields the following elastically calculated over-load ratio due to impact of the upper part:

P_dyn / P₀ = 1 + sqrt(1 + 2Ch/mg)) ~ 31 (1)

where P₀ = mg = design load capacity.

You and Graeme are the ones who completely misinterpreted Bazant's 31-times over-load ratio as a "force amplification of 31g" and equated that to a 31g deceleration, and you are the ones who calculated and graphed that bogus interpretation without realizing that the columns below could not possible offer more resistance than the force it took to fail them.

And you are the one who is still talking garbage, Tony.

 

[Seymour Butz]

And to flesh this out, there would have to be a direct column-to-column impact after collapse initiation, correct? Otherwise, no jolt?

But when columns buckle, or are pulled through verinage, they're not exactly in line anymore, are they?

Address this Tony.

 

[Tony Szamboti]

BS! The earliest version of the paper I could find is online here.



And did Bazant and Zhou actually say there was a "minimum force amplification of 31g?" No, they did not:




You and Graeme are the ones who completely misinterpreted Bazant's 31-times over-load ratio as a "force amplification of 31g" and equated that to a 31g deceleration, and you are the ones who calculated and graphed that bogus interpretation without realizing that the columns below could not possible offer more resistance than the force it took to fail them.

And you are the one who is still talking garbage, Tony.

Seger, you did not quote the part of the Missing Jolt paper on page 12 where I state

In reality, the upper block could not have tolerated the potential 31g impulse theorized by Dr. Bazant. To get this overload he claims was possible, all of the mass of the upper block would have had to participate, and if it did so it would have come apart completely.

Perhaps the impulse was of a lower value but still high enough to cause an overload of the lower structure and bring about global collapse? Consider a velocity graph with a 6g deceleration, very likely the minimum load amplification necessary to overcome the reserve capacity of the perimeter columns, which had a minimum factor of safety of 5.00 to 1.


You apparently also can't understand that when Dr. Bazant says


P = Pdyn yields the following elastically calculated overload ratio due to impact of the upper part: where Po = mg

and he calculates Pdyn/Po as 31, that this means Pdyn is an amplification of the static load (mg) of 31 times meaning a 31g deceleration would have had to occur for that to happen. I can understand your confusion somewhat as Dr. Bazant also calls Po the design load capacity but it isn't. It is just the static load. The design load capacity would be the static load x factor of safety. The 31g amplification would thus be an overload of 31/factor of safety.