Merged Applicability of Bazant's model to the real world

[ergo]

Really? Newton's Third Law says that the upward force acting on a falling mass from the collision interface meeting intact building structure must always exceed the downward force of gravity acting on the falling mass, so as to produce a deceleration?

If you're unclear as to what Newton's Third Law describes, perhaps you should brush up on it yourself.

 

[ergo]

... it's all still mass and the upper mass is not stronger than the lower. It may have an initial advantage if it can actually "fall" through the plane impact zone (which it can't) but the advantage stops quickly as that initial impact is shared and transferred between the two colliding bodies. There is no further advantage to be had gravitationally because the lower block easily arrests the upper.

If you want a rational reasoned explanation say so and I will provide it. Otherwise I will leave this bit of meaningless tripe unanswered.

Yes, you can go ahead and provide a rational, reasoned explanation as to why my description above would not be probable, although I'm pretty sure we've all heard it before. It believe it has something to do with a man named Bazant and this supernatural source of kinetic energy he discovered two days after 9/11.

 

[Tony Szamboti]

Ok. Let's assume that all columns had the strength to carry 3 times their normal load. Let's assume all columns were in unblemished state. If a moving top block now falls onto all columns perfectly and absolutely simultaneously, then we would expect to see an (average) deceleration of -2g (for a very brief momentm, until columns are overloaded).
However if only half the columns impact, and the other half an instant later, we'd see only -1g, for twice as long.

But our assumptions are wrong, on several counts:
- Column-on-column impact would not be perfect, and not happen at all in several places
- Not all columns would still have their full strength, as thos impacted early on were already stressed by heat, sagging floors, etc.
- Impacts are not as vertical as the static loads the columns are designed for
- The factor 3 is possibly an overstatement. NIST assumes 1.667, IIRC.

If we correct all assumptions, we will probably find that the maximum expected deceleration would be much closer to 0 than -1g. Which increases the probability that your low sampling rate will miss that peak.

NIST determined the factor of safety for the maximum design load and that wasn't the actual load. The factor of safety against vertical collapse with actual in-service loads was 3.00 to 1 for the core columns and over 5.00 to 1 for the perimeter columns.

To cause failure in a column which can support 3 times the load above it requires more than 3 times the load, meaning at least a 3g deceleration (jolt) would be required.

Every single Verinage demolition shows a significant deceleration at impact between the upper and lower sections of the building and I haven't seen a good explanation as to why there wouldn't have been one in the measured fall of WTC 1, other than that the structural integrity was being removed in an unnatural way.

 

[Newtons Bit]

Only 15% were estimated by NIST to have been severed. The remaining 85% were not.

That number is from the plane impact. We're talking about what happens when global collapse ensues. It's a separate event. Hell, it's an event YOU brought up. Are you having problems following your own train of conversation?

There's a misconception by "d-bunkers" that, first of all, the upper block would "fall" through the 85% remaining columns, and secondly, that the imagined severing of the 15% damaged columns would produce a radical shift of the upper block, misaligning the remaining composition of columns.

How could they fall through themselves? What exactly do you think happens when a column buckles?

 

[femr2]

Tony,

Are you going to answer my questions ?

 

[beachnut]

...
To cause failure in a column which can support 3 times the load above it requires more than 3 times the load, meaning at least a 3g deceleration (jolt) would be required.

...

Bazant understands why your rhetoric, your failed ideas, your delusions are nonsense.

Please do like Heiwa, publish your nonsense. This is classic fail and you don't understand why.

Bazant model has what to do with your failed ideas? Are you on topic? How does your CD delusion dovetail with Bazant's model?

When are your office mates coming to help you?

 

[carlitos]

Thanks to those of you who explained this to me in layman's terms. Tony's belief appears to be faith-based.

Tony,
You quoted this text and then ignored it. Why is that?

But our assumptions are wrong, on several counts:
- Column-on-column impact would not be perfect, and not happen at all in several places
- Not all columns would still have their full strength, as thos impacted early on were already stressed by heat, sagging floors, etc.
- Impacts are not as vertical as the static loads the columns are designed for
- The factor 3 is possibly an overstatement. NIST assumes 1.667, IIRC.

If we correct all assumptions, we will probably find that the maximum expected deceleration would be much closer to 0 than -1g. Which increases the probability that your low sampling rate will miss that peak.

 

[Oystein]

NIST determined the factor of safety for the maximum design load and that wasn't the actual load. The factor of safety against vertical collapse with actual in-service loads was 3.00 to 1 for the core columns and over 5.00 to 1 for the perimeter columns.

To cause failure in a column which can support 3 times the load above it requires more than 3 times the load, meaning at least a 3g deceleration (jolt) would be required.

Every single Verinage demolition shows a significant deceleration at impact between the upper and lower sections of the building and I haven't seen a good explanation as to why there wouldn't have been one in the measured fall of WTC 1, other than that the structural integrity was being removed in an unnatural way.

Gregory Urich estimated the total mass of a WTC tower to be 288.100 metric tons. I don't recall if this includes basement levels - let's be careful and assume it does. Then that is an average of 2,500,000 kg/floor, or 630 kg/m2.

Safety factor 3 would mean that a live load of 1260 kg/m² would be factored in above actual live loads, instead of 420 kg/m² extra loads.

That is 4.5 high quality upright pianos per square meter.
My upright piano weighs 280kg, is 118cm high, and covers about 0.79m², that's 356 kg/m², or 1.27 pianos per square meter.
Factor 1.667 would mean we could stuff all floors fully with pianos, with 50% of the area having 2 pianos on top of each other.
Factor 3 means, we could fill the entire volume of the tower with pianos and not exceed the maximum load.

You may be right, but I am skeptic. Got a citation?

 

[Oystein]

Thanks to those of you who explained this to me in layman's terms. Tony's belief appears to be faith-based.

Tony,
You quoted this text and then ignored it. Why is that?

He responded to one of the four items.

 

[carlitos]

OK, so he ignored the important bits. My point was that your pianos don't matter if the columns are missing each other and otherwise compromised. He's still arguing based on a limiting case with perfect axial column impacts.

 

[Newtons Bit]

OK, so he ignored the important bits. My point was that your pianos don't matter if the columns are missing each other and otherwise compromised. He's still arguing based on a limiting case with perfect axial column impacts.

It's a little absurd, isn't it? The columns have drastically lower capacities if they are even off-set by an inch.

 

[Dave Rogers]

Every single Verinage demolition shows a significant deceleration at impact between the upper and lower sections of the building and I haven't seen a good explanation as to why there wouldn't have been one in the measured fall of WTC 1, other than that the structural integrity was being removed in an unnatural way.

Yes you have. I've offered you one several times. You've simply chosen not to read it. A simple tilt of the upper block, as observed in videos of the collapse, reduces the jolt below -1g, because the upper block is impacting sequentially rather than simultaneously. This doesn't happen in verinage demolitions because the collapse is controlled such that the supports are all removed over an equal length, and the upper block falls without tilting. It happened in the WTC collapses because they were uncontrolled.

I don't know why I'm bothering to post this, though. You've demonstrated beyond any possible doubt that you're either disinclined, or unable, to understand it.

Dave

 

[ergo]

That number is from the plane impact. We're talking about what happens when global collapse ensues. It's a separate event. Hell, it's an event YOU brought up. Are you having problems following your own train of conversation?

You said:

The only thing capable of supporting the weight of the upper block is the fully intact and braced columns of the lower block. When the collapse starts, the connection between the columns of the upper block and lower block has severed. The columns of the upper block fall, mostly, onto the floors of the lower block. The floors can't support it and they collapse.

How does the "connection" between the 85% remaining columns of the upper and lower blocks get "severed"?

And what happens when the columns of the lower block get pushed against the floors of the upper block? Does "global collapse ensue" upwards?

 

[Dave Rogers]

How does the "connection" between the 85% remaining columns of the upper and lower blocks get "severed"?

Lateral progression of column failure, as observed in videos.

And what happens when the columns of the lower block get pushed against the floors of the upper block? Does "global collapse ensue" upwards?

More or less irrelevant. The lower block is unable to support the dynamic load from the upper block, whether that block is a single intact unit, a composite of an intact unit and an intervening rubble layer, or a disconnected accumulation of rubble. The mass, momentum and kinetic energy are the same. Solving the differential equations of progressive collapse indicates that the downward collapse propagates and the upward collapse terminates for a specific simplified case, but there is no conceivable solution in which the downward collapse terminates unless debris is expelled faster than it's created, which is physically absurd.

Dave

 

[ergo]

Lateral progression of column failure, as observed in videos.

The videos show us one or two corner columns seemingly buckling--columns which would have, in reality, had a very difficult time buckling in because of their very placement. I have not seen videos showing a pulling inward of numerous columns, all in a row or sequence. Please point me to such if I have missed it.

More or less irrelevant. The lower block is unable to support the dynamic load from the upper block, whether that block is a single intact unit, a composite of an intact unit and an intervening rubble layer, or a disconnected accumulation of rubble.

You're merely repeating a belief here as if it's some kind of cause.

The mass, momentum and kinetic energy are the same. Solving the differential equations of progressive collapse indicates that the downward collapse propagates and the upward collapse terminates for a specific simplified case,

What you mean to say is, "Bazant shows it's possible mathematically to describe a gravitational collapse from these causes."

but there is no conceivable solution in which the downward collapse terminates unless debris is expelled faster than it's created, which is physically absurd.

It is simple, basic physics that would indicate that the downward collapse terminates. Gravitational energy would be expended, both upwards and downwards, in crushing each floor. You do not have a realistic model of physics that can support your bizarre notion of indefinite downward collapse through the path of greatest resistance. You are using anti-science.

If you disagree, please tell me which law of physics supports this notion of indefinite downward collapse through a path of greatest resistance.

 

[ergo]

What you mean to say is, "Bazant shows it's possible mathematically to describe a gravitational collapse from these causes."

This needs to be qualified by adding: "...if one ignores Newton's Third Law."

 

[excaza]

Yes, because that's exactly what Bazant did

This needs to be qualified by adding: "...if one ignores Newton's Third Law."

This needs to be qualified by adding: "Because I don't understand it..."

 

[ergo]

Yes, because that's exactly what Bazant did

Many things are possible mathematically that are not in reality. I'm sure the evolution of unicorns could be mapped and "proven" mathematically, but that does not bring unicorns into being.

This needs to be qualified by adding: "Because I don't understand it..."

Most of you do indeed appear not to understand Newton's Third Law. Either that or you're deliberately ignoring it for reasons unknown.

 

[excaza]

Most of you do indeed appear not to understand Newton's Third Law. Either that or you're deliberately ignoring it for reasons unknown.

Please save us, ergo, please publish a paper that REALLY explains what happened. Free us from the influences of The Man.


Or just back away from having to provide a theory like your pal Java Man did.

 

[femr2]

You're merely repeating a belief here as if it's some kind of cause.

It's not a *belief*. It's something that everyone needs to *get*.

I'll simplify it...

Your shiny new tower has floors attached to core and perimeter columns.

Even though the columns vary in strength and thickness, the connections between the floor and the columns don't vary. They are the same top to bottom.

Each floor can support up to 1 million Kg before the connections fail.


All clear ?


If we put over 1 million Kg on the floor, it's connections fail.


It doesn't matter whether that >1 million Kg is moving or not, or whether it's in one solid piece or pea sized chunks. It still weighs over 1 million Kg, and the floor connections cannot support over 1 million Kg.


So...


Let's drop 2 million Kg on the floor.


What happens ?