Can 15 floors crush one floor?

[Tony Szamboti]

Jeebus.

I know many of you folks have discussed the ROOSD mechanism on many occasions.

So why are you walking down the "block head" route...again ?!

There's not really an "upper block" impacting a floor below. 1D virtual simplified nonsense.

There's no rigid "upper block" either.

There's no reason to expect "jolts" to be recordable at the roofline. (Though by miracle/excellent tracing methods...a couple of "mini jolts" were found many many moons ago)

There's no way for vertical columns to experience any axial impacts. More 1D virtual nonsense.



And for the "record" early ROOSD mechanism testing indicated (via use of simple 1D inelastic collision models no less) that simply the mass of 3 OOS regions (not the core, not the perimeter, just the OOS floor and contents) dropped through a single storey height...would be enough to initiate a ROOSD-type propogation...to ground...

[qimg]http://femr2.ucoz.com/_ph/1/2/298826428.jpg[/qimg]

Not all this is for you Tony, but remember it was you who helped determine the energy requirement to shear the OOS region from its supports, so ...


Rigid "upper blocks", axial column impacts, jolts, blah de blah...all nonsense.


If you're not aware of ROOSD, there's plenty threads both here and at the911forum.

No excuse for the "hamster-wheel" going on here.

I don't doubt for a minute that what you prefer to call ROOSD would occur after several floors were collapsed and the quasistatic overload of multiple floors would continue to collapse the floors. However, that isn't what is going on in the first two to three stories of the collapse. Let's see if we can walk and chew gum here.

 

[Justin39640]

I don't doubt for a minute that what you prefer to call ROOSD would occur after several floors were collapsed and the quasistatic overload of multiple floors would continue to collapse the floors. However, that isn't what is going on in the first two to three stories of the collapse. Let's see if we can walk and chew gum here.

Right, cause 15 stories should drop 12 feet and come to a precarious rest while everyone wipes their brows and, in unison, say "that was a close one".

Please...

 

[Newtons Bit]

Jeebus.

I know many of you folks have discussed the ROOSD mechanism on many occasions.

So why are you walking down the "block head" route...again ?!

There's not really an "upper block" impacting a floor below. 1D virtual simplified nonsense.

There's no rigid "upper block" either.

There's no reason to expect "jolts" to be recordable at the roofline. (Though by miracle/excellent tracing methods...a couple of "mini jolts" were found many many moons ago)

There's no way for vertical columns to experience any axial impacts. More 1D virtual nonsense.



And for the "record" early ROOSD mechanism testing indicated (via use of simple 1D inelastic collision models no less) that simply the mass of 3 OOS regions (not the core, not the perimeter, just the OOS floor and contents) dropped through a single storey height...would be enough to initiate a ROOSD-type propogation...to ground...

[qimg]http://femr2.ucoz.com/_ph/1/2/298826428.jpg[/qimg]

Not all this is for you Tony, but remember it was you who helped determine the energy requirement to shear the OOS region from its supports, so ...


Rigid "upper blocks", axial column impacts, jolts, blah de blah...all nonsense.


If you're not aware of ROOSD, there's plenty threads both here and at the911forum.

No excuse for the "hamster-wheel" going on here.

I can't believe the term "ROOSD" is still being used. The engineering world just causes it "progressive collapse". Sometimes I hope the truthers and 9/11 researchers would catch on to that.

Anyways, what exactly is the x-axis of that chart? Time? Energy? Number?

 

[Oystein]

My prediction was mostly correct: Tony didn't say what distance if fall would give the top 15 floors enough momentum to crush 1 floor beneath, nor did he propose a method to determine that distance.

Oh well.

I'll reply to the things he did offer as an answer in reverse order:

Finally, the difference in length with the 207 foot wide face tower section with a 1 degree tilt would have been (207) - (207 x cos of 1 degree) = 0.0315' = 0.378".

Right - or about 1 cm, as I said.

The initiation occurred in the North Tower at the 98th floor and the perimeter columns were 14" square with 7.5 mm webs and flanges at the 97th floor with spandrel beams behind them.

Sounds correct.

7.5 mm is less than 0.378". Which part is parallel to the facade - web or flange? I am neither an engineer nor a native speaker... That part on the lower block end would be totally passed by by its counterpart on the top block, and instead of perimeter columns having an effective area of about 4 x 14" x 7.5 mm, this hypothetical meeting of top- and bottom column end would see only 2 x 7.5 mm x 7.5 mm.

The core columns were larger in most cases and would have had less misalignment since they were closer to the north face fulcrum. There clearly would not have been any misalignment significant enough to cause them to miss each other. The lateral inertia of the upper section would keep them aligned.

Never mind core columns at this stage. You have already proven that perimeter column misalignment will reduce effective load-bearing colukn area by almost 99%.

So the only way it could happen is with enough tilt, which can be shown not to be there. Those who say the columns would have been misaligned have nothing technical to back what they say. They are actually talking out of something other than their mouth.

No. I just take the numbers you just provided. 1° tilt will cause perimeter columns to effectively miss each other.

But that doesn't matter. The top block fell, therefore columns across a floor area were disconnected, and nothing will ever bring them back into contact again. Almost all of the momentum goes into the floors, which are not designed to carry that sort of load even statically - and that is observable reality.

First, transfer of momentum requires a deceleration on the part that is transferring it. There is no deceleration in the North Tower's fall measurement.

I seem to remember that the Szamboti-Chandler data in the "Missing Jolt" paper is perfectly consistent with actual jolts. Did you forget that you have been schooled on this?

The deceleration required for a gravity driven collapse would have been at least about 3g's.

WRONG. Most definitely not. If all columns that disconnected did magically make 100% contact again with their counterparts, AND that simultaneously, THEN there would be 3 g's at the level where columns meet - and less if you measure somewhere elso on the flexible assembly.




Tony, what are you doing here? Even I, a non-engineer with only medium interest in this debate of collapse details, have no problem seeing how terribly wrong you are. What is it with you? Who do you think you are fooling?

 

[jaydeehess]

Right - or about 1 cm, as I said.

See thats where you went astray Oystein. Its actually much closer to 1.5 cm

 

[Animal]

Tony, what are you doing here? Even I, a non-engineer with only medium interest in this debate of collapse details, have no problem seeing how terribly wrong you are. What is it with you? Who do you think you are fooling?

Facts cannot get in the way of the troofer cult religion

 

[Tony Szamboti]

My prediction was mostly correct: Tony didn't say what distance if fall would give the top 15 floors enough momentum to crush 1 floor beneath, nor did he propose a method to determine that distance.

Oh well.

I'll reply to the things he did offer as an answer in reverse order:


Right - or about 1 cm, as I said.


Sounds correct.

7.5 mm is less than 0.378". Which part is parallel to the facade - web or flange? I am neither an engineer nor a native speaker... That part on the lower block end would be totally passed by by its counterpart on the top block, and instead of perimeter columns having an effective area of about 4 x 14" x 7.5 mm, this hypothetical meeting of top- and bottom column end would see only 2 x 7.5 mm x 7.5 mm.


Never mind core columns at this stage. You have already proven that perimeter column misalignment will reduce effective load-bearing colukn area by almost 99%.


No. I just take the numbers you just provided. 1° tilt will cause perimeter columns to effectively miss each other.

But that doesn't matter. The top block fell, therefore columns across a floor area were disconnected, and nothing will ever bring them back into contact again. Almost all of the momentum goes into the floors, which are not designed to carry that sort of load even statically - and that is observable reality.


I seem to remember that the Szamboti-Chandler data in the "Missing Jolt" paper is perfectly consistent with actual jolts. Did you forget that you have been schooled on this?


WRONG. Most definitely not. If all columns that disconnected did magically make 100% contact again with their counterparts, AND that simultaneously, THEN there would be 3 g's at the level where columns meet - and less if you measure somewhere elso on the flexible assembly.




Tony, what are you doing here? Even I, a non-engineer with only medium interest in this debate of collapse details, have no problem seeing how terribly wrong you are. What is it with you? Who do you think you are fooling?

It is incredible that you think the column flange and web areas have to hit exactly square area to area to cause a deceleration and then to top it off you have the nerve to question me. This is precisely why people like you don't get answered. Go play in a sandbox somewhere.

 

[ozeco41]

I can't believe the term "ROOSD" is still being used. The engineering world just causes it "progressive collapse".

Not quite so.

"Progressive collapse" is a generic term. What happened with WTC1 and WTC2 on 9/11 had specific characteristics. A lot of the confusion in discussing WTC1/2 collapse comes from people being unclear whether they are discussing generic abstracts or specific to WTC on 9/11 realities.

ROOSD is a specific name applied to the specific mode of collapse progression which actually occurred at WTC on 9/11. I have no hang-ups that Major_Tom invented the term nor in acknowledging that he has done a lot of great work in describing the details of the WTC collapses. I don't subscribe to the motivation common around here that what M_T says must be wrong because we think he was a truther X years ago. (Nor am I suggesting that you subscribe to that falsehood - I'm just making sure that I am explicitly clear for other members.)

Now the approaches to explaining the WTC Towers collapses fall into two camps:
1) Approaches from abstract analyses including the "one dimensional" ones which femr2 advises we see beyond; AND
2) Approaches from analysis of what really happened in actual mechanism.

I have already cautioned posters in this thread to be clear which model they work from. And, read the thread, lots of gloss over the distinction.

I happen to prefer the approach working from what really happened. So does Major_Tom with his labelling of it as "ROOSD". I will use abstract Bazant material if I need it and it can be validly applied to the real events. And I'm not scared to take on God if God is wrong but let me not divert into "Valid Scope of Bazant" at this point.

Now as far as I know no-one from the "engineering world" has published explanations of "progressive collapse" which detail the exact mechanism rather than an abstract approximation. I may be wrong - let me know if I am please BUT I am only aware of analyses from the "abstract model" camp.

So, if you know of any, please give me links and I will add to my knowledge base. And see if their explanations add to my basic outline explanations published 2007-8 or Major_Tom and his associate's published later, but the same mechanism and labelled by him ROOSD and in lots more derail.

So the bottom line is that IMO femr2 is better served by the label ROOSD because the "engineering world" (excluding poor lonely little me if you are right ) which may prefer the generic term "progressive collapse". BUT femr2 is referring to specifics of what happened AND contrasting that specifically to the "abstract" alternate explanations. The "engineering world" has not explained the Twin Towers progressive collapses other than by abstract modelling. femr2 refers to the mechanism which actually and his distinguishing the two is legitimate. You may have valid reasons for disagreeing but that is a different issue so please don't beg the question that there is no distinction.

So if you know of, shall we call them, "examples of more legitimate descriptions of WTC Twin towers progressive collapse" please let me have the references.

So IMO your wish:

Sometimes I hope the truthers and 9/11 researchers would catch on to that...

...would be a backward step. We already have two more of less complementary paths leading to better explanations for WTC Towers collapses. Why destroy the positive distinction we have progressed to? Do we need to revert to total confusion?

And, If it is merely resistance to Major_Tom's acronym that concerns you - join me in my jealousy that I didn't think of a better one before M_T. 'coz I think he has won the "marketing image" race. Who knows, if I had thought of "ROOSD" back in 2007 maybe I would be getting picked on instead of M_T or femr2.

BTW this was the very rough graphic I used - 24 Nov 2007:

...I still wish I had called it ROOSD or some other catchy acronym.

 

[Justin39640]

It is incredible that you think the column flange and web areas have to hit exactly square area to area to cause a deceleration and then to top it off you have the nerve to question me. This is precisely why people like you don't get answered. Go play in a sandbox somewhere.

In your sandbox it seems the lower portion hasn't sustained any damage prior to its initial contact with the top section, that just fell 12 feet, and is damaged.

I live in the real world where, when big things break, chaos ensues.

 

[ozeco41]

I don't doubt for a minute that what you prefer to call ROOSD would occur after several floors were collapsed and the quasistatic overload of multiple floors would continue to collapse the floors....

Good to hear.

I will take out the "quasistatic" which I don't think is necessary - whether I understand it or not.

But this is an interesting challenge:

.. However, that isn't what is going on in the first two to three stories of the collapse. Let's see if we can walk and chew gum here.

Do you want to lead off with your explanation, do I go first or do we toss a coin?

Or is the offer only open to femr2?


It is quite some time since I needed to explain the transition from "initiation" to "progressive collapse"...

... in the ROOSD form as happened at WTC Twin Towers. (Sorry for the pedantry but see my previous post.)

 

[femr2]

I don't doubt for a minute that what you prefer to call ROOSD would occur after several floors were collapsed and the quasistatic overload of multiple floors would continue to collapse the floors.

Then why are you talking about something else ?

Thread title... can 15 floors "crush" one floor ?

Sounds very much like you are saying "yes".

Further than that, you're saying "several" rather than 15 would suffice.

However, that isn't what is going on in the first two to three stories of the collapse.

That's not the question Tony.

And, as you know, the first few feet are still a bit unclear.

However, you really need to sort out the silly axial impact stuff, "jolts" propogating through 150ft of CLEARLY deforming structure made of hundreds of different elements, to the NW corner, ...not a 1D world Tony.

Simply DIDN'T happen, as you know. The only problem you have there is why not.

A very simple, and observable "why not" is that at no observable point did any of the perimeter columns from "up top" hit any perimeter columns from "down below", on any observable face of the building. Instead perimeter columns are seen to pass each other (observed, on every observable face). That also has the implication of enough lateral motion for core columns to be doing the same, but obviously we can't easily observe that.

Have you ever measured lateral motion ? (I can't remember doing so, but I reckon it might be a pretty darn good idea to)

Have you ever bothered to recalc your expected scale of "jolt" taking into account everything, nay anything, it's been suggested (quite rightly) that you do ? Nope

Let's see if we can walk and chew gum here.

No problem. You've answered the OP question as far as I can see. I suggest that if it's seen by you as an opportunity to repeat the same story about missing bleedin' jolts that really aren't expected to be there imo, then we're likely to have a bit of a whiney conversation.

Much better for both of us if you start incorporating real and true and provable (by direct observation) factors in your calculations. Step 1...remove perimeter column impacts completely from your jolt calculations.

 

[femr2]

I can't believe the term "ROOSD" is still being used.

Why ? It's specific to the WTC.

The engineering world just causes it "progressive collapse".

Sub-classifications not made ?

Anyways, what exactly is the x-axis of that chart? Time? Energy? Number?

What it says on the axis..."connection failure"...the energy, in Joules, required to sever all connections between an OOS floor assembly from the perimeter and core.

Would have thought my words immediately beneath the graph you quoted...

Not all this is for you Tony, but remember it was you who helped determine the energy requirement to shear the OOS region from its supports, so ...

...would have given you some indication, but ho hum.

The other axis is the time for progression to ground. No datapoint for connection strength/floor mass qty that don't propogate to ground.

 

[femr2]

ROOSD is a specific name applied to the specific mode of collapse progression which actually occurred at WTC on 9/11.

Specific to post initiation propogation mechanism, yes.

Now as far as I know no-one from the "engineering world" has published explanations of "progressive collapse" which detail the exact mechanism rather than an abstract approximation. I may be wrong - let me know if I am please BUT I am only aware of analyses from the "abstract model" camp.

Sub-classifications would be interesting.

Why destroy the positive distinction we have progressed to? Do we need to revert to total confusion?

Tips hat.

 

[ozeco41]

It is incredible that you think the column flange and web areas have to hit exactly square area to area to cause a deceleration...

I have cautioned Oystein on the risk of joining you down in the detail - whilst letting you get away with wrong context or assumptions wrong. But you should thank him for playing at that level. He's a nice co-operative fellow.

However, on with the topic, because the reality is that, once the top section was falling - which happens to be your starting premise - the columns had already failed. AND the ends of those columns were already missing each other (or set up to miss) as I said in a previous post.

UNLESS - let no one claim I ignore logical possibilities.

Unless the bit of circular logic of the jolt that never was going to be there applies and some evil person had explosively/incendiary/any other method removed bits of column. AND even if that was true the end on end contact carrying significant load would not happen but we will never get to discussing that stage.....

... and then to top it off you have the nerve to question me...

Awkward beggar isn't he. Nearly as bad as me.

This is precisely why people like you don't get answered...

Yes we both ask questions you do not answer which we tend to interpret as "cannot answer".

...Go play in a sandbox somewhere.

And you confirm with your trademark of an insult to flag that the questions are too hard.

 

[Tony Szamboti]

Then why are you talking about something else ?

Thread title... can 15 floors "crush" one floor ?

Sounds very much like you are saying "yes".

Further than that, you're saying "several" rather than 15 would suffice.


That's not the question Tony.

And, as you know, the first few feet are still a bit unclear.

However, you really need to sort out the silly axial impact stuff, "jolts" propogating through 150ft of CLEARLY deforming structure made of hundreds of different elements, to the NW corner, ...not a 1D world Tony.

Simply DIDN'T happen, as you know. The only problem you have there is why not.

A very simple, and observable "why not" is that at no observable point did any of the perimeter columns from "up top" hit any perimeter columns from "down below", on any observable face of the building. Instead perimeter columns are seen to pass each other (observed, on every observable face). That also has the implication of enough lateral motion for core columns to be doing the same, but obviously we can't easily observe that.

Have you ever measured lateral motion ? (I can't remember doing so, but I reckon it might be a pretty darn good idea to)

Have you ever bothered to recalc your expected scale of "folt" taking into account everything, nay anything, it's been suggested (quite rightly) that you do ? Nope


No problem. You've answered the OP question as far as I can see. I suggest that if it's seen by you as an opportunity to repeat the same story about missing bleedin' jolts that really aren't expected to be there imo, then we're likely to have a bit of a whiney conversation.

Much better for both of us if you start incorporating real and true and provable (by direct observation) factors in your calculations. Step 1...remove perimeter column impacts completely from your jolt calculations.

You have no basis for saying a vertical analysis isn't legitimate. It is fully legitimate to look at the vertical descent only when it is known that there is no significant lateral movement. The upper 33 stories of WTC 7 had a significant deceleration after a 16 story fall and you have been shown that and I have explained the stiffness issue to you before.

It is only those with an agenda who inanely claim that no jolt would be expected and a few non-technical individuals who have gone along with it. The decelerations present in all of the measured Verinage demolitions should have shown anyone being honest about it, that may have thought different, that they were wrong.

 

[ozeco41]

Specific to post initiation propogation mechanism, yes.

Yes - and it does no harm to repeat it.

...Sub-classifications would be interesting...

I would settle for clarity of which classification people are talking about.....the sub-classes can come later.

Tips hat.

Thanks.

There was a bit of potential blue sky to deal with also.

 

[femr2]

You have no basis for saying a vertical analysis isn't legitimate.

I didn't say a vertical analysis was not legitimate.

It is fully legitimate to look at the vertical descent only when it is known that there is no significant lateral movement.

Well, I just had a quick look at old Sauret traces, and...a good 3 or 4 inches of Eastward lateral movement of the NW corner prior to NW corner release.

The upper 33 stories of WTC 7 had a significant deceleration after a 16 story fall

Irrelevant, and eh ?

Totally different descent mechanism imo.

Where is your "jolt" ...

16 storey ? What about after 1 ?

and you have been shown that

Nope. See WTC7 NW corner velocity graph above.

and I have explained the stiffness issue to you before.

Not satisfactorily, and certainly not taking into account that perimeter did not impact perimeter.

The critical question again...

What impacted what ? And when.

Add to that...whatever you think did impact...via what path and materials did that "jolt" have to pass through to reach the NW corner ?

It is only the untrained or those with an agenda who inanely claim that no jolt would be expected.

Nope. Show me perimeter impacting perimeter. I can show you the opposite.

The decelerations present in all of the measured Verinage demolitions

Utterly different mechanism, and irrelevant.

should have shown the untrained who were going along with the no jolt expected nonsense that they were wrong.

Absolute nonsense Tony, and you know it. You really do.

For WTC1...what exactly impacted what ?

I've just thrown 3 or 4 inches lateral motion on the table too...oh, and it increases to about 6 inches afterwards.

I'll retrace with current methods and give thee a graph'r'two.

 

[Tony Szamboti]

I didn't say a vertical analysis was not legitimate.


Well, I just had a quick look at old Sauret traces, and...a good 3 or 4 inches of Eastward lateral movement of the NW corner prior to NW corner release.


Irrelevant, and eh ?

Totally different descent mechanism imo.

Where is your "jolt" ...

[qimg]http://femr2.ucoz.com/_ph/7/2/135024800.jpg[/qimg]


Nope. See WTC7 NW corner velocity graph above.


Not satisfactorily, and certainly not taking into account that perimeter did not impact perimeter.

The critical question again...

What impacted what ? And when.

Add to that...whatever you think did impact...via what path and materials did that "jolt" have to pass through to reach the NW corner ?


Nope. Show me perimeter impacting perimeter. I can show you the opposite.


Utterly different mechanism, and irrelevant.


Absolute nonsense Tony, and you know it. You really do.

For WTC1...what exactly impacted what ?

I've just thrown 3 or 4 inches lateral motion on the table too...oh, and it increases to about 6 inches afterwards.

I'll retrace with current methods and give thee a graph'r'two.

I have shown you the jolt in WTC 7 before, as measured by David Chandler when he did the entire 18 story visible descent.

As for your 3 to 4 or even 6 inches of lateral movement on a 207 foot wide building making a difference, you can't be serious. It reminds me of your mini-jolt silliness that deserved nothing more than a big laugh.

For those who haven't seen what it is that should have occurred in a natural collapse of WTC 1, but didn't, here is a short video of a Verinage demolition vs. WTC 1 http://www.youtube.com/watch?v=NiHeCjZlkr8

If you notice there is plenty of lateral movement by the upper section and still a very measureable deceleration.

 

[femr2]

I have shown you the jolt in WTC 7 before

As I'm sure you know by now, my WTC7 trace data is particularly high quality, and I've just shown you a graph of the velocity.

Where is the jolt you are referring to ?

as measured by David Chandler when he did the entire 18 story visible descent.

David's data is not great Tony.

A bit like the missing jolt data.

Are you going to make me drag out "your" "missing jolt" data (which you didn't even generate) and critique in a similar way to that applied to the NIST trace data ?

(You've heard it all before of course, but never bothered to address any of it...years later...with data I've made freely available)

As for your 3 to 4 or even 6 inches of lateral movement making a difference, you can't be serious.

What difference did I say it made ?

I suggest it dwarfs the calculation you performed earlier about column alignment with a 1 degree tilt.

10cm > 1cm ?

It reminds me of your mini-jolt silliness that deserved nothing more than a big laugh.

Why ? I showed small jolts that were in the data, because they were there.

What exactly is silly about that ?

Certainly less "silly" than using low fidelity, low sample rate data taken from low quality video which has been processed incorrectly...to make conclusions, which, when questioned by supply of superior data...you ignore.

Perhaps you'd like to actually answer the rather relevent questions you've ignored...

1) What impacted what ? And when...or over what time period did the "many" "sub-jolts" occur ?

2) Whatever you think did impact...via what path and materials did that "jolt" have to pass through to reach the NW corner ?

3) What does 1 degree of tilt actually DO to your calculation ?

 

[femr2]

For those who haven't seen what it is that should have occurred in a natural collapse of WTC 1, but didn't, here is a short video of a Verinage demolition vs. WTC 1 http://www.youtube.com/watch?v=NiHeCjZlkr8

If you notice there is plenty of lateral movement by the upper section and still a very measureable deceleration.

Why not finish your post before you submit eh Tony.

Why can you not understand that floor<->floor impacts ARE going on for WTC1 ... of course (though not "flat" of course) ...they are simply occuring INSIDE the perimeter, as can be observed specifically by the large distance between the primary "crush front" and the trailing "perimeter peel" later in descent.

As far as I'm concerned there are large impacts going on within the perimeter (that ol ROOSD process) disconnected from the trailing desctruction. Serious "jolts" going on in there...just not directly connected to the bleedin' roof.

What impacted what ?