Moderated Steel structures cannot globally collapse due to gravity alone

[Architect]

Hello Helloo

For the rest your comments are purely subjective and a waste of space.

I'm sorry, but what comments do you believe to be "purely subjective and a waste of space"? Are you just referring to those addressed to yourself or, for example, do you include my posts on fire performance of steel?

 

[Grizzly Bear]

funk,

We have been over this. Almost all of the load above the impact zone was on the core and exterior columns.

It would be physically impossible to put this load on the floor truss connections.

And when the core & exterior columns fail catastrophically in the region where they have been weakened by the combined effects of impact and heat exposure, what is taking the load of all of the floors above that point when it begins to accelerate in descent? When this section is skewing its footprint along the entire floor area as it tilts what must sustain that load in order to transfer it to the columns, and then to the ground? This should be an easy question to answer.

In a static state, the floor systems did several things; they A) carried the live and dead loads that were required for each individual floor B) they transferred these live and dead loads from everyday use to the core and perimeter columns C) and transferred lateral bracing between the core and perimeter columns.

In the dynamic state however this is not the case; the core has failed, remember? As the core is no longer able to carry its loads the hat truss at the top of the structure tries to transfer the weight to the perimeter columns, and in turn they cannot handle these new loads so they begin to fail. The building begins its descent and the first thing it meets is the floor system immediately beneath it, which now must not only hold its design loads, but also the weight of 15 other floors' worth of structure (north tower) or 29 other floors' worth of structure (south tower) respectively. These loads must first be transferred to the connections, THEN in turn to the core and perimeter columns. Now what happens when the loads overwhelm the floor system before it can efficiently transfer its loads to the appropriate pathway?

The collapse clearly demonstrated that what failed and helped to progress the collapse was a domino effect in which the floors failed successively when they could not carry the loads they were subjected to. The core columns being the last structural components to completely fail only demonstrate this further.

 

[bill smith]

I'm sorry, but what comments do you believe to be "purely subjective and a waste of space"? Are you just referring to those addressed to yourself or, for example, do you include my posts on fire performance of steel?

No I was only addrssing the comments that he made in that particualar post, though I could have done so with many of his other posts as you will have doubtless seen. I was of course not addressing you or your posts in any way at that time.

 

[tfk]

OK, you guys have been asking for this. Here ya go.

A completely viable mechanism for the collapse to have tossed a 4 ton external support 600+ feet. Note that this mechanism uses a lever technique.

For the purposes of description, the term "unit" will refer to a 3 column and 3 spadrel assembly. The building is on the left, and it is going to toss a unit (hereafter referred to as Unit B) to the right. Unit A will be the unit directly above B, and Unit C will be the one directly below.

There are only two simple geometries that are required.
1) there be a pivoting moment on Unit B that attempts to kick its bottom outward, and
2) that there be some piece of debris that lodges against the upper end of Unit C that prevents its upper end from sliding inward as Unit B descends.

That's it. This is a highly probable pair of conditions to exist as the tower collapses. Given these two SIMPLE conditions, Unit B will be snapped off from Unit A and hurled to the side, as described below. The closer the top of Unit C is to the Unit A / Unit B junction when its bolts fracture, the faster Unit B will be tossed to the side.

With this simple geometry, Unit B can be tossed at any angle, with horizontal being 0°, straight downward being -90° and straight upward being +90° and at horizontal speeds 2 to 4 times the descent speed of the upper block. It is TRIVIALLY simple.

The situation begins with alternate multiple-unit vertical columns bowing outward, and the adjacent columns bowing inward. This action snaps the lateral connections between Unit B and its horizontally adjacent units. Several vertical columns were seen in this configuration immediately prior to the collapse. Units A, B & C are on the same column, which was bowing outwards.

The next event is the initiation of collapse event. This evert results in the snapping of the bolts connecting units B & C. When the fracture occurs, the the bottom of Unit B drops to the outside of the top of Unit C, and begins to descend.

As Unit B moves down on the outside of unit C, it is attached to Unit A only. As the upper block moves down, the top of Unit B is located inboard (ie., towards the building) of the top of Unit C, and attempting to pull it inboard. Suddenly, some piece of debris lands on the inside of Unit C, preventing it from moving inboard. This forces the top of Unit C to begin to act as a fulcrum point for Unit B. As Unit B descends with its 3 floors attached, the top of Unit C successively shears off the 3 welds that join the Cross Trusses hangers to the spandrel of Unit B. It would take about 1.83 seconds for Unit B to fall 3 1/2 stories (43') at (for example) 0.8 Gs, Unit A, B & everything attached is moving downward at ~47 ft/sec.

As Unit B descends on the outside of Unit C, the bottom of Unit B begins to pivot away from the building, with the top of Unit C acting as a pivot point. The junction between Units B & A is being driven down inside of Unit C, and the lower part of Unit B is accelerating outward. At the same time, it is forcing units A & B to pivot at their juncture. Finally, the bolts joining Units A & B will fracture. If the location of the pivot point (i.e., the top of Unit C) is approximately 9 feet from the top edge of Unit B, then the Center of Gravity of Unit B will be swinging outward at the same velocity that the top edge of Unit B is moving downwards (i.e., 47 ft/sec). If the pivot point is closer to the top of Unit B, then the CG will be moving faster outward then the AB junction is moving downward. If the pivot point is 6' from the top of B, then the CG will be moving twice as fast (i.e., 94 ft/sec = 64 mph. If the pivot point is 4.5' from the top of Unit B, then the speed of the CG will be 3x the downward speed of the upper section (i.e., 141 ft/sec = 96 mph).

All of the above seems to me to be not only possible. It seems inevitable.

This is only one of dozens of possible events that one might imagine throwing debris far distances outside of the towers during their collapse.

tk

 

[L The Detective]

A child can see WTC 7 fall straight down at near free fall [actual free fall for the first 105 feet]. Buildings don't do that unless they are CD's. It is not necessary to have any other information. There is no other explanation for a building falling the way WTC 7 did.

Isn't it possible that what you and the hypothetical child percieve to be "freefall" in the video is actually not freefall? Don't you think that there's room for you and 12 year old children to be wrong about this conclusion? If not, why not?

I'm not attacking you; this is meant to be an honest question.

 

[tfk]

Chris,

[intended statement] The fact that you do not understand something does not make it "double talk".

The fact that you don't understand something does make it "double talk".

Chris, I don't think that I've insulted you. If I have, I apologize. But i would appreciate if you show the same restraint.

As I mentioned, I AM a mechanical engineer with a 34 year, successful career doing it. I'll be happy to explain things to you as long as don't get snarky. I have truly had enough of that nonsense from twoofers.

I specifically did not get into "how to release" it.

Until you do you haven't shown that it is possible to use this stored energy to eject a beam laterally.

It was not my intention to show how it could be done. It was my intention to show that it is NOT, as CTers have claimed, IMPOSSIBLE.

This is the type of specious argument that you've been bringing up constantly. The SPECIFIC question that ole bill was jabbering about (it turns out incorrectly) was that there was "only enough energy storage capability in a steel box column, without kinking, to be thrown a couple dozen feet. But never 200, 400 or 500 feet."

I am not an engineer or mathematician but excuse me if I don't accept your analysis without some verifiable conformation.

I assume you meant "confirmation". The confirmation is trivial. You bend metal. Energy gets stored in the atomic distortion of the metal. When the external forces on the metal are released, the atomic structure returns to its undistorted, lowest energy configuration. This is the essence of the action of a spring. All of the above is incontestable. It is mechanics 101.

The only thing that you might question is "did I calculate the amount of deflection of the beam (while staying in the linear range) and the amount of energy stored correctly?"

The answer is "yep, I did". The calculations are trivial. After designing deflecting members for years (connectors, snap fits, etc.), I've got a good feel for what these numbers are. 5.3" of deflection for a 14" square box column that is 37 feet long is completely reasonable.

The next task, how much force is required, is also relatively simple. It's called the "Stoney equation" or "Storey equation" IIRC. It relates the relationship between force and deflection for a cantilever beam.

Normally, I'd have to calculate the stress & strain at every point in the beam. This would be a bit complex. Not really hard, but involved. However, there is a simplifying trick due to a guy named Castigliano.

Castigliano's Theorem is a mechanical version of "conservation of energy". This says that the internal energy stored inside an element is equal to the external energy applied to it. And this number is trivially easy to calculate. For ANY spring acting in the linear range, the internal potential energy (PE) is given by: PE = 0.5 * F * d. Where F = force (pounds) and d = deflection (inches) and the PE is then given in inch-pounds.

As I calculated, if one were to intentionally devise anchoring system that would allow you to pull back on the beam & arc it like a bow, and then cut the string, then it WOULD fly out at about 75 mph (remember that 54 mph was for a cantilever beam. You can get twice as much energy stored in a uniformly arced beam, for 41% more speed. Remember, energy goes as speed squared.

What kind of lateral force do you get when neither end is attached?

None, of course. But for EVERY single one of those beams, in the instant before it was unrestrained, it WAS restrained as a part of the towers. And in the descending debris, there were infinite combinations of forces to be applied to column assemblies that were churning around in the collapse.

As a direct result of this horizontal speed, if you fling this from an altitude of 1000', it'll travel about 800' horizontally.

Hold on there cowboy, before you discuss how far it will travel, establish the conditions that could bend a 3 beam section to maximum energy storage, rip it loose and still use that stored energy to propel it laterally. Seems to me you can't get all these conditions to occur.

As I said, my purpose was only to show that it was NOT IMPOSSIBLE for the columns to have been thrown using internally stored energy only, which I already knew, and to get an BOTE estimate of how far that might be. My job is done with that.

But, as you'll see in my preceding post, I've described a completely viable mechanism for throwing a beam assembly over 600'.

You're welcome.

tom

 

[Architect]

Bill, Bob

I'm mindful that the US is some time behind us (and there may be a timelag induced by the moderated nature of the thread) but nevertheless would very much appreciate your responses to the various (6, last time I looked) response to the substantive points put to you.

 

[Christopher7]

And when the core & exterior columns fail catastrophically in the region where they have been weakened by the combined effects of impact and heat exposure, what is taking the load of all of the floors above that point when it begins to accelerate in descent?

The exterior and core columns

When this section is skewing its footprint along the entire floor area

NOT!
The weight is almost all on the exterior and core columns.

as it tilts what must sustain that load in order to transfer it to the columns, and then to the ground?

Thru the core and perimeter columns below.

In a static state, the floor systems did several things; they A) carried the live and dead loads that were required for each individual floor B) they transferred these live and dead loads from everyday use to the core and perimeter columns C) and transferred lateral bracing between the core and perimeter columns.

Correct

In the dynamic state however this is not the case; the core has failed, remember? As the core is no longer able to carry its loads the hat truss at the top of the structure tries to transfer the weight to the perimeter columns,

Incorrect.
The hat truss was supported by the core and would be bearing down on the core.

and in turn they cannot handle these new loads so they begin to fail.

Sorry Charlie, no great amount of weight on the floor truss connections.

The building begins its descent and the first thing it meets is the floor system immediately beneath it,

Wrong again. almost all the weight is on the core and perimeter columns.

which now must not only hold its design loads, but also the weight of 15 other floors' worth of structure (north tower) or 29 other floors' worth of structure (south tower) respectively.

Nada

 

[tfk]

bill,

Hello Helloo

As you helpfully pointed out yourself, structural steel does not lend itself well to'springing' and of course the structure of a hollow box column exacerbates that deficiency to the point of impossibility in terms of a column springing out several hundred feet from the building.

For the rest your comments are purely subjective and a waste of space.

No, bill. YOUR silliness is pure, uneducated subjectivity. With an ulterior motive, of course.

I did some engineering, solved some stress vs. deflection and energy vs. deflection equations.

That is one of the differences between us. I CAN do these engineering analyses. You cannot.

tk

 

[twinstead]

I see you're still arguing as if you hold the majority opinion, Chris. Very nice.

 

[DGM]

The exterior and core columns

NOT!
The weight is almost all on the exterior and core columns.

Thru the core and perimeter columns below.

Correct

Incorrect.
The hat truss was supported by the core and would be bearing down on the core.

Sorry Charlie, no great amount of weight on the floor truss connections.

Wrong again. almost all the weight is on the core and perimeter columns.

Nada

Wow Chris:
Would you like to back up any of these assertions? (I hope you just retract because your wrong on so many levels) (and you know it)

 

[bill smith]

bill,



No, bill. YOUR silliness is pure, uneducated subjectivity. With an ulterior motive, of course.

I did some engineering, solved some stress vs. deflection and energy vs. deflection equations.

That is one of the differences between us. I CAN do these engineering analyses. You cannot.

tk

If you are going to continue to launch peronal attacks perhaps you had better be explicit with your 'ulterior motive' claim so that we can get everythng out up front. That way people can see whether there is any truth in your insinuations and i will have an opportunity to clear my name..

 

[tfk]

chris,

Please provide your evidence that anything CLOSE to this number of explosions were heard in ANY video, immediately before & during the collapse of the towers.

If the government would release the 7,000 video clips they are keeping from the public we could better assess all aspects of the collapses.

There are hundreds of videos WITH audio available from every possible angle on the internet. There is precisely ZERO way that those explosions could have occurred and NOT been picked up on the available videos.

Your contention that the answer is somehow obtained by a "vote" of the videos is nonsense. Any explosion associated with CD would be so overwhelmingly loud that, if the explosions occurred, they'll be heard on all of them taken from the approximately same location. If they did not occur, they'll be heard on none of them.

We have enough audio recordings available. It is incontestable. Explosions of the number and volume required for CD simply did NOT happen.

I am NOT interested in statements. I am interested in hearing this number of explosions for myself in any of the enormous number of videos that were produced that day.

You glibly discount all the witness statements about explosions and molten metal. That is just denial.

Not in the slightest. I am simply looking for OBJECTIVE evidence of when & how loud the alleged explosions were. Those are critical details that are FREQUENTLY glossed over, and sometimes mis-remembered, in the oral accounts.

I am also interested in HEARING (rather than your usual evading) an explanation of how those severed columns were magically absent in the debris pile at Ground Zero.

The vital evidence was removed and destroyed as fast as possible.

Nonsense. The hard, unequivocal evidence is available TODAY.

Here it is. Photos of Ground Zero.
http://911research.wtc7.net/wtc/evidence/photos/docs/ground_zero_aerialb.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/ground_zero_arial2_ort.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/us/us_wtc35.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/us/us_wtc36.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/us/us_wtc37.jpg


http://911research.wtc7.net/wtc/evidence/photos/docs/us/us_wtc43.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gs/p509.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gs/p508.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gs/p510.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gs/p515.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gzd_019.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gzd_043.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gzd_049.jpg
http://911research.wtc7.net/wtc/evidence/photos/docs/gzd_050.jpg


All told, there were approximately 10,400 individual columns above ground per tower.

Now, if 1/2 of all the beams in WTC towers needed to be severed to get the upper segment to fall at "free fall acceleration", then approximately 5,200 beams would still be 3 stories high, and 5200 3 story beams would have been turned into 15,600 1 story beams.

If the beams were blown by ANY method whatsoever, then the 1 story cut beams would outnumber the 3 story beams by a ratio of 15,600 to 5200. or 3 to 1.

If 1/3 of the beams were blown, then the 1 story cut beams would outnumber the 3 story beams by a ration of 1.5 to 1.

Please show me in these photos, this huge number of 1 story cut beams that far outnumber the 3 story assemblies that fractured at their bolted ends.

tom

 

[BenBurch]

Crown sheets. By not responding, you have accepted my argument? Then hydrocarbon (and wood) fires CAN soften steel to failure, and there is no longer any role for explosives or thermite or any conspiracy that does not involve getting those terrorists onto the planes.

 

[funk de fino]

funk,

We have been over this. Almost all of the load above the impact zone was on the core and exterior columns.

It would be physically impossible to put this load on the floor truss connections.

No, you are misepresenting what NIST say. The top section fell onto the bottom section when it hit the uppermost intact floor below it gave way due to overload. The intact florr could not take the dynamic load applied when the top section fell on it. The floors did not all have to hit square on at the same time like you have claimed

Even your mythical child could see this.

 

[funk de fino]

If the government would release the 7,000 video clips they are keeping from the public we could better assess all aspects of the collapses.

They are not.

NFPA (National Fire Protection Association) 921, which is the National Standard for Fire and Explosion Investigations, very clearly indicates in numerous sections that the possibility of explosives should have been thoroughly investigated. Specifically in NFPA 921 18.3.2 High Order Damage - “High-order damage is characterized by shattering of the structure, producing small, pulverized debris. Walls, roofs, and structural members are splintered or shattered, with the building completely demolished. Debris is thrown great distances, possibly hundreds of feet. High-order damage is the result of rapid rates of pressure rise.” World Trade Center’s 1, 2, and 7 all clearly met this definition; therefore they should have been thoroughly investigated and analyzed for explosives. Specifically, the use of “exotic accelerants” should have been investigated. In NFPA 921 19.2.4 -”Exotic Accelerants,” three indicators were clearly met that should have led to a thorough investigation in to the possible use of “exotic accelerants,” specifically as stated in the guideline, “Thermite mixtures.”

NFPA 9.3.6 covers Spoliation of Evidence. Specifically, 9.3.6.7 reads as follows: “Once evidence has been removed from the scene, it should be maintained and not be destroyed or altered until others who have a reasonable interest in the matter have been notified. Any destructive testing or destructive examination of the evidence that may be necessary should occur only after all reasonably known parties have been notified in advance and given the opportunity to participate in or observe the testing.”

Those are general guidelines for arson investigators. Not mandatory. Not anything NIST should have followed. Everyone could see what started the fires. You just start parroting other truther junk now?

 

[Grizzly Bear]

The exterior and core columns

NOT!
The weight is almost all on the exterior and core columns.

Are you forgetting already that the structure within the impact area has failed?

Incorrect.
The hat truss was supported by the core and would be bearing down on the core.

See above. When the core in the impact region fails, the loads from everything ABOVE that point are transferred to adjacent columns; in this case the only medium is through the hat truss, and out to the perimeter columns that are still intact. Now what happens when the columns located in and around the impact region are unable to sustain the new loads?

Sorry Charlie, no great amount of weight on the floor truss connections.

Wrong again. almost all the weight is on the core and perimeter columns.

Your goal post shift is one of the most bizarre claims I've ever come across with this controlled demolition conspiracy theory. I agree that the floors normally would never sustain such loads under ordinary circumstances, but under a dynamic collapse event you somehow believe that the loads are still perfectly in-line with their respective structural members?

When I look at videos of the collapse between both buildings I notice two variables; the cores in both WTC 2 and WTC 1 fail after the majority of the collapse for both structures has progressed to street level. Only then do they too collapse; this suggests to me a few things:

• The initiating failure in the core was primarily localized to the impact regions.
• The floor system on all levels, including the perimeter columns failed before the core columns did. This means that the floors exceeded their limits before loads were sufficiently transferred to the core during collapse.

In other words claiming "It would be physically impossible to put this load on the floor truss connections" comes across to me at least as just another red herring, and a false one on top of that. If they failed, then likelihoods are they sustained loads they were not designed for, simple as that and in the collapse this isn't surprising. You've never claimed this before since I've first started arguing against you, and I don't know why you're claiming this now.

 

[Architect]

I don't know when the top guys show up Bob. NIST just taking the report on the Twin Towers 'up to the point of collapse' should be enough to tell anybody there was a huge cover up. The NIST report on WTC7 is blown out of the water altogether.Is it true that NIST is now not trusted in the engineering community around the world ?

I was scanning back through some emails when I came across this, and -although I may well have missed it in the melee - it doesn't appear to have been addressed.

So, to answer the point, no - as far as I can tell the professional community sets considerable store by the NIST findings although there is some minor disagreement (Arup, Edinburgh University) about some aspects of the fire modelling. On that basis I have to ask where you formed this opinion and whether you can provide anything to back it up?

 

[Architect]

If you are going to continue to launch peronal attacks perhaps you had better be explicit with your 'ulterior motive' claim so that we can get everythng out up front. That way people can see whether there is any truth in your insinuations and i will have an opportunity to clear my name..

Bill, when I read this I am much minded of one of your earlier quotes:

Hi Bob....it's very revealing how hey melt away in the face of Super-Truthers. lol

I'd like to focus in particular on this melting away. You see, I've posed a series of questions of the two of you - in all fairness a lot of it is focussed at Bob, who seems to have done a bunk - and you've not responded to any of the substantive points.

I'll forgive Bob for not posting his space elevator work yet (presuambly there's patent and copyright issues with such sensitive work) but I'd really like to two of you to turn your attention to the fire performance issues we've highlighted back.

You've now got information of the actual characteristics of heated steel and, of course, the various standards and codes which recognise this problem. I assume, therefore, that you'll both be able to respond to the substantial problems they present to your own hypotheses.

 

[Furcifer]

OK, back to locomotive boilers.

If none of you truthers think that a hydrocarbon fire can weaken steel to the point of failure, why do oil burning steam locomotives explode when you allow the crown sheet to become dry? Why do you guys think that is, eh? Or are you going to go on record saying that a steam locomotive boiler is perfectly safe with a dry crown sheet if it is oil-fired?

And if you accept the fact that it will absolutely explode (unless the fusible plugs blow out, but nobody ever TRUSTS that safety mechanism) then how is that case different from the case that doomed those building and their trapped occupants?

Illuminate me, please?

But when you do, bear in mind that I know more about how steel works under such conditions than any of you appear to...

Wait wait, nobody trusts the fusible plugs? Geez, they sure as heck aren't teaching us that Ben. Doesn't anyone read ASME section VII in the real World?

I guess you don't have to bead the ends of the firetubes in the crown sheet either, according to bob there's no chance of the flanges getting weakened by the heat until they reach 4000F. Especially rolled and pierced tubes.

BOB: Where are the FMEA's you promised? How do these FMEA's differ from NCSTAR?