Are WTC collapse times of any value ?

[AlienSpaceBat]

After reading various threads about this, I calculated for myself the collapse times of the buildings including conservation of momentum (graphs & tables posted previously).

The collapse times they gave were 15.2 secs for a collapse initiated at the top of the building, and 9.7 secs for the top 30 floors falling as a block onto floor 80 onwards.

I don't know enough about the factors involved to be able to properly allow for air resistance, crushing of floors, destruction of concrete etc. I did decide to play a bit with the spreadsheet I made though.

Even allowing massive energy losses (50% of total energy at each floor collision), and even allowing for the floors to accelerate with 50% of the force of gravity, the total time elapsed in the case of the top 30 floors falling comes to 13.7 secs.




Don't get me wrong - I'm not saying that I think the buildings collapsed naturally. Its just that in the case of a failure at floor 30, even when allowing energy losses which seem far too large to me, the total collapse time still falls within the generally accepted values of 10 to 15 seconds.

I think that it might be better to focus on the other oddities of the collapses, rather than the supposed closeness of the times to free-fall.

Just wondered what anyone else thought of this ?

[LARED]

1. I think you need to take the information at face value

and rather than try and shove it under the rug, let it shine a little light.

[AlienSpaceBat]

2. I wasn't suggesting it be swept under the rug !

As I think you know.

I think there are plenty of oddities and potential smoking guns all around the events of 9/11.

I thought that the collapse times were one such, but now I'm not so sure, and I think that energies might be better expended looking at other aspects of what happened at the WTC on 9/11.

[LARED]

7. You were suggesting to ignore the holy grail of

free fall or near free fall dogma as proof of controlled demolition when you state, I think that it might be better to focus on the other oddities of the collapses, rather than the supposed closeness of the times to free-fall. If you remove the 'free fall evidence' for CD, what is left? No much.

Don't you see that doing this could be inciting heresy in the controlled demolition community. It sort of like saying lets ignore the Miracles of Jesus in attempting to understand His divinity.

I say welcome to the light of truth. Step out, bath in its glory you heretic.

[petgoat]

18. What is left?

The mushroom clouds of dust and debris.
The molten metal in the basement.
The reports of explosions by survivors.
The fact that the fires burned out.
The fact that the core went down when the lower core should have remained standing.
The fact that investigation was obstructed through withholding the blueprints,
restricting site access, and destroying the steel.
The straightening out of the tilting south tower block in violation of the law of
conservation of angular momentum.
The mysterious erosion of steel samples as reported by the WPI scientists in FEMA
Appendix C.
The failure of the NIST study to answer the above mystery.

There's tons of stuff left.

[AlienSpaceBat]

22. I also think there's plenty left

Just because I think that the collapse times don't definitively show a demolition took place, doesn't mean that everything that happened at WTC that day was as per the official theory.

It also, of course, doesn't mean that a demolition couldn't have taken place.

There are lots of reasons why the official story is suspect. If so much evidence wasn't being withheld I am convinced in my own mind that complicity to some degree is and would be provable.

[LARED]

24. Well not exactly tons in my view.

The mushroom clouds of dust and debris.

I've never seen mushroom clouds in controlled demolitions. Have you?

The molten metal in the basement.

I've never heard of molten metal in a controlled demolition. Have you?

The reports of explosions by survivors.

Naturally there are explosions in controlled demolition. It is also quite natural for witnesses to call the noise heard in a collapsing building explosions.

The fact that the fires burned out.

I saw fires right up to the collapse, didn't you?

The fact that the core went down when the lower core should have remained standing.

According to whom?

The fact that investigation was obstructed through withholding the blueprints,

Myth

restricting site access, and destroying the steel.

Myth

The straightening out of the tilting south tower block in violation of the law of
conservation of angular momentum.

Har, har. How does controlled demolition account for this notion of yours anyay?

The mysterious erosion of steel samples as reported by the WPI scientists in FEM
Appendix C. The failure of the NIST study to answer the above mystery.

Eutectic corrosion is not an indicator of controlled demolition.

[petgoat]

27. "not exactly tons in my view."

No, 'cause you're doing your damndest to look the other way.

I've never seen mushroom clouds in controlled demolitions.

The clouds of energetically ejected debris and dust are consistent with
the use of explosives. If explosives were used, the symmetrical straight-down
collapse indicates the demolition was controlled. The point is "were explosives
used?" not "does this look like every other controlled demolition I ever saw."

Van Romero said it looked just like a controlled demolition, and he's an expert.

As to molten metal, the same argument applies.

{it's} natural for witnesses to call the noise heard in a collapsing building explosions.

You're playing dumb, disinfo technique #9. Witnesses saw flashes of light from lower floors.
Firemen should know the difference between collapse noises and explosion noises. Rodriguez reported
an explosion before the plane even hit. So the basement was collapsing before the plane hit?

I saw fires

You're playing dumb again. The fires burned out. Brian Clarke walked down from the 84th floor
of WTC2 and didn't see any raging fires. The fact that he saw some flames is irrelevant.
Chief Palmer saw some fires on 78--small isolated fires he wanted to "knock down".

The assertion that site access eas restricted, that blueprints access was difficult and that
the steel was destroyed a myth.

Here are two ASCE documents referring to exactly those difficulties:

http://www.asce.org/pressroom/news/display_press.cfm?uid=1059

http://www.asce.org/pressroom/news/display_press.cfm?uid=1058

As to the steel, are you proposing that it was NOT destroyed?


As to the engular momentum of the tilting south tower, the CD theory AFAIK is that the only
way this could have been straightened out is by blowing the block to pieces in mid-air, which
appears to be what happened.


Eutectic corrosion is not an indicator of controlled demolition.

Straw Man. I never said it was. In this case it's an indication of a source of excess
sulfur or (perish the thought! Oxygen!) which source has not been identified and thus
still remains a mystery.

You are whistling very loudly past the graveyard.

[Make7]

3. Not for what they are generally used for around here, ...

... which is to "prove" that the collapses had to be caused by something other than the plane impacts, structural damage, and/or fires. Of course, to prove this would require someone to actually calculate the theoretical time it would take for a progressive collapse to be able to compare to the observed collapse times. The only other person I recall making a reasonable attempt at doing such a thing is Jim Hoffman. So let me take this opportunity to thank you for actually making the effort to do some calculations regarding this issue.

I would just like to add that although air resistance is a factor, I believe it is very probably negligible. Terminal velocity of a falling object is influenced greatly by the density of the material, and since the main structural elements of the buildings were relatively dense I don't believe they would be influenced, to any thing other than a very minimal degree, by the resistance of the air. (Don't quote me on that until I refresh my memory on how that all works.)

Your calculated times put a fairly large dent in one of the articles of faith of the controlled demolition proponents, it will be interesting to see what comments you will receive from them. (If any.)

:popcorn: Make7

[dailykoff]

4. Yes and no.

Structurally, no. There's no difference between ten seconds and ten days. The only way to have brought all that steel down was to blow it up.

Conceptually, yes. Everybody understands what free fall is and what it means, and they were close enough to free fall to truthfully use terms like "near free-fall speeds." I don't see how it would be possible to come up with more exact times anyway.

Just my two bits of course. :)

[Christophera]

5. Free Fall Collapse W/Steel Looks Totally Different, Blown Up Or Not

When steel collapses it mostly topples because only one load bearing element fails at once. When steel is blown up HUGE amounts of explosives are required (if shaped charges are not used) and that, in the case of reducing 1,300 foot steel columns to pieces so small they are not obvious in photos, looks like a series of BIG horizontal expansions at each level cutting the columns up.

What we see here is a massive explosion reflected upward originating at the center of the core.

[TheWraith]

6. And when did they repeal the law of gravitation?

"The only way to have brought all that steel down was to blow it up."

That's well beyond the range of misguided paranoia and into the realm of all-out fabrication. A building is a machine designed to keep itself upright. When it becomes damaged, it can collapse in any number of ways. To claim that explosion is the only way it could happen is equivalent to saying that the only way that an airplane could crash is if someone flew it directly into the ground, because if anything else happened it would just float in the air.

[Christophera]

10. Allow This:If It Were All Steel EXPL. The Only Way. This Looks Different!

The statment,

"The only way to have brought all that steel down was to blow it up."

is true, but the building wasn't all steel. If it was all steel and it was blown up, that would look totally different. A much larger explosion ejecting much more big, fast shrapnel from ripped and shredded steel members. Considering the towe rdidn't blow all at once, that series of explosons would throw descending rings of steel out at high velocities, higher speeds than that of the engine from flight 175. large single pieces of steel would have 500mph velocities at distances of 1 mile.

Cutting, demolishing, destroying steel with explosives requires HUGE overloading compared to destroying mineral based structures that are not as dense and fracture easily.

Consider also that an all steel tower with those proportions flexes and sways too much. So an all steel tower is not a possibility within engineering standards.

Here is what we see.



We have what is clearly mineral based material obscuring occasional structural steel (also occasionally ejected far outward) as the mineral based expands with great velocity to it's maximum radius.

A building is not a machine, it is a strcuture. Machines are made of various structures. When structures collapse they do it in very fixed ways according to their composition and design. Variations to collapse can be created intentionally, exlosives work well for this and is called demolition.

Free fall and total pulverization were events that happened. They really happened and they are VERY important and cannot be reasonably ignored or put aside. The fact that they happened within what is clamed to be a "collapse" deserves paranoic reactions.

Our government has been infiltrated and a secret portion controls.

[rman]

12. yeah well there was a lot of concrete in the floors

"So an all steel tower is not a possibility within engineering standards."

that's nonsense

[Christophera]

28. An All Steel Tower With WTC Proportions Won't Stand After 65 MPH Wind

Sure there are all steel towers, but you will notice they are not so tall and so narrow as the Twin Towers. Notice now that the new towers will have concrete cores.

Notice the total absence of steel core columns protruding from the top of the core.

[Make7]

31. RE: 65 MPH Wind

Christophera wrote:

An All Steel Tower With WTC Proportions Won't Stand After 65 MPH Wind

Could you post the calculations that the preceding statement is based on? Or the source from which you derived the information to reach such a conclusion? Or perhaps just a reasonably detailed explanation that would tend to support your statement?

-Make7

[Christophera]

32. Proportions And Flex Of steel Make Concrete A Common Engineering Choice

I cannot post such calculation. With common sense and a reasonably detailed explanation relating to some experience with the flex of steel, a supported conclusion from 3 directions is found.

1.Engineering logic and recognition of the flex of steel prohibiting steel in towers with the proportions of the WTC.
2.An unused design of concrete preserved historically.
3.Forensic evidence of photos showing no steel

From a historically supported engineering standpoint it explained why there was no steel and photos of the towers coming down show no steel. Steel will not stand and none is seen falling. Apparently there was no steel as it would not stand and photos do not show it.

Experience with the flex of steel structures, brings meaning to all that.

Recall, ......... the film of the steel bridge blowing wildly in the wind and falling.



Reasonably; the towers will not stand because:
The towers with their proportions would experience flying forces off the building faces in high winds. Yamasaki tested steel core tower models and they would fail from twisting at around 65 mph.

One of the concrete core designs considered was this, still believed to be the core by a uk web site.



It is a prestressed concrete core column. We know this didn't exist because there is no place for elevators and we know the elevators were in side the core. The reason it was not built is because Yamasaki had consulted with concrete specialists and none could find a method to cast the 1,300 foot prestressed core.

The towers exterior box columns bore 50% of the weight, the interior box columns 30% and the core 20%. The reason the exterior could take so much was thatit was dense with columns and they were held as ridgid planes by the concrete core. No deflection and deformations caused failures of shear wall effects.

All of what I've said regarding the need for a concrete core is reasonably consistent with the forensic photographic evidence of the wtc event which shows NO steel core columns whatsoever through this series.

[Make7]

45. RE: The 65mph figure

In Post#28 you said:

An All Steel Tower With WTC Proportions Won't Stand After 65 MPH Wind

Sure there are all steel towers, but you will notice they are not so tall and so narrow as the Twin Towers.

I responded requesting to see the calculations used to determine the 65mph figure. Or failing that, the source used showing the wind speed figure cited, or a reasonably detailed explanation of how you came to draw the conclusion in the first statement quoted above.

So, it seems that you are unable to do the calculations needed to arrive at a figure of 65mph. In that case, could you post the source where that figure is used? (Just saying they did tests is not adequate. I could claim that they did tests and the steel core design withstood winds of 140mph. Does that convince you? Why would you think that you stating tests were performed and they failed would convince anyone?) If you are unable to produce a source to support the 65mph statement, then it is no better than an unsubstantiated rumor at this point. (And one that appears to be factually incorrect.)

Using, as part of your explanation, your belief that the WTC towers were constructed with concrete-cores therefore making a steel-core WTC design impossible just isn't logical. You can either show that it was not possible for them to have steel-cores or you can't. Whatever was used as the final design is not relevant to providing the basis for concluding that the towers would not be possible with a steel-core design. (For example: my apartment building was not built using metal studs, but that in no way means that it is impossible to build an apartment building like mine using metal-stud construction.)

As for the second part of your quote, can you tell us why the Sears Tower is possible using a steel frame design, but the WTC was not? Exactly what is the difference in the proportions of the buildings that make one possible and the other not? Why has the flex of the steel in the Sears Tower not caused it to fail? (Or is that asking too much?)

-Make7

[AZCat]

46. The Citicorp Building is another good example.

LeMessieur had used an innovative steel frame design for the Citicorp building in Manhattan, but the structural contractor "value engineered" the welded connections for the frame into bolted connections, which severely weakened the structure (it was vulnerable to certain 70 mph winds). LeMessieur found this out (from a grad student IMHO) and organized a rush project to weld all the connections for the frame. Coming in at 57 stories it is shorter than the WTC but the frame certainly makes some structural compromises (there was a church that the team wanted to keep intact).

[Make7]

49. Although in relative terms,...

...I think it is not proportionally as narrow as the WTC towers or the Sears Tower. It is a fascinating example nonetheless. I read a great article concerning the wind issue regarding that building about six months ago, but I can't for the life of me find it now. Oh, well - I'm sure you've read enough on the subject already.

I am still interested in getting an explanation for how the WTC towers could not have remained standing in a 65mph wind with the steel frame that was used to build them. I hope Christophera comes through this time.

-Make7

[Christophera]

54. I Delivered Explanation-You Do Not Accept Evidence, Reason & Logic

Your post proves you do not accept evidence, reason or logic.

[piobair]

56. proclamation

What I don't accept are "Spock like" proclamations. What about the c4?

[Christophera]

57. TV Reference? Visit My Web Site, All Of The DEMO Details Are There

http://algoxy.com/psych/9-11scenario.html

Your television icon reference is lost no me. It would be changing the subject to ask you what "Spock like" is, so don't bother.

Show me the url of your web site espousing your beliefs of the nature of events on 9-11 since you are so passionate about this.

What do you hope to accomplish by dissing information that explains events?

[piobair]

58. website

I viewed your website and it is quite impressive in it's size and scope. Quantity,however, does not always correlate to quality. Your assumptions are based entirely on a documentary you say you saw but now it has been completely erased from all media. This requires a level of paranoia that I am not familiar with. I know you have been on a crusade to gather converts to the concrete core religion but your ability to deny all other evidence in favor of a nonexistant video is kind of strange. At some point common sense has to rear it's ugly head. As to the c4, it is pure conjecture and requires a Rube Goldberg complexity to carry out. 30 plus years of this secret with no one in the line of succession revealing it? Since this secret would have encompassed 6 different administrations, who is the keeper of the keys? Are we going to descend to a discussion of the Knights Templar or maybe the Illuminati? I am not qualified to comment on what might have happened but I do know unsubstantiated conjecture when I read it. I repeat, I am not qualified to put forth alternative theories...but niether are you. By the way,my expertise and education is in Fire Science and I get quite a chuckle out of some of the molten steel and Jet fuel can't melt steel comments. There are lots of unanswered questions re:9/11 but you don't have the answers.

[Make7]

66. Your explanation was inadequate.

No reason for the 65 mph figure was substantiated. How have you been able to determine that a steel frame building the size of one of the WTC towers would fail in a 65 mph wind?

For me to "accept evidence, reason or logic" in your answers, you must first provide some.

-Make7

[Christophera]

50. DISTORTION: It is Not My Belief That Makes A Steel Core Impossible, Logic.

Convienent demanding others do thinking for you, the "dumbed down" role.

Logic says,

IF this photo shows no structural steel and we know we are looking at the core, THEN the logic that steel flexes too much in the proportions of the WTC tower bears true as none is seen because it was not used in the core.



This one of many photos showing concrete where you say there was steel core columns. Bring your evidence showing the core you say stood.

[Make7]

52. This is what you wrote:

"An All Steel Tower With WTC Proportions Won't Stand After 65 MPH Wind

Sure there are all steel towers, but you will notice they are not so tall and so narrow as the Twin Towers."

All I am asking for is for you to actually provide some facts to support your statements. I cannot understand how anyone could possibly think that the WTC towers built with an all steel frame would suffer a structural failure in a 65 mph wind. I am not requesting that anyone think for me, I am asking for you to show that you have put some thought into your statements and are able to produce something that shows why you would believe this 65 mph figure that you cited.

Logic says,

if you can't back up your statements, they are not proven to be factually correct. Therefore, they amount to nothing more than your opinion.

-Make7

[Christophera]

59. Clearly You Have No Knowledge Of STRUCT. Steel & Cannot Recognize Facts

Fact: There are no core columns showing in this picture of the WTC 2 core.



If you cannot possibly understand how towers built with an all steel frame with the proportions of the WTC towers will suffer torsion, deformation and failure, you have no way to evaluate my information one way or another. Effectively an intellectual mute. For example: I ask, "why are there no steel core columns showing in the top photo?" and Make7 responds???????????????????????

[piobair]

60. required knowledge

It appears that you don't possess the required knowledge to understand what you expound upon either. I guess we are both ignorant of the circumstances but I'll just keep my ignorance to myself. What about the other questions I raised regarding how a secret of this magnitude could be kept through widely divergent administrations?

[Make7]

65. Are you able to show some reason for that 65 mph figure or not?

You said that "An All Steel Tower With WTC Proportions Won't Stand After 65 MPH Wind".

Can you show how you arrived at the 65 mph number? If you cannot, then I'm inclined to believe you are just making up facts to support your unproven concrete-core hypothesis.

I really don't understand why are you so reluctant to back up what you have said. It really shouldn't be a difficult thing to do.

-Make7

[piobair]

53. c4 coated re-bar

Christophera,

You spent a good deal of time a while back trying to convince everyone that the CD was accomplished by c4 coated re-bar that was built into the structures when they were erected. Where are you on this currently?

With all due respect to your memory, your inability to produce any evidence of the documentary you said you saw, renders that portion of your argument irrelevant.

[Christophera]

55. Tower Demise Had One Cause-Logic And Reason Dictate Explanation

The demise of the towers could have only been effected in one way. I have experience with high explosives, not demolition but this was a subject studied and the needed placement and distribution are fully appreciated for their value in creating an effect that appeared as the towers uniformly did on 9-11.

The word,

UNIFORM

wins my argument instantly. No two identical collapses in nearly identical structures could be caused by completely different collisions.

Currently, the analysis of the Twin Towers Demolition is burgeoning with evidence and veracity by comprehensively fitting the many seemingly unrelatable events of that morning, occupies a web site.

http://algoxy.com/psych/9-11scenario.html

With all due respect to your integrity as a human being or your ability to produce a decent and rational argument, 3,000 innocent Americans were killed and the official story DOES NOT explain free fall, total pulverization, uniform descents and a handful of other major inconsistencies; all this after failing to provide due process in a case of mass murder, a capitol crime, and destroying evidence.

What do you expect to accomplish by criticizing my information?

[rman]

34. So you're saying we've all been lied to for decades,

about the WTC towers being steel core/steel shell constructions.
(With lots of concrete in the floors that can account for the large amount of concrete dust.)
It's not like your story is the first i hear about the WTC construction.

There can be several reasons why no steel columns are showing in that picture.
- the part of the construction that's visible is very much obscured by dust and smoke
- whatever steel might have been protruding from the top can have broken off

That other picture which you often post does show something that does very much look like steel columns standing upright.

[Christophera]

44. In 1990 I Witnessed The Construction Video-The Truth, No Reason For A Lie

Posted by rman

So you're saying we've all been lied to for decades, about the WTC towers being steel core/steel shell constructions.
(With lots of concrete in the floors that can account for the large amount of concrete dust.)
It's not like your story is the first i hear about the WTC construction.

Not decades of lies, near 5 years for sure. The concrete in the floors was lightweight concrete and reacts differently to dispersal in the air with high explosives, it is also lighter in color. Here is an example.



The jet of darker particulate upward to the left is high strength structural concrete from the core while the billowing cloud front and center is lightweight concrete from floors. The dark particulate has large aggregate in it with mass that helps the dark jet gain upward velocity.

Below is an explosion ejecting particulate hundreds of feet near vertically up. That explosion centers on the core area.



Alignment can be seen in this photo.



Posted by rman

There can be several reasons why no steel columns are showing in that picture.
- the part of the construction that's visible is very much obscured by dust and smoke
- whatever steel might have been protruding from the top can have broken off

The problem with the above is that if the steel is not showing, it has been cut, the process of cutting so much steel so many times has the explosion looking completely different than the one we see above. Cutting steel with high explosive requires very heavy loads and is VERY visable, in this case huge horizontal blasts throwing pieces of steel near a mile to impact like that engine from flight 175 did.

Steel will not uniformly break off like that, some vertical members of 47 would be seen bent and leaning.

Posted by rman

That other picture which you often post does show something that does very much look like steel columns standing upright.

Below is the photo I post of a steel column. It is not a core column, it is an interior box column and it was fastened to the outside of the shear walls that formed the rectangular, steel reinforced concrete tube that comprised the core. This one, the spire, is identified by the stubs of floor beams protruding from them up higher and the floor beams silhouetted lower. Floor beams are a part of the outer tube of the “tube in a tube” construction.



Below is an overhead photo showing the interior box columns.



I have notated it to show how the interior box columns ring the core.

[dailykoff]

14. Sure, a building is a machine

and that's a useful metaphor. But it has its limitations. For instance, what kind of machine is it? A vehicle, like a plane or car? Not really, since it's stationary. An engine? Not really, since its purpose is not to convert energy into motion or do any other kind of mechanical work, apart from heating, cooling, and circulating occupants.

A better metaphor is a tree, because a) it's stationary and sustained by circulation systems, and b) a steel-frame skyscraper is essentially a solid structure composed of smaller cells, like a tree trunk, and it would have to sustain a heck of a lot more damage than a single chop to experience total disintegration.

In other words there wasn't enough damage to produce the destruction we saw on 9/11.



Note the redunancy of the central core structure particularly.

[dailykoff]

15. Or to put it another way:

The damage we did see on 9/11 could only have been produced by high-powered explosives, not by plane crashes and subsequent fires.

[hack89]

16. What if an internationally respected foreign fire safety company

not only accepted without question that fires could have caused the collapse of the WTC but actually proposed a collapse mechanism? Would that raise even the slightest doubt in your mind? Do you have the professional and academic credential to question them?

In ambient design the column has a particular buckling mode
based on an effective length between each floor.
In a multiple floor fire scenario that buckling mode can
be changed.

The columns are initially pushed out as the floors expand in
response to the fires. As the floors increase in length and
buckle as a result of expansion they provide less support to
the columns.

In addition the floor stiffness decreases as a result of material
degradation. There is then potential for the external columns to
buckle over their increased length.

As the fire floors buckle and provide less support to the
columns, the columns look for this support from the cold floors
immediately above and below the fire floors.

The cold floors in turn become over loaded and buckle,
resulting in a mechanism that could propagate and could lead
to collapse of the whole structure.

http://www.arup.com/fire/feature.cfm?pageid=6267

[dailykoff]

17. Yes, it raises doubts in my mind

about the Arup firm. The paragraphs you quoted are pure science fiction. And guess what? Their website shows that Arup runs an engineering "consulting" business (as in, "we tell our clients what they pay us to tell them") with ties to Swiss Re, the reinsurers who for some unknown reason asked no questions about three unprecedented and highly unusual losses.


http://www.arup.com/ourwork.cfm?pageid=5834

[Name removed]

19. Deleted message

Message removed by moderator. Click here to review the message board rules.

[dailykoff]

26. What facts?

There are no facts in the quoted paragraphs, only speculation bearing little relation to the structure of the Trade Center towers or any other building.

And as far as I can tell the report makes no specific structural recommendations based on the WTC collapses other than to call for improved evacuation procedures.

[hack89]

29. OK n/t

[AlienSpaceBat]

20. Here we are again

What Arup said is being misstated. They conducted some studies and modelling to try to find generalised possible collapse mechanisms for tall buildings.

we considered it essential to develop a clear understanding of possible structural collapse modes in severe fires.
We therefore commenced a major program of numerical analysis of the response of tall building structural forms to multiple floor fires.

They didn't say that they had established a collapse mechanism for the WTC towers. They specifically called out NIST on their scenario, and showed an example of a possible mechanism that showed NIST to be wrong.

To be fair all round - Arup did say that there were scenarios that could cause tall buildings to collapse by fire, but they also said that NIST's hypothesis was specifically wrong.

Its just misleading to keep saying that Arup are validating NIST, making 2 organisations in agreement. It isn't so.

[hack89]

21. Who mention NIST? - it is time to move on.

Arup's study will show that fires were reason enough to cause the collapse of the WTC. They believe that fires caused the collapse. No mention of any other possible mechanism.

Did Arup prove NIST wrong? I didn't think so. Why aren't you willing to wait until all the studies are completed? We can then compare them to the studies being done by 9/11 "researchers" and everything will be clearer.

[AlienSpaceBat]

23. I don't see that that is what they are saying

They are saying that there are generalised scenarios that could cause a collapse of tall buildings. They are not saying that their example is what actually happened - they are giving it as a counter-example in their criticism of NIST.

That's why its not right to say that Arup have agreed with any particular mechanism for the WTC collapses.

[hack89]

38. Lets step back a bit...

and address a more basic issue. The constant refrain of the 9/11 community is how it is "impossible" for the WTC towers to fall with out demolition. Both NIST and Arup present mechanism as to how they could have fallen without demolition. The public comments to the NIST report from various professional organizations in general support this basic premise.

My question to you is a simple one: In light of the fact that the fire safety engineering community does not question that fires could have brought down the towers, are you willing to concede that it is at least theoretically possible for the WTC towers to fall without demolition?

[AlienSpaceBat]

41. Simple answer

Yes. I think that it would be possible for fires to cause a collapse, given the cases that Arup have modelled.

I have to add a caveat in that I haven't investigated this with any thoroughness, so I don't think its stronger than 'this is my impression at the moment'.

I don't think that the scenarios of building collapse by fire apply to what happened at the WTC though. I also have a problem in that the cases as I understand them would not destroy the core structure.

[hack89]

42. Thanks for your honest and straightforward answer. nt

[petgoat]

25. NIST said the floors buckled the columns by pulling them inward,

and even provides photographs that they claim proves it.

Arup proposed that the columns buckled outward.

Too bad they recycled the steel so fast, and wouldn't let
people take photographs, huh?

[Christophera]

30. Definition Of Machine & Yes, Not Enough Damage For Disintegration

I've bolded the definiton of machine that might fit the events at the WTC but the towers were structures like a tree.


ma·chine
n.
A device consisting of fixed and moving parts that modifies mechanical energy and transmits it in a more useful form.
A simple device, such as a lever, a pulley, or an inclined plane, that alters the magnitude or direction, or both, of an applied force; a simple machine.
A system or device for doing work, as an automobile or a jackhammer, together with its power source and auxiliary equipment.
A system or device, such as a computer, that performs or assists in the performance of a human task: The machine is down.
An intricate natural system or organism, such as the human body.
A person who acts in a rigid, mechanical, or unconscious manner.
An organized group of people whose members are or appear to be under the control of one or more leaders: a political machine.
A device used to produce a stage effect, especially a mechanical means of lowering an actor onto the stage.
A literary device used to produce an effect, especially the introduction of a supernatural being to resolve a plot.
An answering machine: Leave a message on my machine if I'm not home.

The overhead photo shows the interior box columns ringing the core. THe vertical steel elements inside are not core columns, they are too small. They are elevator guide rails. The trussed corners are is the crane platform which fastened to the inside of the outer steel frame work.

[AlienSpaceBat]

8. It is truthful to speak of near free fall speeds

But when I take the case of the south tower which has a plainly seen block of 30 floors that starts to pivot and fall, it looks like the mass of that block will inevitably cause something near to a free fall collapse, just by itself.

I think that although the collapse was near free fall, it doesn't mean what I originally thought it meant.

As a result, I am thinking that it may be better not to focus on collapse times so much as to look at
e.g.
how the top 30 floors could rotate without cutting charges on the core
the vertical ejection of material upwards as christophera points out, which *looks* counter-intuitive
the collapse mechanism
the energy of expansion of the dust cloud
the lateral energy of ejected debris
squibs and ejected dust
etc

In the interests of full disclosure I'll post the data tables up as soon as I've made some gifs of them. They're a bit dry, so to speak (!), but I would be interested in informed comments as I am by no means claiming that I am 100% right here.

[menschmaam]

9. Faster than Freefall

I have spent a lot of time looking at collapse footage.
I highly recommend 911 Eyewitness.

It appears that the fall is actually faster than freefall, if one counts the horizontal momentum, and or the upward momentum involved before DOWN becomes the dominant direction.

If the only direction were down, the speed would be slightly slower than freefall, but the ejecta is being forcibly propelled before gravity takes over.
The forces are sucking the dust that used to be a building to the ground.
http://thewebfairy.com/911/glow
shows the dustclouds being sucked inward, rather than expelled outward as would be expected in a typical controlled demolition.

Also, in a typical controlled demolition, a spire of steel would not turn to dust and blow off sideways.

The Strange Collapse of the Spire
http://www.plaguepuppy.net/public_html/spire/The%20Strange%20Collapse%20of%20the%20Spire.htm
http://tinyurl.com/2moxw

[Christophera]

11. Excellent Point & Logic. Add Distances Up To Down And Divide By Time

Consider that throughout the demolition there was upwardly cascading material, this doubles the distances travelled, or more depending on how far up it goes.



Far faster than freefall. Excellent point! Thank you.

[rman]

40. WTC7 sure seems to fall at free-fall speed in vacuum,

according to what's presented in 911 Eyewitness.

It's unusual for a controlled demo, it's even more unusual for a 'natural' collapse.

[LARED]

43. See link for correct fall times of WTC 7

http://wtc.nist.gov/pubs/WTC%20Part%20IIC%20-%20WTC%207%20Collapse%20Final.pdf

Page 28.

[Christophera]

47. ERRORS: Wrong Page & Cannot Resolve Question With Questionable Source

That page does not provide correct fall times.

Using NIST, who's information is VERY much in question, to resolve a question, is not reasonable without testing the information.

[LARED]

48. Thank you, its' page 26 not 28

to resolve a question, is not reasonable without testing the information.

So tell me do you hold yourself to the same standand?

[Christophera]

51. Of Course: OK, 9.0 S. For 7's Fall.Observe The Source Of This Information.

The source of the above information is photographic, just as what was used to gather the fall rates of WTC 7 NIST prepared. The above source however shows the concrete core of WTC 2. It must be concrete because structural steel simply cannot have that appearance.

The source of the above photo has passed the test. It is genuine. The interpretation of the photo is logical and consistent with the photo and common knowledge in the engineering world.

The NIST information of page 26 passed its first consistency test. 2.5 seconds just is not enough difference between that and faster rates calculated.

[rman]

64. WTC7 fell 100meters in 4.5 seconds (image heavy)

And your solid concrete core in that photo might just as well be a bundle of steel beams with a lot of smoke and dust obscuring much of it.

Here's the remnants of the core of WTC1 near the end of the collapse.

screenshots from 911eyewitness video http://www.911eyewitness.com/

[AlienSpaceBat]

13. Here is the data I used ...

If anyone has any comments or corrections I'd be interested.

Collapse of top 30 floors, conserving momentum, no energy losses

Collapse of top 30 floors, conserving momentum, 50% of energy lost at each floor collision, gravity 50% acceleration

[dailykoff]

33. Really thorough and impressive!

Here are the conclusions I'd draw:

1) The high speeds of the collapses don't necessarily prove anything beyond the fact that the perpetrators were interested in the fastest possible demolitions, were highly skilled, and had access to all the resources the job required.

2) The collapses themselves, however, prove that explosives were used to demolish the buildings, at least in my view.

3) The "near free-fall" speeds remain very helpful indicators to those just beginning to grasp the situation that the buildings didn't collapse as a result of plane crashes or fires.

[LARED]

35. Your conclusions have some holes.

1) The high speeds of the collapses don't necessarily prove anything beyond the fact that the perpetrators were interested in the fastest possible demolitions, were highly skilled, and had access to all the resources the job required.

Actually if free fall is the bench mark the collapses were not high speed. they were quite slow. Something like 50 percent slower based on the calculations presented. Neither free-fall or the slower speeds proves anything, although the seemingly close match between the observed times and 50% of available energy used to attain the observed fall time does point away from controlled demolition and towards a 'natural collapse.

2) The collapses themselves, however, prove that explosives were used to demolish the buildings, at least in my view.

Perhaps you could expand your view to explain how you believe this is proved.

3) The "near free-fall" speeds remain very helpful indicators to those just beginning to grasp the situation that the buildings didn't collapse as a result of plane crashes or fires.

50% or more over the free fall speed is not 'near free fall.' I do agree that promoting this false notion is helpful in helping the more scientifically gullible to fall for CT hokum.

[dailykoff]

36. Please. A quarter mile in 10 seconds is "quite slow"?

Tell that to the next cop who pulls you over.

[LARED]

37. Commendable attempt

at shopistry. Please try again

[Ferry Fey]

61. Commendable attempt

at rhetorical flourish, but I believe you meant "sophistry."

[LARED]

62. Why yes I did

That's what I get for not using spell check.

[Make7]

63. Thankfully, sometimes a helpful DU member will catch spelling mistakes..

..with an accuracy Microsoft is still hoping to achieve. There are rumors that the computer giant is trying to implement a World Wide Web Human Spellcheck, although project HuSpellWeb™ has been denied by corporate headquarters. When questioned at a recent stockholders meeting, Microsoft chairman Bill Gates replied, "We have people watching the Web all the time." Immediately after delivering his response, he broke into a disturbingly sinister laugh... It has been reported that he was seen compulsively rubbing his hands together as he left the meeting shortly thereafter.

-Make7

[hack89]

39. Look up "absolute" and "relative"

it will make things clearer.