9/11 media happenings

[WouldBe]

Crap! As shown by the wikipedia quote 'essentially hollow tubes around a massive central core' and which says that the core took the majority of the weight (and could take all of it).

And I'm thoroughly bored of your waffle!

That pic you posted proposing to show a thermite cut cental column is also a hollow 'tube'. Admittedly quite a thich hollow 'tube' but still a hollow 'tube'.

 

[Crispy]

That pic you posted proposing to show a thermite cut cental column is also a hollow 'tube'. Admittedly quite a thich hollow 'tube' but still a hollow 'tube'.

No, that's a column alright. Welded steel plate.

 

[Crispy]

Outside columns - comparitively weak

Central core - VERY VERY STRONG

Can we quantify this? I mean, it would be nice to run an independant structural analysis, even a simple one.

 

[TheArchitect]

[LOL] Oh Jazz, you're not making sense here.

1. What was supporting the outer edge of the floor slabs?

2. Are you seriously suggesting that the floors cantilevered from the core?

3. What is the cross-sectional area of the perimetric outer steelwork compared to the inner core steelwork?

4. How do you believe that the wind loadings on the external steelwork were redistributed?

5. Why have you STILL not responded to survival of parts of the core for 15-20 seconds following the main collapse?

6. Likewise you have failed to address the damaged caused to the core by the aircraft impacts.

7. And again, you have failed to recognise the damage caused to the core by collapsing elements of the surrounding fabric.

I put it to you once again, Jazz, that you are a fraud. You are deliberately misrepresenting and ignoring facts in order to suit your own predetermined POV. Two key planks of your case having dissolved (free fall and extent of fires) you are clinging to this one issue in a desperate attempt to retain a vestige of an argument.

 

[WouldBe]

No, that's a column alright. Welded steel plate.

It's still hollow.

 

[Crispy]

It's still hollow.

Yes, you would never make a solid one.

 

[beesonthewhatnow]

Jazz - quick question.

Do you still believe missiles were fired from the planes, in addition to CD, or were they brought down solely by CD?

 

[TheArchitect]

Debunking Jazz's Absurd Structural Theories

Yamasaki and engineers John Skilling and Les Robertson worked closely, and the relationship between the towers’ design and structure is clear. Faced with the difficulties of building to unprecedented heights, the engineers employed an innovative structural model: a rigid "hollow tube" of closely spaced steel columns with floor trusses extending across to a central core. The columns, finished with a silver-colored aluminum alloy, were 18 3/4" wide and set only 22" apart, making the towers appear from afar to have no windows at all.

Also unique to the engineering design were its core and elevator system. The twin towers were the first supertall buildings designed without any masonry. Worried that the intense air pressure created by the buildings’ high speed elevators might buckle conventional shafts, engineers designed a solution using a drywall system fixed to the reinforced steel core. For the elevators, to serve 110 stories with a traditional configuration would have required half the area of the lower stories be used for shaftways. Otis Elevators developed an express and local system, whereby passengers would change at "sky lobbies" on the 44th and 78th floors, halving the number of shaftways.

(Taken from www.skyscraper.org)

The structural system, deriving from the I.B.M. Building in Seattle, is impressively simple. The 208-foot wide facade is, in effect, a prefabricated steel lattice, with columns on 39-inch centers acting as wind bracing to resist all overturning forces; the central core takes only the gravity loads of the building. A very light, economical structure results by keeping the wind bracing in the most efficient place, the outside surface of the building, thus not transferring the forces through the floor membrane to the core, as in most curtain-wall structures. Office spaces will have no interior columns. In the upper floors there is as much as 40,000 square feet of office space per floor. The floor construction is of prefabricated trussed steel, only 33 inches in depth, that spans the full 60 feet to the core, and also acts as a diaphragm to stiffen the outside wall against lateral buckling forces from wind-load pressures."

Taken from www.greatbuildings.com

The structural integrity of the World Trade Center depends on the closely spaced columns around the perimeter. Lightweight steel trusses span between the central elevator core and the perimeter columns on each floor. These trusses support the concrete slab of each floor and tie the perimeter columns to the core, preventing the columns from buckling outwards.

Tim Wilkinson, Lecturer in Civil Engineering, University of Sydney

The tubular framing system for the perimeter walls resisted all of the lateral forces imposed by wind and earthquake, as well as the impact loads imposed on September 11. Although we had used closely spaced columns in an earlier building, it was Minoru Yamasaki who proposed that we use narrow windows in the WTC towers to give people a sense of security as they looked down from on high. Our contribution was to make the closely spaced columns the fundamental lateral-force-resisting system for the two towers. The tubular framing system also precluded the need for the customary 30-foot column spacing in interior areas, making column-free, rentable space structurally desirable.

In support of Yamasaki’s design, during the construction, before the windows were installed, I noticed that people felt comfortable walking up to the outside wall, placing their hands on the columns to either side, and enjoying the wonderful view. If the wind was blowing toward them, they would walk right up to the outside wall; however, if they felt even a trace of pressure from a breeze from behind, they would at least hesitate before walking to within five feet of the wall . . . and many would not approach the wall at all.

Another structural innovation was the outrigger space frame, which structurally linked the outside wall to the services core. This system performed several functions. First, gravity-induced vertical deformations between the columns of the services core and the columns of the outside wall were made equal at the top of the building; at other levels, the differential deformations were ameliorated. Second, wind-induced overturning moments were resisted in part by the columns of the services core, thus providing additional lateral stiffness. Finally, the weight of, and the wind-induced overturning moment from the rooftop antenna (440 feet tall) was distributed to all columns in the building . . . adding additional redundancy and toughness to the design.

Reflections on the World Trade Center , Leslie E. Robertson

The structure of the towers was a new system made of three main elements: (a) an exterior steel tube with closely spaced column to carry gravity and lateral load, (b) interior steel core columns and beams to carry gravity only and; (c) the light weight concrete on steel deck floors
supported on simply supported steel truss joists.

Professor, Department of Civil and Environmental Engineering
University of California

Now, tell us: did you JUST look at the Wiki article or did you actually bother to do any real research Jazz?

 

[TheArchitect]

And I'm thoroughly bored of your waffle!

Thoroughly beaten, more like. Damn those pesky twins facts and research!

 

[beesonthewhatnow]

So, in other words, the core was designed to resist only the gravity loads of the building, not the lateral ones.

Which there was a fuckload of the moment the floors gave way.

So the core collapsed.

Have I got that right TheArchitect?

 

[TheArchitect]

So, in other words, the core was designed to resist only the gravity loads of the building, not the lateral ones.

Which there was a fuckload of the moment the floors gave way.

So the core collapsed.

Have I got that right TheArchitect?

Well, it would have played a part in resisting the overturning moment (that's a structural term, Jazz) but essentially, yes.



ETA: It's really just "Architect", but someone had already pinched the name. The added "The" seems awfully pretentious, in retrospect.

 

[Jazzz]

Can we quantify this? I mean, it would be nice to run an independant structural analysis, even a simple one.

Have another look at the columns in question - you can see the outside ones comprising the shell. Compare them to the ones in the centre!

And if they can take lateral loads, then they must be able to stand for themselves. And if they can stand up for themselves, then a central core column certainly can, for it makes the outside look puny! And if a central core column certainly can * then 47 interconnected central core columns over a large footprint is hardly going to flop over.

You might be reassured that structures like this seem to stand up without too many problems.

* alliteration unintended

 

[beesonthewhatnow]

Cool, really does seem rather simple. TBH I'm amazed the towers lasted as long as they did afer impact.

 

[TheArchitect]

Jazz

You seem to be encountering some difficulties in answering these, which are rather critical to any assessment of the loadbearing system at WTC.

1. What was supporting the outer edge of the floor slabs?

2. Are you seriously suggesting that the floors cantilevered from the core?

3. What is the cross-sectional area of the perimetric outer steelwork compared to the inner core steelwork?

4. How do you believe that the wind loadings on the external steelwork were redistributed?

5. Why have you STILL not responded to survival of parts of the core for 15-20 seconds following the main collapse?

6. Likewise you have failed to address the damaged caused to the core by the aircraft impacts.

7. And again, you have failed to recognise the damage caused to the core by collapsing elements of the surrounding fabric.

I do look forward to your detailed response.

 

[WouldBe]

You might be reassured that structures like this seem to stand up without too many problems.

Height?
Weight?
Construction method?

 

[beesonthewhatnow]

then they must be able to stand for themselves. And if they can stand up for themselves, then a central core column certainly can, for it makes the outside look puny!

Unless I've missed a massive point here, surely the whole building depended on them both acting together - remove one part, you fuck up the other.

Hardly complicated is it?

 

[WouldBe]

Have another look at the columns in question - you can see the outside ones comprising the shell. Compare them to the ones in the centre!

As I asked before

How many outer columns?
How many central columns?

 

[WouldBe]

Unless I've missed a massive point here, surely the whole building depended on them both acting together - remove one part, you fuck up the other.

Hardly complicated is it?

In Jazzz world you can take one of the side rails off a ladder and it still works.

 

[Jazzz]

So, in other words, the core was designed to resist only the gravity loads of the building, not the lateral ones.

Which there was a fuckload of the moment the floors gave way.

So the core collapsed.

Have I got that right TheArchitect?

Absolutely nonsense because

1) The central core was simply fantastically strong. It was the floors that weren't designed to carry the lateral loads. This allowed them to be very light.

2) No explanation is there for these 'lateral loads' suddenly appearing, especially as the floors wouldn't be able to transmit any once they pancake!

 

[TheArchitect]

Still awaiting your response to this Jazz: sure you have it in hand, eh?

[sigh]

Where to begin.

1. You will recall that I asked you for more specific evidence or details of the material you claim had been ejected such distances. This has not (yet) been forthcoming, so in the interim I'm going to assume that you mean larger elements and not the minor ejecta we see comming through the windows.

2. Well firstly, we know that the individual steel beams did not weigh "hundreds of tons". In actual fact core columns were no longer than around 30ft/10m, and the facade sections smaller. Similarly the floors rested on lightweight trusses.

3. Secondly, there is no evidence that the core columns were ever found substantially outside the immediate area of the buildings, likewise the floor trusses broke into sections, hence you must be talking about the facade.

4. Next, we need to differentiate between the lightweight aluminium cladding - which was the same profile as the steel, of course - and the actual structural work. There is every reason to believe that dislidged lightweight cladding would travel a considerable distance.

5. Now let's look at the collapse mechanism. Following the loss of the internal floor trusses, the external structural envelope buckles so much that we can see it. Obviously this will be placing the steelwork under considerable stress. Then the joints fail. Now we know that steel is, in fact, actually quite elastic (or else springs wouldn't work, eh?) and indeed you confirm that yourself in another post. So there is every reason to assume that when these loads are released, there will be a degree of movement.

6. However this is not the only potential means by which movement might occur. Most obviously, sections of facade moving downwards would hit lower work and - shock - be deflected (ie bounce) outwards. If an object has already fallen a hundred or two hundred metres, then it's going to be moving at a fair rate.

7. Similarly (and I have to say I don't hugely buy this one myself, but throw it in for completeness) once the floors collapsed, the facade was unrestrained. Given the staggered joints it is perfectly possible that some sections would have swung out by a few metres prior to collapse, which combined with several hundred metres of air resistance could easily translate into a larger horizontal movement.

Just to back all this up, I'm going to quote another source:

<snip>


Now it seems to me that these all rather explain the potential mechanism in a bit more detail than your own "how did it go that far" argument, and if you plan to rebutt it it would be quite reasonable for us to expect to see something quite detailed.

I shall, as ever, await your response with interest.

 

[editor]

You might be reassured that structures like this seem to stand up without too many problems.

Err, maybe that's because it's just 134 feet high, 3m wide at the base and just 15 centimetres at the top.

In other words this tiny little spike bears absolutely no relevance whatsoever to the WTC. None. You may as well compare it with the Skylon. Or a tree.

http://www.irish-architecture.com/buildings_ireland/dublin/northcity/oconnell_street/spire.html

 

[TheArchitect]

Absolutely nonsense because

1) The central core was simply fantastically strong. It was the floors that weren't designed to carry the lateral loads. This allowed them to be very light.

2) No explanation is there for these 'lateral loads' suddenly appearing, especially as the floors wouldn't be able to transmit any once they pancake!

[sighs, again]

Jazz

You appear to have a problem assessing evidence in a competent manner.

The only "proof" you have for your theory is the Wiki piece - and for all we know, you could have edited that yourself. On the other hand I've presented you with a series of detailed quotes including some from the designers of the towers which directly contradict your own position.

Now who am I going to believe?

Similarly you have failed to address any of the technical points put to you. Why is this? Just to make life easy for you, here they are (again):

1. What was supporting the outer edge of the floor slabs?

2. Are you seriously suggesting that the floors cantilevered from the core?

3. What is the cross-sectional area of the perimetric outer steelwork compared to the inner core steelwork?

4. How do you believe that the wind loadings on the external steelwork were redistributed?

5. Why have you STILL not responded to survival of parts of the core for 15-20 seconds following the main collapse?

6. Likewise you have failed to address the damaged caused to the core by the aircraft impacts.

7. And again, you have failed to recognise the damage caused to the core by collapsing elements of the surrounding fabric.

 

[Jazzz]

Jazz

You seem to be encountering some difficulties in answering these, which are rather critical to any assessment of the loadbearing system at WTC.



I do look forward to your detailed response.

I thought I said I'm bored of you, you pompous fool. You can shove your huge lists, long C&Ps, demands for 'detailed responses', and smart-arsed quotations up your elevator shaft!

 

[beesonthewhatnow]

2) No explanation is there for these 'lateral loads' suddenly appearing, especially as the floors wouldn't be able to transmit any once they pancake!

Errr, do you not think that the floors collapsing might have been pushing against the core just a teensy weesy bit?

 

[TheArchitect]

I thought I said I'm bored of you, you pompous fool. You can shove your huge lists, long C&Ps, demands for 'detailed responses', and smart-arsed quotations up your elevator shaft! :

Can I take it that you conceed defeat?

Or would you like me to remind you of your misrepresentations, half truths, and lies again?




ETA: on second thoughts, let's update the list anyway. It'll save scrolling back later.

You have thus far been proven wrong on 5 (yup, 5) key areas of your argument:

1. Fire Engineering. You claimed that they produced a damning account of the NIST report, and implied that this undermined the entire investigation. However you failed to place the FE quotes in context, and when we did it it became clear that they had a number of very specific areas of concern, primarily relating to co-ordination of the firefighting effort and the installation of the original fire protection.

2. Destruction of Evidence. You claimed that NIST had deliberately destroyed or at the very least supressed important evidence. However when pressed, the only item you can identify is the supposed evidence of thermite/ate to the steelwork.

3. Intensity of Fires. You claimed that the fires were minor, based on a single report from the 78th floor - despite the fact that the main impact and fires were around 80 to 81, which was immediately clear from photgraphic evidence. You then claimed that the fires were going out immediately prior to the collapse. This was again proven wrong.

4. Free Fall. You have claimed (repeatedly) that the towers fell at near free fall speed, and that the resistance offered by the lower structure would have slowed the collapse significantly. Yet we know that free fall time for a 471m structure would be around 9.22 seconds, and most CT accounts of the collapse put actual time at between 12 and 15 seconds. This is a difference of between around 30 and 60%, which is considerable.

5. Structural System. You claimed that the core would have been self supporting following collapse. When challenged to provide evidence and detail, all you could manage was a single Wiki piece. In turn, I quoted a series of sources including - wait for it - the structural engineer who designed the tower. All proved you wrong.

I can't help but notice a running theme here, Jazz. It seems to involve you misrepresenting evidence and then getting caught.

 

[beesonthewhatnow]

I thought I said I'm bored of you, you pompous fool. You can shove your huge lists, long C&Ps, demands for 'detailed responses', and smart-arsed quotations up your elevator shaft!

Huge lists and C&Ps of facts from people qualified in the subject, and thus rather important, no?

 

[Crispy]

huge lists,
long C&Ps
smart-arsed quotations

That's called fucking sources

 

[TheArchitect]

Jazz seems to be having a little difficulty with the concept of "evidence" and a strange insistence on our part to actually analyse his rather rough and ready hypotheses regarding the collapse.

Still, at this rate he''ll either conceed defeat or lose on every single topic within a day or two.

Jazz: Are you really up to this, or are you going to storm off in the huff again?

 

[tarannau]

I thought I said I'm bored of you, you pompous fool. You can shove your huge lists, long C&Ps, demands for 'detailed responses', and smart-arsed quotations up your elevator shaft!

I suspect you would call any architect pompous once they demolished your ill-thought out theory.

Are you going to concede that the designers of the WTC may be able to comment more authoritatively than the unnamed authors of a Wikipedia entry.

I've rarely seen such an embarrassing lack of knowledge and deliberate evasiveness on a thread. Your only answer seems to be to keep referring to the aforementioned Wikipedia article and make boneheaded assertions.

Cripes. Poor old Jazzz makes a big fool of himself. Again. This is actually worse than the Huntley and Pentawater mistakes...

 

[Jazzz]

1. Fire Engineering. You claimed that they produced a damning account of the NIST report, and implied that this undermined the entire investigation. However you failed to place the FE quotes in context, and when we did it it became clear that they had a number of very specific areas of concern, primarily relating to co-ordination of the firefighting effort and the installation of the original fire protection.

Dear god, I can't believe I'm bothering with this. I quoted the fire engineering piece to show that the investigation was a shambles, and without the work of a proper investigation, any theories of collapse would remain hypothetical. NOT that they were saying the towers were demolished. It's you who kept trying to turn my words into something else and you continue to do so now.

2. Destruction of Evidence. You claimed that NIST had deliberately destroyed or at the very least supressed important evidence. However when pressed, the only item you can identify is the supposed evidence of thermite/ate to the steelwork.

OH MY GOD you are repeating this again! How many times times do I have to say that it's not up to me to list what they chucked away! Fire Engineering didn't have to in order to complain that they were chucking all the evidence away! You idiot!

3. Intensity of Fires. You claimed that the fires were minor, based on a single report from the 78th floor - despite the fact that the main impact and fires were around 80 to 81, which was immediately clear from photgraphic evidence. You then claimed that the fires were going out immediately prior to the collapse. This was again proven wrong.

The photographic evidence betrays absolutely no evidence of any 'inferno' in either tower and shows that there was no smoke cloud generated by the South Tower before it collapsed.

4. Free Fall. You have claimed (repeatedly) that the towers fell at near free fall speed, and that the resistance offered by the lower structure would have slowed the collapse significantly. Yet we know that free fall time for a 471m structure would be around 9.22 seconds, and most CT accounts of the collapse put actual time at between 12 and 15 seconds. This is a difference of between around 30 and 60%, which is considerable.

blah blah blah, we've been over that, I've explained that it does not represent considerable resistance. You of course try to turn that into that I'm saying it constitutes proof of a CD in itself which I never have - I just state that it is easily explained by a CD theory.

5. Structural System. You claimed that the core would have been self supporting following collapse. When challenged to provide evidence and detail, all you could manage was a single Wiki piece. In turn, I quoted a series of sources including - wait for it - the structural engineer who designed the tower. All proved you wrong.

None proved me wrong! You are having a laugh again, or just think that by C&P a load of stuff you have somehow showed something! In fact they all said exactly the same.

That you made the extraordinary assertion that the 'massively strong' central core could not stand on its 47 fantastically thick steel columns has utterly convinced me that my appreciation of the mechanics is far, far better than yours.

'and when we did it it became clear that they had a number of very specific areas of concern'

AMAZING... the first poster I have ever encountered to use the Royal 'we', and utterly without irony!