That’s why they did it. It throws off suspicion.
Suuuuure, crashing planes into tall building is not suspicious at all. :rolleyes:
Structural (albeit Mechanical, not Civil) Engineer checking in. Same theories and equations, different applications.
Take a look at the graph link Valgard provided. To elaborate, the most important quantity to consider is buckling, which is given as:
Pcrit=cEI/L[sup]2[/sup]
where Pcrit is the compression load at which a column will buckle, c is a constant based on how the column is supported at each end, E is the elastic modulus (aka Young’s modulus) of the column material, I is the area moment of interia of the column (a function of the cross sectional geometry), and L is the length of the column between the supports.
The driving quantities here are E and L. Note in the link that as E drops, so does Pcrit by the same percentage. So, if the column gets hot enough to where E has dropped 50%, we likewise end up with a 50% decrease in the buckling load. IIRC*, this, combined the fact that there were fewer columns to hold up that part of the building, is how the first tower collapsed.
IIRC* for the second tower, we had another failure mechanism going on. Note in the linked graph that yield strength decreases with temperature too. This behavior applies to yield tensile and shear, and ultimate tensile and shear strengths. Because of increased temperatures and loss of other supporting structures, the rivets holding up at least one of the floors failed in shear. When this happened, the length of the column between supports doubled. Taking a look at the buckling equation, we note that a doubling of the column length results in a 75% decrease in the buckling load, i.e. Pcrit is only 1/4 of what it was originally, and this doesn’t even take the heat into account. Buckling failure occured soon after.
I don’t think Johnny’s friend is going to get it either; I mainly posted to provide more details to Johnny LA and anyone else interested. Also, it’s not that often that I can answer a question or elaborate on an answer in GQ without someone having beaten me to it.
*I remember the failure mechanisms well, I’m just kind of hazy as to the order of the building failures.
But you suspect the wrong people. Not the actual masterminds. The fact that it does not make sense to you just goes to show how powerful and manipulative these people are.
Right. See, they could come up with a plausible cover story. But a plausible cover story would be too suspicious. So they come up with a ridiculous cover story, which makes people suspect a conspiracy. And once that happens, these shadowy figures have got away clean!
On second thought, they don’t have to make up cover stories at all. After all, they control everything already. They don’t HAVE to bother lying to us, they just do it for FUN.
At the risk of being written off to tinfoil land …
What about WTC buildings 6 & 7? Forget the towers for a minute. Seems plain enough to me what destroyed them. But other buildings were destroyed that day … and apparently not by planes.
http://www.prisonplanet.com/011704wtc7.html
I know this is GQ not GD, but for Christ’s sake why is this thread still active?! There are mountains of evidence proving beyond any reasonable doubt that we know exactly how & why the Twin Towers were destroyed.
This is the crux of the problem. No skyscraper could ever, EVER, be made to “fall like a tree”, i.e. to angle over while retaining its tall vertical shape.
Although a tall building, the WTC in particular, looks like a huge solid object that could just be “pushed” at the very tip by some imaginary giant and slowly creak over, it can not happen. The moment that any tall structure goes a little beyond its designed center of gravity it instantaneously loses all strutural integrity and ceases to be a building and instead becomes a massive, unsupported pile of steel. Which falls straight down. If you watch close-up footage of the first tower falling you’ll see that after the top half began to topple over a little it then just collapsed.
There is nothing really unique (or man-made) about the ‘look’ of a controlled demolition, the implosion into nothing. It is totally natural. Gravity works in straight lines.
As for the OP’s friend saying that to him, I wouldn’t have even bothered debating it. I would have laughed at him. He might has well have suggested that extraterrastrials did it as revenge for Roswell! 
You’re not in tin-foil hat territory there, just in random-link-with-lots-of-speculation land. Nothing in that article makes me think the explosives theory is any more credible, and much of the language makes it clear the author doesn’t know what he’s talking about.
Well I used that link because it seemed a little better than the first few Google results. Here are a couple more from some out-there personal websites …
http://killtown.911review.org/wtc7.html
http://www.whatreallyhappened.com/fema_report.html
Hardly serious sources … BUT they have the video feeds and photo sequences. The second link even goes into some detail of the construction of the building. I first saw this stuff in a book by Disinfo Press called “Everything You Know Is Wrong”. From all of the photos/videos it seems fairly obvious that WTC #7 did NOT collapse due to fire damage or debris. If it did, it is apparently the first building of its kind to collapse due to fire. The previously posted article was the first I’ve seen with an apparent acknowledgment that officials could have authorized the demolition. Honestly that idea seems a little off to me because I figure (shot in the dark here) that it would take some time and preparation to set a building up for demolition. Not something they could decide to do one (very chaotic) morning if the wrong circumstances arise. Leading me back to my tinfoil hat … Someone must have set something up, at least in that one building.
That ‘Killtown’ link provides all the information needed to see that WTC7 would indeed have suffered major damage. It directly faced WTC1 (much higher than WTC6 in between), and so would have taken major impacts from debris from that collapse. It was higher than any other buildings directly facing the twin towers, and so it seems reasonable that it would have suffered a different pattern of damage - potentially a greater one. Plus, that page is full of other speculative gibberish.
Both of the above linked sites just reinforce my point. They keep going on and on about how the collapse looks “eerily similar” to a “controlled demolition”. This is ridiculously ignorant. There is no reason they would look different!
I didn’t bother reading thru much of either of them, but do they mention the idea that the foundation of WTC 7 was also damaged by the tremors produced by the collapses of 1 & 2?
Dude…even I have a degree in structural engineering.
No, because they were not knocked over by the impact of the jet. The WTC was built like a bundle of straws. IIRC, the outer wall consisted of a bunch of metal tubes that held up the concrete floors by a bunch of pins and trusses while the floors prevent the tubes from buckling outward. By punching a big hole in the outer wall and setting a giant ass fire, the crash does two things:
- reduces the number of vertical structural members
- weakens the structure providing lateral support against buckling
So what happened was not that the planes knocked that shit over, but created a scenario where the connecting members failed, the outer support walls buckeled outward causing each floor dropping on the floor below like a collapsing house of cards.
Your friend, not knowing anything about how structures work, probably doesn’t believe you because in his mind, the entire thing should have toppled over like some ho getting punched by Mike Tyson.
I’m not sure, because we were arguing over the basic issue, that he doesn’t think they should have toppled over like that. I think what he thinks is that the upper storeys on the side of the towers that were hit should have fallen sideways if the vertical girders had failed. That is, imagine building a tower at the beach. You carve away at one side of it, and the top topples over to the side. My contention was that the horizontal joists failed because they were weakened by the fires, so the towers could do no other than to fall inward.
So I don’t think he thinks that the upper storeys should have been knocked over, but that he thinks they should have fallen over when the verticals failed. He contends that since they didn’t, then it must have been interior demo charges.
You guys are helping a lot to bolster my side of the argument, and I thank you. I’m going to wait for him to present his case though. I’ll be sure to report what he sends.
Maybe I missed it somewhere Johnny but does your friend have any particular background in any of the following areas?
- Demolitions.
- Effects of heat on materials.
- Structural engineering.
- Strength of materials.
If he doesn’t (and it doesn’t sound like he does) then he’s just guessing and going on what he’s heard from some random schmoe on the internet, and we all know how reliable that is 
As far as why the whole thing didn’t tip over like a log, you can also thank the P-delta effect. The bending moment (torque) at the base of a column which is supporting a load (P) is zero so long as the column stays vertical. As soon as the top of the column starts to move out to the side by some amount (delta), the bending moment jumps (P times delta). Those additional bending moments act to deform the column even farther, delta increases, moment increases some more…
Beams and columns were destroyed. The load paths changed, unbraced column lengths go way up and so the buckling load drops (per Strainger). Things start to tilt, just a tiny bit, and it doesn’t take long for the massive load (upper 10 floors or so) times the small deflection to result in massive moments being applied to the remaining columns which then break, dropping the whole mess almost straight down. That enormous impact load takes out the next floor and the progressive collapse continues right down to the street.
As to why it didn’t look more like a sandcastle, keep in mind that a sandcastle is made of pretty tightly compacted grains of sand. There’s not a lot of empty space so when things fail they have to move outwards, that’s the only place that there’s any room. An office building on the other hand has loads of empty space - in the case of massive structural failure there is plenty of room for the building to just squish down flat in the volume that it already occupies.
A better analogy is to think of standing on an empty beer can. As long as the weight is evenly distributed, it supports you. As soon as someone comes along and pings the side, it crushes. That’s basically what happened.
This is absolutely correct!
In fact if you got a close up perspective on the collapse there probably was some horizontal movement during it. But it is quickly overcome by gravity and pulled downward. When viewed from far away it’s going to appear like a straight down collapse if the chunk of building moved 15 yards to the right and then thousands of yards straight down.
You can’t even use the analogy of a tree in this situation either. A tree has both compressive and tensile strength, in other words it holds together if you push on both ends or pull on both ends. A building only has compressive strength.
A tree (or log) laid on it’s side can be used to span a gap and retain it’s strength.
If you tried to lay a skyskraper on it’s side to bridge a gap it would just fall apart.
My friend has sent his first “evidence”. The (very short) “article” has a couple of links to Systems Planning Corporation, which shows their remote control panels. It also contains a link to a page where a French guy posts his theories about the attacks.
The page lists such theories as these:
[ul][li]LIHOP (Let It Happen On Purpose). Deliberated stand-down of the aerial defense.[/li][li]HIHOP (Help It Happen On Purpose). Falsely failed anti-hijacking war drill, with electronic final control of planes.[/li][li]MIHOP 3 (Make It Happen On Purpose). Hijack totally done by electronical means (Eric Bart’s theory).[/ul][/li]Hm. No “THAACT (Terrorists Hijack Aircraft And Crash Them). Hijack carried out by dedicated members of terrorist organisation with no malfeasance on the part of the government.” :dubious:
The author also says, “There was definitely, I think, a shaped charge in the attacking plane. The DU penetrator hypothesis seems more and more probable to me.” Regarding the Pentagon he says, "This attacked was very carefully engineered, which in itself is a “conspiracy smoking gun”.
I plan to point out to my friend that the control systems he read about “require several remote CTS units”. Thus, modifications would have to be carried out by a team that would have had to replace the regular maintenance personnel, and the none of the pilots and other people who inspect the aircraft would have to overlook the extra components on an aircraft they are intimately familar with.
Since the French page is the work of one guy with a conspiracy theory, whose qualifications are unknown, I can’t accept it as a legitimate cite. I mean, he says that since the attack on the Pentagon was carefully engineered, it must have involved a conspiracy of government officials! :rolleyes:
I’m looking forward to your input, especially from engineers who can back up my claim (or, for that matter, disprove it – although I think that’s very unlikely) that remote control systems would not be able to be put into aircraft without detection.
C’mon, you KNOW they would have used one of those “undetectable” remote controls – everything invisible under the panels. They first thisng the crew would notice would be the plane making a turn on its own. :rolleyes:
Where would you put a DU penetrator on the plane? The nose cone covers the avionics, radar, etc. You’d need those for a remote control system, plus there’s the nightmare of haing to reqire everything. Modern aircraft have literally hundreds of miles of wiring in them, and splicing in complicated electronics would be no easy task.
But why would you need the DU penetrator when it’s a well known fact that a tornado can drive a straw through a tree at about the same speeds the planes crashed into the WTC?
by thinking of the idea of such an act, to cause as much widespread damage and panic as possible, you can almost negate the chances of a theory involving explosives to bring down the building. in cases where demolitions explosives are used to bring down buildings; the goal is to localize the rubble and to control the debris as much as possible. if there were a group trying to accomplish the bringing down of the wtc in any form of a mass destruction plot. why not try to topple them over to cause as much damage as possible instead of a controlled blast which is designed in a surgical manner. seems completely aginst the warfare tactics of a group of that sort to begin with. how i see it, from the shoes of the ones who would have done it, what would their goals be? maximum yeild? ever play jenga?