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Shaking a 275-ton Building

Zonk posted more than 7 years ago | from the without-using-your-superpowers dept.

Supercomputing 110

Roland Piquepaille writes "If you want to predict how a tall building can resist to an earthquake, some researchers have better tools than others. Engineers from the San Diego Supercomputer Center (SDSC) have built a full-size 275-ton building and really shaken it to obtain earthshaking images. The building was equipped with some 600 sensors and filmed as the shake table simulated the 1994 Northridge earthquake in Los Angeles, California. It gave so much data to the engineers to analyze that they needed a supercomputer to help them. Now they hope their study will yield to better structure performance for future buildings in case of earthquakes."

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Somebody saw this coming (3, Informative)

MichaelSmith (789609) | more than 7 years ago | (#18728753)

The page you are looking for has moved. Please go to the main EurekAlert! homepage to locate the section you are interested in and reset your bookmarks.

If you are looking for this week's current news releases, click on "Breaking News" once you reach the main EurekAlert! homepage. If you are a reporter looking for the embargoed news section, go to the main EurekAlert! homepage, log in with your username and password and then, from the main reporter homepage, click on "Embargoed News." If you are a PIO looking to submit a release, go to the main EurekAlert! homepage, log in with your username and password and then, from the main PIO homepage, click "Submit a Release."

Thank you. Please contact the webmaster of the refering page to report the bad link. Thank you.

Re:Somebody saw this coming (0)

Anonymous Coward | more than 7 years ago | (#18728773)

Roly only copies and pastes anyhow. Probably not worth reading...

Re:Somebody saw this coming (5, Informative)

zentagonist (944342) | more than 7 years ago | (#18728777)

http://www.eurekalert.org/pub_releases/2007-04/uoc --ei041107.php [eurekalert.org] should be the article ... no images though.

Re:Somebody saw this coming (0)

Anonymous Coward | more than 7 years ago | (#18731871)

http://www.eurekalert.org/images/ [eurekalert.org]

may contain what you're looking for :)

http://visservices.sdsc.edu/projects/nees/article. php [sdsc.edu]

is better though

free porn [zataka.com]

Re:Somebody saw this coming (1)

Kwiik (655591) | more than 7 years ago | (#18728803)

Thanks for the awesome and quick mirror, +5++ karma 2u

Re:Somebody saw this coming (0)

Anonymous Coward | more than 7 years ago | (#18728811)

This has got to be the fastest Slashdot effect in history. The page was unavailable even before the article was posted!

Wow (5, Funny)

hack slash (1064002) | more than 7 years ago | (#18728759)

The simulated quake must've been so big it shook the images off the linked page!

Any structural engineers around? (2, Insightful)

QuantumG (50515) | more than 7 years ago | (#18728763)

Are we at the point in history where we can design a building completely inside a computer and simulate the effect earthquakes of various degrees will have on the building?

Who makes that software?

How much does it cost?

Re:Any structural engineers around? (2, Interesting)

Arclight17 (812976) | more than 7 years ago | (#18728899)

I imagine that the software is custom written.
But it wouldn't surprise me if there were a market for such a thing... Include some other foreseeable disasters (fire, flood, airplane, Michael Jackson...), and sell it to major construction companies in skyscraper or other 'secure' building markets.

And just for kicks, maybe add an easter egg like sim city, so that you can destroy your buildings with aliens, dragons, etc. :-D

Re:Any structural engineers around? (4, Informative)

Tomfrh (719891) | more than 7 years ago | (#18728945)

Are we at the point in history where we can design a building completely inside a computer and simulate the effect earthquakes of various degrees will have on the building?

Pretty much.

Who makes that software?

People like this: http://www.csiberkeley.com/ [csiberkeley.com] http://www.risatech.com/ [risatech.com] .

How much does it cost?

About $5000.

The only problem is (4, Insightful)

Moraelin (679338) | more than 7 years ago | (#18729097)

Technically, yes. The only problem is, any simulation is only as good as the model it uses. E.g., you can also simulate scattering of alpha particles through a foil, but if you based it on the old raising pie atom model, you'd get the awfully wrong results anyway.

Hence what these guys are doing: a good old fashioned experiment, involving an actual building on a giant table that shakes, reproducing the exact movements recorded in an actual earthquake. That's how you find out if your model and simulation are actually the right ones. If the building behaves like in the assumed models, then all's well, if not, well, someone will have to come up with a better model.

It might seem that wth, we already know the laws of mechanics well enough, we don't need experiments to test them. The problem is that any model is based on some simplifications, since you just don't have the computing power to even account for all waves, reflections and interferences in a big building with hundreds of joints and thousands of metal bars, pipes, whatever other discontinuities through the walls. So physicists get to decide what are the important parts to simulate, and which should at best be lost in the decimals.

E.g., if you want to know if a horse floats, you can just as well imagine it to be a sphere or a cube. (As the wisecrack goes, "you know you're an engineering student if you approximate a horse as a sphere, because it makes the math easier.") Actually, wisecrack aside, for that you won't even imagine it to have any shape at all, since shape is irrelevant. It doesn't really matter what exact shape it is, just the mass and the volume. E.g., if you want to know how fast a rocket reaches the moon, you don't need to know the exact shape or colour of the rocket, you can just think it's a point. Etc.

That's how we solve problems nowadays. We get to decide what is really important, and what can be safely ignored in the model.

Unfortunately, if you to be really sure that you did the right choices, you have to compare it to what happens in real life. Does your simulation really behave like the real thing in that situation? Or did your approximating the horse as a sphere lead you to a wrong solution like rolling it along the race track to win?

That's, in a nutshell, what these guys did.

Re:The only problem is (2, Interesting)

AJWM (19027) | more than 7 years ago | (#18729141)

E.g., if you want to know how fast a rocket reaches the moon, you don't need to know the exact shape or colour of the rocket

True enough for moon rockets, but for some simulations -- like projecting whether a given asteroid (1950 DA [nasa.gov] for example), the colour does matter if you're project the orbit to see if it hits Earth in 800 or so years. Over such long time intervals the difference in sunlight pressure (and a couple of related effects) on a light vs dark surface will affect the trajectory.

The same effects have an affect on the rocket too, of course, but as you point out, on that scale they're not important.

Re:The only problem is (2, Informative)

Moraelin (679338) | more than 7 years ago | (#18729843)

Very much so. Each problem has a different set of details that matter and details which can be safely ignored. And a different need for accuracy.

Re:The only problem is (1)

jimicus (737525) | more than 7 years ago | (#18729281)

It might seem that wth, we already know the laws of mechanics well enough, we don't need experiments to test them.

I would point out that every major race in the whole of history has been pretty much convinced that they already knew all the important stuff.

Aristotle, for instance, also argued that you didn't need to do experiments. And look how spectacularly accurate his models of how an object travels through the air are.

Very much so, yes (1)

Moraelin (679338) | more than 7 years ago | (#18729811)

Very much so, yes. Excellent example of why models need to be tested, in fact.

Re:The only problem is (1)

DerekLyons (302214) | more than 7 years ago | (#18729817)

It might seem that wth, we already know the laws of mechanics well enough, we don't need experiments to test them. The problem is that any model is based on some simplifications, since you just don't have the computing power to even account for all waves, reflections and interferences in a big building with hundreds of joints and thousands of metal bars, pipes, whatever other discontinuities through the walls. So physicists get to decide what are the important parts to simulate, and which should at best be lost in the decimals.

This test was pretty simplified too - as what was tested was really a model of a real building. (a honkin' big model, granted, but a model none the less.) All the pipes, walls, elevator shafts, stairwells, etc... found in a real building are noticeable by their absence.

Spherical horses (2, Funny)

gr8dude (832945) | more than 7 years ago | (#18729913)

Here's the long version:

There was a very wealthy gentleman who wanted a scientific method to be able to predict the outcome of any horse race. He asked a geneticist, a statistician and a physicist to look at the problem and promised each a million dollars if they could find a solution.

After a year of study the gentleman asks the scientists what they have come up with.

The geneticist says, "Well, we have looked at parentage, gentic composition, hormone levels, musculature and sexual activity of all the horses raced last year, and we could find no pattern amongst the winners.." The statistician says, "We looked at the history of each and every race. We compared times, owners, ages, parentage, and many other variables. We could find no pattern."

The physicist says, "We calculated the solution from first principles, and here it is!" He hands a huge sheaf of papers to the wealthy gentleman. The gentleman responds by returning a million dollars in cash to the physicist.

"Well done!" he cries, "But how did you do it?"

"Well remember," says the physicist, "it only works for a spherical horse moving in a vacuum...."

Re:The only problem is (3, Insightful)

cluckshot (658931) | more than 7 years ago | (#18734551)

Since my father was one of the team that sent men to the moon. I know a bit more about simulation and testing than the average bird. On Redstone Arsenal (near Huntsville, Alabama) stands a building where they did full mock up shake testing of the Saturn V rocket. I appreciate the intent of people who wish to do full computer simulations. These are getting very good and they delete with the need for many simple tests. Nothing substitutes for the real thing and doing real tests. This was a 37 story rocket they were launching.

The remark about decimal points is valid. Everyone forgets that the only math that truly exists is integer math. We enjoy using approximations using floating point math but that is all that these are. They are approximations. The list of errors that arises out of these approximations is long. This math only operates well within about 3 decimal places and then it begins to develop progressive errors.

In Apollo mission computer programming there was a decision made not to attempt over 5 decimal places in navigation and simply to do correction measurement over time. It worked like a charm. It was possible to calculate much more finely but in reality the measurements were not more valuable. Nothing was to be gained by the determination of 11 decimal places that the mission required for accuracy.

Shaking a 275 ton building will hold as a good approximation for that size range but will not do too well in estimation of a 275,000,000 ton building. It will require actual measuring of such a building. There are many such approximations that come up that people do not consider. For example the velocity of the top of a building is different than the bottom. In really big buildings level and plumb have to bend for the earth. In really big buildings what is the pull of the tide? All sorts of things like that begin to have significant value

Shaking Building Not New (3, Interesting)

goombah99 (560566) | more than 7 years ago | (#18729253)

Miliken Library at caltech which was an ten story building built before 1980 had a huge eccentric weighted rotor on it's roof which every year the engineering school would Activate and drive the building into resonance. All the book shelves inside were cross braced to withstand the effect. It's still there.

Link that works...for now. (3, Insightful)

djupedal (584558) | more than 7 years ago | (#18728775)

Read more... [supercomputingonline.com]

"Wednesday, Apr 11 @ 13:13 PDT The powerful earthquake struck suddenly, shaking the seven-story building so hard it bent, cracked and swayed in response. But this was no ordinary earthquake. In a groundbreaking series of tests, engineering researchers from UC San Diego's Jacobs School of Engineering jarred a full-size 275-ton building erected on a shake table, duplicating ground motions recorded during the January 17, 1994 Northridge earthquake in Los Angeles, California. To record the impact on the building, the structure was fitted with some 600 sensors and filmed as the shake table simulated the earthquake, yielding a flood of data including stress, strain, and acceleration -- so much information that engineers were having a hard time making sense of it all. That's where visualization experts from the San Diego Supercomputer Center (SDSC) at UC San Diego came in. "

good for Godzilla prep (1)

ystar (898731) | more than 7 years ago | (#18728831)

so could you reconstruct downtown Tokyo with a beowulf cluster of these buildings?

Here's the Correct Link (4, Informative)

AaxelB (1034884) | more than 7 years ago | (#18728781)

Link! [eurekalert.org]

Two little dashes in the url became one superdash!

Re:Here's the Correct Link (0)

Anonymous Coward | more than 7 years ago | (#18730379)

Someone needs to stop writing their articles in MS Word

What they really did... (4, Funny)

Anonymous Coward | more than 7 years ago | (#18728791)

They threw a truly awesome kegger and cranked the amps to 11!

Think harder (5, Funny)

GFree (853379) | more than 7 years ago | (#18728795)

It gave so much data to the engineers to analyze that they needed a supercomputer to help them


Why are they using a supercomputer?

Screw that, let's wait for Earthquakes@home - and hope the name doesn't scare off some people.

Re:Think harder (0)

Anonymous Coward | more than 7 years ago | (#18730403)

'cause no one wants to wait for the latency involved with distributed computing when we've got 3 large installation IBMs on the floor with a queue time of only a day or two.

Re:Think harder (1)

KORfan (524397) | more than 7 years ago | (#18731001)

Maybe someone will design an earthquake-proof brick.

Shakey (3, Interesting)

Tablizer (95088) | more than 7 years ago | (#18728833)

The building where I used to work and write bad software every work day used to be owned by a military contractor and was built to withstand a nuclear blast. It is no longer owned by the military contractor, but is still used by non-mil gov't agencies who want communications to remain up after emergencies (floods, fires, quakes, riots, nukes, etc.) They put their servers and communications centers there. I was told that they used to do periodic "shake tests" on it by hooking up huge cranes to each edge and vigorously shaking it for a while. It seems that would be risky because it would weaken it. Even though shaking it in tests might not topple it, it may introduce undetected fractures that may result in problems on the next earthquake or whatnot. Perhaps its infrastructure is purposely built for easy inspection, being what it was originally designed for.

Re:Shakey (2, Interesting)

Anonymous Coward | more than 7 years ago | (#18729199)

What you describe is a good application for eccentric mass vibrators, if you can affix one to the structure. I do appreciate the scale of the shake table these folks built, but sometimes you can't move the structure to your shake table to test it.

Eccentric mass vibrators are just like the cell phone vibrator (or other things you know of that vibrate) but much larger. And you strap these to the roofs of large buildings, wherever they are.

This is a crude Wikipedia article on it: http://en.wikipedia.org/wiki/Vibrator_(mechanical) [wikipedia.org]

Here's a good example of one at UCLA: http://nees.ucla.edu/eccentric_mass.htm [ucla.edu] .

Another interesting way to do structural testing is called snapback testing. A lot like when you played tug-of-war with your friend, but you let go of the rope. So you attach cabling to a structure and force it to be bent by pulling really hard on it. The coupling mechanism allows for rapid de-coupling of the force being applied (i.e., it lets go). The structure snaps back to its original position, and in so doing you can analyze its dynamic behavior under roughly controlled conditions.

Re:Shakey (2)

iMac Were (911261) | more than 7 years ago | (#18729675)

I saw the words "vibrator" and "srap on". I'm going to need a cold shower I think.

Re:Shakey (0)

Anonymous Coward | more than 7 years ago | (#18733085)

I am glad you caught my intimation...

Re:Shakey (1)

Tablizer (95088) | more than 7 years ago | (#18733897)

Another interesting way to do structural testing is called snapback testing. A lot like when you played tug-of-war with your friend, but you let go of the rope. So you attach cabling to a structure and force it to be bent by pulling really hard on it. The coupling mechanism allows for rapid de-coupling of the force being applied (i.e., it lets go). The structure snaps back to its original position, and in so doing you can analyze its dynamic behavior under roughly controlled conditions.

Don't use ACME snapbacks, otherwise the building flies away with a "poing!" sound.
     

HD videos of the shake (4, Informative)

Bo'Bob'O (95398) | more than 7 years ago | (#18728867)

A coworker of mine is in the department, and showed me this page: http://visservices.sdsc.edu/projects/nees/article. php [sdsc.edu]

It has a video of the shake as well as high def video of the simulations themselves. It's pretty damn cool, you can watch the whole building flex and sway about on top of the the shake table, and the waves propagate through the building. (Each colored dot is a GPS sensor, 10 per floor, over 7 floors).

Picture LInk (2, Interesting)

Pinky3 (22411) | more than 7 years ago | (#18728871)

Link [ucsd.edu] to UCSD news release with pictures.

Re:Picture LInk (1)

holywarrior21c (933929) | more than 7 years ago | (#18730305)

parent should have been modded informative for that....the subject is already interesting

Too bad (2, Funny)

Anonymous Coward | more than 7 years ago | (#18728883)

It's too bad noone can find a way to protect steel frame buildings from collapsing due to fire...

Oh. Wait.

Re:Too bad (1)

QuantumG (50515) | more than 7 years ago | (#18729047)

That's the absolute best kind of conspiracy theory. Make a claim so stupid that no professional engineer would ever bother to come forward and refute it.

Let me try to make a parrallel to computing, as there's probably more software engineers here than there are structural engineers.

Say the so called "digital Pearl Harbor" that has been widely speculated about was to happen. Maybe someone hacks into a power plant and shuts down the power to a hospital and a few thousand people die or something. The world is shocked. CNN have their mood music turned up high and are saying how evil chinese hackers did this, etc, etc.

Someone wants to cast doubt on these assumptions so they claim that no power plant in the history of power plants has ever failed due to a computer attack.

People who are naive of computer security hear this claim and say "man, you're right!" Throw in a few more easily confirmable claims and a few unconfirmable claims and you've got yourself a nice conspiracy theory.

Meanwhile, all the software engineers are sitting there going "they connected a power plant up to the internet? What a bunch of idiots."

Much like all the structural engineers are sitting there, right now, going "yeah, of course if you fly a jet plane into a building it is going to fall down."

Power plants are not something you should connect to an untrusted network.. they're not designed to be secure in that kind of environment.

Buildings are not something you should fly planes into.. they're not designed to keep standing up under that kind of stress.

I also recommend the South Park episode where Cartman accuses Kyle of causing 9/11.. it's quality.

Re:Too bad (1)

ikekrull (59661) | more than 7 years ago | (#18729069)

The twin towers had as one of their design parameters the ability to resist the impact of aircraft. To say skyscrapers are not designed to resist aircraft impact shows your ignorance, not the original posters.

Re:Too bad (1)

sp3d2orbit (81173) | more than 7 years ago | (#18729123)

Bill Clinton couldn't get blown without the world finding out.

Ignorance is thinking the next president could blow up the WTC without anyone finding out.

Re:Too bad (1)

Hognoxious (631665) | more than 7 years ago | (#18729709)

Alone he couldn't find his way to the bathroom. But that's exactly what the Zionazisraeluminatis want you to believe, as they sit in secret manipulating events from their hidden base in Atlantis. In other news, the Jews sank the Titanic.

Re:Too bad (1)

AJWM (19027) | more than 7 years ago | (#18729229)

Much like all the structural engineers are sitting there, right now, going "yeah, of course if you fly a jet plane into a building it is going to fall down."

Uh, no, not necessarily. If it were just the jet flying into the building, it would have fallen at the time of impact. They didn't, it was an hour or so later. The fires (from the jet fuel) had to weaken the structural steel first. The Empire State Building survived a hit from an airliner (admittedly not a jet, so lower speed impact) early in its history, and it's still standing, because there was no fire. (And perhaps because the steelwork is more of a self-reinforcing grid rather than the outer shell/core plus bridge-like floor trusses of the WTC towers. Once the beams weakened enough to tear away from the edge supports (outer wall and elevator core) there was nothing else to hold them up -- and the impact of that floor on the floor beneath ripped that one loose, and so on...)

Re:Too bad (2, Informative)

iminplaya (723125) | more than 7 years ago | (#18729283)

...because there was no fire.

Correction [about.com]

FTL: The plane's high-octane fuel exploded, hurtling flames down the side of the building and inside through hallways and stairwells all the way down to the 75th floor.

Re:Too bad (1)

YrWrstNtmr (564987) | more than 7 years ago | (#18730619)

The plane's high-octane fuel exploded, hurtling flames down the side of the building and inside through hallways and stairwells all the way down to the 75th floor.

There is a LOT of difference between a B-25 hitting the ESB, and a 757 hitting the WTC.
A B-25 is about the weight of a current F-16. Fully fueled, it carries about 700 gallons. A 757 has a MTOW of 272,500lb, and fully fueled carries 11,000+ gallons of fuel.
About the same difference as a pickup truck and a semi.

The ESB is a hard outer shell building, the WTC is a soft skin, internal structure building.

Re:Too bad (1)

Deadstick (535032) | more than 7 years ago | (#18732411)

What's more, the B-25 was at the end of its planned flight, probably with no more than a couple of hundred gallons aboard.

Incidentally, the reference to "high-octane fuel" is pretty dull-witted. Increasing the octane rating of a fuel has essentially no effect on the energy content or the combustion temperature -- it merely lets you run it in a higher-compression engine, which will put more of the energy into the crankshaft and less out the exhaust pipe. High-octane fire, low-octane fire, same difference.

rj

Re:Too bad (0)

Anonymous Coward | more than 7 years ago | (#18735321)

The fires in WTC buildings (which could not burn hot enough to weaken the steel enough to cause a collapse anyhow) did not burn nearly as long as the fires burned in ESB. There are many many many other examples of steel frame skyscrapers catching on fire, but none of them collapsing. None. Ever. WTC7 wasn't even hit by an airplane yet collapsed right into its own footprint.

Re:Too bad (1)

iminplaya (723125) | more than 7 years ago | (#18736811)

I wasn't trying to compare anything. I simply wanted to correct an honest mistake.

Re:Too bad (1)

AJWM (19027) | more than 7 years ago | (#18733785)

Okay, thanks for the info. Make that "no significant fire". Yes, it was significant to the individuals immediately involved, of course, but a good part of the burning fuel (not very much, considering the plane was near the end of its flight) went outside the building. The fire was extinguished.

Other posters have already compared the relative weights and fuel loads of the aircraft. The energy density of "high octane" avgas vs jet fuel is about the same (about 43 MJ/kg), I see more variation between different analyses of same than between avgas and jet fuel.

Re:Too bad (1)

iminplaya (723125) | more than 7 years ago | (#18736777)

I didn't mean to sound harsh or anything, and I wasn't even comparing the two. I was just hoping to avoid confusion and save a bunch of ranting and raving about off topic details(too late for me...) and turning the thread into a political flame fest. I would also think that aerodynamic forces from a good, stiff breeze are a lot more stressful on a structure than a puny airplane, as was evidenced by both incidents. BUT, since I haven't done the math, I wouldn't know.

Re:Too bad (0)

Anonymous Coward | more than 7 years ago | (#18729407)

These scholars [stj911.com] seem to agree with this guy [journalof911studies.com] . There are alot more peer reviewed articles here [journalof911studies.com] and other useful resources here [improbablecollapse.com] .

You should try focusing more on the truth, and less on silly analogies.

Re:Too bad (1)

QuantumG (50515) | more than 7 years ago | (#18729691)

There's 1.5 million structural engineers in the US. Are you seriously trying to say that all of them are "keeping quiet" on this "impossible" event. Pah-lease.

Re:Too bad (0)

Anonymous Coward | more than 7 years ago | (#18729723)

Try actually reading the linked information genius.

Re:Too bad (1)

scottv67 (731709) | more than 7 years ago | (#18730417)

Buildings are not something you should fly planes into.. they're not designed to keep standing up under that kind of stress.

It took me about ten seconds with Google to find numerous pages that describe how the Word Trade Center buildings were designed to keep standing up under that kind of stress.

Statements by Engineers

Engineers who participated in the design of the World Trade Center have stated, since the attack, that the Towers were designed to withstand jetliner collisions. For example, Leslie Robertson, who is featured on many documentaries about the attack, said he "designed it for a (Boeing) 707 to hit it." 2 Statements and documents predating the attack indicate that engineers considered the effects of not only of jetliner impacts, but also of ensuing fires.

John Skilling

John Skilling was the head structural engineer for the World Trade Center. In a 1993 interview, Skilling stated that the Towers were designed to withstand the impact and fires resulting from the collision of a large jetliner such as Boeing 707 or McDonald Douglas DC-8. Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed, ... The building structure would still be there. 3 A white paper released on February 3, 1964 states that the Towers could have withstood impacts of jetliners travelling 600 mph -- a speed greater than the impact speed of either jetliner used on 9/11/01. The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707--DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact. 4


http://911research.wtc7.net/wtc/analysis/design.ht ml [wtc7.net]

Re:Too bad (1)

QuantumG (50515) | more than 7 years ago | (#18730465)

If it was really the case that these buildings shouldn't have fallen down and something like a "controlled demolition" was going on, every structural engineer in the US would be on the phone to the press. There would be a flood of expert opinion saying this was a stunt. There isn't. There's a few crackpots.

Re:Too bad (1)

scottv67 (731709) | more than 7 years ago | (#18730577)

If it was really the case that these buildings shouldn't have fallen down and something like a "controlled demolition" was going on, every structural engineer in the US would be on the phone to the press. There would be a flood of expert opinion saying this was a stunt. There isn't. There's a few crackpots.

So are you saying that Leslie Robertson has been lying on-camera about the design of the WTC buildings in interviews conducted after 9/11? Holy cow! Yes, there are some crackpots, indeed.

Re:Too bad (1)

QuantumG (50515) | more than 7 years ago | (#18730647)

I'm saying it is nonsensical to claim that you can design a building that can withstand a plane crashing into it.. and that a building falling down after a plane crashes into it is a perfectly reasonable thing for a building to do.

What the conspiracy theorists are claiming is that this isn't reasonable and therefore there must have been secret caches of explosives in the building which were systematically detonated sometime after the planes flew into it.

I'm also saying that the stupidity of the second claim is so great that the majority of structural engineers in the world have not even bothered to come forward and refute it because it should be obvious to any reasonable person that it requires no refute.

Re:Too bad (1)

scottv67 (731709) | more than 7 years ago | (#18730815)

I'm saying it is nonsensical to claim that you can design a building that can withstand a plane crashing into it.. and that a building falling down after a plane crashes into it is a perfectly reasonable thing for a building to do.

The WTC buildings were designed to withstand the force of a plane crashing into them. The guy who designed the buildings has said so on-camera. Straight from the horse's mouth. Also, the buildings did withstand the force of the planes that crashed into them on 9/11. The WTC buildings did not topple over seconds after the impact the jets. The tops of the building were not sheared-off by the force of a huge jet traveling at full speed. The WTC buildings absorbed the force of the impact and continued to stand long enough for some people (but not all) to evacuate from the building.

As for why the WTC towers fell an hour after the planes impacted the buildings, I do not know. You ask "why haven't ALL of the structural engineers in the world come forward to expose the conspiracy?" Well, some people have examined the data and proposed that the buildings did not fall due to the impact of the planes:

http://www.journalof911studies.com/articles/Why%20 Indeed%20Did%20the%20WTC%20Buildings%20Completely% 20Collapse%20Jones%20Thermite%20World%20Trade%20Ce nter%20J24.pdf [journalof911studies.com]

We may never know the exact reason why the WTC towers fell but your assertion that "it is nonsensical to claim that you can design a building that can withstand a plane crashing into it" is quite a different problem. You are saying that it is impossible for skyscrapers to be designed to accommodate that sort of impact. That's painting with a pretty wide brush. You are saying that, ignoring any conspiracy theories surrounding 9/11 for a moment, no one anywhere can design a building to meet those specifications. One Slashdotter against ALL of the architects and structural engineers in the world. You should probably produce some very good math at this point to back up your claims.

Re:Too bad (0)

Anonymous Coward | more than 7 years ago | (#18732667)

MANY structural engineers ARE flooding the press with calls/mail/etc. All over the world films like Loose Change are being screened including on major networks. How about Kevin Ryan, an engineer at the company that CERTIFIED THE STEEL USED IN THE WTC? You haven't bothered to do any research at all... I thought this was a site for nerds not jingoists...

"It's not true because I've already made sweeping assumptions based outside of fact." GTFO.

Re:Too bad (1)

MiniMike (234881) | more than 7 years ago | (#18733835)

Information like that only convinces the ignorant. It took me about 10 seconds of searching on Wikipedia (just to make sure I was remembering correctly) to find that the airplanes which crashed into the WTC were Boeing 767's, not 707's. A 767 weighs about 1.5-2 times as much as a 707 (depending on confiuration, empty vs max, etc.), and carries more fuel (based on the much longer operating range). So yes, the WTC were designed to withstand the impact of a jet, a _smaller,_lighter_ jet. It should really be no surprise to anyone that when a much larger jet than the designers anticipated hit them, they weren't able to withstand it. Also, the original design assumptions didn't take into account that insulation would be removed by the impact, and some of the structural members would be directly exposed to the fire. Try looking at all the facts, not just the ones that support whatever conspiracy theory you're trying to believe.

Has anyone else noticed the decline in Bigfoot and Elvis sightings since 9/11? Where have the crackpots all gone?

Re:Too bad (0)

Anonymous Coward | more than 7 years ago | (#18734495)

The situation the buildings were designed to handle actually involves MORE kinetic energy due to the higher cruising speed of a 707. Maybe you should follow your own advice.

Re:Too bad (2, Insightful)

AJWM (19027) | more than 7 years ago | (#18729163)

I'm not sure why that got modded funny.

Think about why the World Trade Center towers collapsed. (Hint: something to do with the effect of sustained high temperature kerosene fire on the strength of structural steel.)

Re:Too bad (1, Insightful)

Anonymous Coward | more than 7 years ago | (#18729473)

Please pull your head out of your ass, and try this post [slashdot.org] for a dose of reality.

Re:Too bad (1)

limecat4eva (1055464) | more than 7 years ago | (#18730873)

Are you one of those 9/11 dorks who heckles people on the subway platform claiming that 7WTC was wired with explosives in advance and then demolished on purpose? Yeah, well, by whom? The White House? You think anyone in this administration is competent enough to plan and execute such a conspiracy? By Silverstein? The FDNY? You're a real fucktard.

BTW, a friend of mine was an IT guy in that building (7 WTC) supervising vast remodeling of several floors, for years up to and including 9/11. If there were explosives strapped to the beams, I'd think he would have seen them--oh wait, but he's part of the conspiracy, too, yeah? Again, you're a fucktard.

Re:Too bad (1)

BLQWME (791611) | more than 7 years ago | (#18732241)

You are a narrow-minded son of a bitch. In light of all of the coincidences that have been brought to light, you have the balls to call some one a fucktard. Why don't you start some background searches yourself. As much as it would hurt you to watch "Loose Change" or one of the other pseudo-documentaries out there, there are some valid things to look for. One of them being PNAC. BTW, Cheney and Rumsfeld were charter members of PNAC. Start there, then try realizing that less than two hours after 9/11 happened, Rumsfeld called for the invasion of Iraq. Wow! Al Qaeda hits the WTC and now we go into Iraq? You better wake up and start YOUR research fucktard. You might find some old plans out there for going to war with Cuba by doing some terrorist activities in Miami and blaming it on the Cubans. Maybe you can look at a map and plot where we have troops and see what country they surround. Then maybe you will see what ALL of this is really about. Don't forget jackass- this is the same govt that denies Area 51 exists and people dying from handling hazmats there can't file for claims because the govt says that place doesn't exist.

Re:Too bad (1)

limecat4eva (1055464) | more than 7 years ago | (#18732517)

If you think anyone in this administration has the competence to perpetrate a coverup on this scale, you seriously need to pull your head from your ass.

Re:Too bad (1)

limecat4eva (1055464) | more than 7 years ago | (#18732567)

Also, how old are you, twelve? Seems like you'd benefit from a little more life experience before deciding to hatch overcomplicated theories that the 99% of people who have ever left their mom's basement understand are wholly implausible. You fucking retard.

INSIGHTFUL? HAHAHAHAHAHA (0)

Anonymous Coward | more than 7 years ago | (#18732297)

The parent makes a post based on NO SOLID FACT and it's insightful? What temperatures are necessary to melt structural steel at all, let alone to melt the steel in those buildings to the point of causing collapse? Can jet fuel fires reach those temperatures?

WAKE UP. The official story is a "conspiracy theory" requiring you to believe the first three steel frame buildings in history to collapse to the ground as a result of fire did so on 9/11. One of those buildings was not even hit by a plane.

Yeah. Insightful. Like a fox.

Re:INSIGHTFUL? (1)

AJWM (19027) | more than 7 years ago | (#18733643)

What temperatures are necessary to melt structural steel at all,

Who said anything about melt?

Structural steel -- almost any metal -- loses strength as it heats up. That's why a blacksmith heats up a piece of iron or steel before working it. It just needed to get hot enough to where the loss of strength was greater than the safety margin built in to the design. That's far short of melting point.

What a maroon.

So they shake it... (1)

aldo.gs (985038) | more than 7 years ago | (#18728981)

...but what about the stroke?

I really need some sleep.

Beowulf (1)

SnarfQuest (469614) | more than 7 years ago | (#18729003)

Ok. Enough stories about using three PS3's in a beowulf cluster as a supercomputer.

Late again dirty yankees (1)

bananaendian (928499) | more than 7 years ago | (#18729077)

Yawn! The Japanese have had several thousend ton skyscrapers sitting on springs hooked up permanently with sensors, dynamic counter-weights and dampers for decades now...

Re:Late again dirty yankees (1)

SillyNickName4me (760022) | more than 7 years ago | (#18729849)

And the Byzantines have built some amazingly earthquake resistent and very large building some 1600 years ago or thereabout. Despite some large earthquakes hiting what we now know as Istambul, their building is still standing. The question is.. was this the result of (educated) guessing or actual knowledge.

Re:Late again dirty yankees (1)

sponga (739683) | more than 7 years ago | (#18733081)

There was also a scandal involving a world known Japanese company Apa Group who built two big hotels that were condemned because they did not meet earthquake code regulation; the leading engineer who is also world known was also convicted of not making many residental structures up to earthquake code.

Japanese have been dealing with earthquakes a lot more seriously especially ever since the massive blow they took with Kobe, Japan. Unfortunately until than the Japanese relied on brute strength in structual engineering for a long time until the Kobe disaster.

It actually took some American engineers to come over there to survey the 1995 earthquake in Kobe, Japan and they had to tell the Japanese that their way of building with brute strength and support columns was very flawed; lots of government money poured in after that and since than they have lead the world in research.

If you have the Discovery channel they did an amazing coverage of some new Japanese building where they literally have this hundred ton steel/lead ball inside the top of the building used as a dynamic counter weight that shifts side to side; they even showed future plans for a mile high building that would use a giant several hundred ton ball even four times bigger than the original but toward the end of the documentary they said it just didn't make sense because it would take up so much office space at the top of the building it would not be practical.

Only 275 Tons? (1)

Jeff Fohl (597433) | more than 7 years ago | (#18729093)

The building is only 275 tons? I am no building engineer, but that seems pretty light weight for a building, doesn't it?

Re:Only 275 Tons? (0)

Anonymous Coward | more than 7 years ago | (#18729227)

The building is only 275 tons? I am no building engineer, but that seems pretty light weight for a building, doesn't it?


It was based on European architecture, not American. Not everyone is obese.

Re:Only 275 Tons? (0)

Anonymous Coward | more than 7 years ago | (#18731525)

Sounds light to me as well. My house (a former communications center, built to withstand nearby bomb blasts -- but not a direct hit) weighs some 700 tons. Of course, not many single-story buildings have solid concrete walls that are 12-16 inches thick.

List of Movies and Other Multimedia (2, Informative)

stikves (127823) | more than 7 years ago | (#18729099)

There is a list of all the media (including several movies) on their press release site:
http://visservices.sdsc.edu/projects/nees/article. php [sdsc.edu]

This includes both real and simulated building captures (and several overlayed ones).

Re:List of Movies and Other Multimedia (1)

celerityfm (181760) | more than 7 years ago | (#18735959)

Now thats what I'm talking about! "HD" quality video of this building getting shook. Unreal- when it swayed I was just like O_o

knowwhatimean?

Thanks for the link

Is it Accurate? (1, Interesting)

Anonymous Coward | more than 7 years ago | (#18729101)

As any resident of an earthquake prone area will tell you, earthquakes don't only have lateral motion, but vertical motion as well ... Northridge was not exception. It seems like this simulation, and others, only simulate lateral forces. Catastrophic failures can and do happen in structures due to vertical forces (witness the collapse of the freeway in Oakland). Why do these shake tables not simulate vertical motion as well?

Re:Is it Accurate? (0)

Anonymous Coward | more than 7 years ago | (#18729333)

Technically, yes, they do have vertical motions, but normally they do not play a large role. Buildings have large factors of safety built into their vertical system, frequently the factors multiply up to two, which would allow for a 1g vertical acceleration.

Speaking about the Northridge earthquake you are mentioning, it failed due to the lateral (horizontal) movements. The structure could have taken 2.5g or more (read 1.5g additional vertical) before it would have failed. The problem was that it was not built AT ALL for lateral, the code at the time of construction did not anticipate the types of failure mechanisms that occurred in the structure.

From a Structural Engineer

Re:Is it Accurate? (1)

The Real Nem (793299) | more than 7 years ago | (#18729377)

I'm no engineer, but if horizontally shifting 275 tons with any kind of vivacity is a challenge, vertically shifting it must be a nightmare. Imagine the stress, and then doing the two in parallel...

Structural engineers built it, not comp. engineers (2, Funny)

fname (199759) | more than 7 years ago | (#18729121)

As reported in every other story, But this was no ordinary earthquake. In a groundbreaking series of tests, engineering researchers from UC San Diego's Jacobs School of Engineering jarred a full-size 275-ton building erected on a shake table, duplicating ground motions recorded during the January 17, 1994 Northridge earthquake in Los Angeles, California. The guys at the supercomputer center played a role, but they didn't build the building or run the test. It was obviously folks from the Structural Engineering department.

I'll chalk that mistake to sloth, not pride. No doubt, some are envious of the attention the lead guys get, but the greedy bastards deserve it. In their wrath, they shake the building, lusting for its fall and gluttonous for the massive data.

Re:Structural engineers built it, not comp. engine (1)

Karthikkito (970850) | more than 7 years ago | (#18729251)

For those who didn't get the references in the above post, the on-campus shake table at UCSD has neon signs what flash the vices and virtues late into the night: http://stuartcollection.ucsd.edu/StuartCollection/ nauman/49530049.jpg [ucsd.edu]

Re:Structural engineers built it, not comp. engine (0)

Anonymous Coward | more than 7 years ago | (#18729297)

No, that shake table is indoors and construction would be impossible. The real behomith is the one they have on the military base. It is an outdoor shake table, which means that one is able to build anything with anything. The indoor table is limited by the size of the crane and the size of the building.

Real link for those which want a clickable link (1)

aepervius (535155) | more than 7 years ago | (#18729211)

Posted as Anonymous coward for obvious reason

Link corrected [eurekalert.org]

Geez I am stupid (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#18729245)

I am laughing really hard now :). 1) hit submit instead of preview 2) forgot to click anom coward 3) link is not even working. 4) anyway other had already posted a corrected link.
At least with that amount of self ridicule i can't stoop lower :P.

Anyway here it is as promised : linky [eurekalert.org]

heh heh (0)

Anonymous Coward | more than 7 years ago | (#18729313)

heh heh don't sweat it, it happens to the best of us ; )

but i don't understand why you bothered with AC for the follow-up ...

Re:Real link for those which want a clickable link (1)

Karthikkito (970850) | more than 7 years ago | (#18729273)

Hello, Mr. AC!

how to destroy a building (0)

Anonymous Coward | more than 7 years ago | (#18729325)

This reminds me of a devious stategy for destroying a building. Basically if you can determine the resonant frequency of the building, you could make a device that oscillates at that frequency. Strap the device (or devices) onto the building and eventually the building will shake itself to pieces.

Re:how to destroy a building (1)

Tomfrh (719891) | more than 7 years ago | (#18730383)

Those devices are a myth.

Fly a plane into it, please (0)

Anonymous Coward | more than 7 years ago | (#18729495)

After they shake it, can they fly a plane into it and see if it collapses or is even close to it?

Tesla (1)

seven of five (578993) | more than 7 years ago | (#18730763)

I remember reading about how Tesla could calculate the resonant period of a building, then set up a small mechanical oscillator on an I-beam or some such, and make the whole building shake (eventually) via positive feedback.

Re:Tesla (1)

profplump (309017) | more than 7 years ago | (#18732513)

Now remember reading about how that doesn't actually work due to http://en.wikipedia.org/wiki/Damping [wikipedia.org] and stop telling people about it.

You could make most buildings reach a state of resonance given the right conditions, but one of those conditions is an oscillator that imparts enough energy to overcome the damping effect of, say, having a foundation buried in the ground.

I agree that there's some wave reflection from the foundation, but there's also a lot of less-than-rigid dirt around the footings, and it will absorb a lot of energy. Which is good, otherwise buidlings would be in danger of falling down from all sorts of low-energy oscillations, like people walking.

Next generation experiementers plan to ... (1)

Organic Brain Damage (863655) | more than 7 years ago | (#18730995)

...put a 275-ton super computer on the shake table to cut out the middlemen.

log houses? (1)

sraak (557865) | more than 7 years ago | (#18735551)

finnish company (http://www.honkatalot.fi/eng/index.html) has sold many log homes/houses to japan. why? earthquakes do not destroy those at all: if the worst happens, you just use few tools, few guys/gals to help you, and in few hours your log house is fixed. (i have no time to explain how, but ask here, and later i will explain how to fix it *fast* after (almost) any kind of EQ.)
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