Technical question on WTC collapse

[Proud American]

Hey, 'I shouldn't be proud to be a yank', it makes a difference when the perps were insiders....

Hey poop for brains...are you really that stupid?......

And for the record, get your name calling "straight".."Yanks" are people who live in the section of this country called NEW ENGLAND...I have never even been to New England,let alone being from there...so please get it right before you spew your uneducated nonsense............

 

[Proud American]

Well Logic, I have to give you credit about one thing, you actually asked a question that can be answered, that is how long does the steel have to be exposed to the heat, to lose 50% of its strength. Personally, I have no idea. I would imagine the density and thickness of the steel matters. But at least you asked a reasonable question.

The other issue about this thread is the rush to explain, I'm sure there are plenty of scientific explanations as to the why and how the towers collapsed, but a major issue hasn't been brought up. The WTC disaster wasn't a controlled experiment in a controlled environment. Many things can happen that cannot be explained. And at that point, it's "best guess".

One can observe an experiment in a controlled situation and still have things go wrong that cannot be explained.

And everyone points to the 9/11 Commission Report to somehow make a case of a conspiracy. That report is NOT a technical document, it is a summary of the events and the sequence in which they unfolded.

All this scientific jargon has been answered by the National Institute of Standards and Techonology's Final Report http://wtc.nist.gov/NISTNCSTAR1CollapseofTowers.pdf and the Companion Reports http://wtc.nist.gov/reports_october05.htm

Hundreds of scientists (specialists) in their respective fields have already answered these questions.

Ahh but alas....some people just can't or refuse to read.......

 

[Logic 7]

steel is highly conductive of both heat and electricity. If the flames were at this temperature around the steel, the steel would reach that same temperature in seconds, a minute at the outside. A large explosion like that could certainly generate temperatures high enough to weaken that steel.

Basically skyscrapers were never designed with aeroplane collisions in mind. There is no way you could expect the WTC to withstand such treatment

True steel is highly conductive, however the steel wouldnt reach the same tempature all along, instead it will be difused, and wtc could withstand 3 jetliner impact from what the planes were in the 70's according to wtc construction manager.

 

[Logic 7]

A very important fact is that steel doesn't burn.

Ok then, how long will it need to heat for the steel to loose 50% of his strenght?

 

[Logic 7]

Well Logic, I have to give you credit about one thing, you actually asked a question that can be answered, that is how long does the steel have to be exposed to the heat, to lose 50% of its strength. Personally, I have no idea. I would imagine the density and thickness of the steel matters. But at least you asked a reasonable question.

The other issue about this thread is the rush to explain, I'm sure there are plenty of scientific explanations as to the why and how the towers collapsed, but a major issue hasn't been brought up. The WTC disaster wasn't a controlled experiment in a controlled environment. Many things can happen that cannot be explained. And at that point, it's "best guess".

One can observe an experiment in a controlled situation and still have things go wrong that cannot be explained.

And everyone points to the 9/11 Commission Report to somehow make a case of a conspiracy. That report is NOT a technical document, it is a summary of the events and the sequence in which they unfolded.

All this scientific jargon has been answered by the National Institute of Standards and Techonology's Final Report http://wtc.nist.gov/NISTNCSTAR1CollapseofTowers.pdf and the Companion Reports http://wtc.nist.gov/reports_october05.htm

Hundreds of scientists (specialists) in their respective fields have already answered these questions.

Well thankx, i totally agree that the 9-11 comission report isnt a technical document.Maybe NIST and other scientist groups can explain the collapse, but i would rather go with an international , independant investigation at all levels, including scientist, sorry i don't trust any organisation who are related to the US governement, and i think just the anthrax event that occured after 9-11, is enought to suspect everyone in the US governement for cover up and being involved.

 

[Sassylassie]

Well my husband went over the post the Juan posted and this is his Rebuttal:

The designers assumed the aircraft was operating normally. Here the theory begins to unravel. The designers assumed the aircraft was operating normally and as such was traveling at its cruise speed. Where did the designers calculate this impact to occur? The top, middle or base of the building? What were the positions of the engine levers of the 767 vs a 707 in cruise?

Fact. The plane was in a descent when it hit the towers. The engine levers were probably fully forward in order to maximize the ballistic effect of the impact. The 767 has 2 engines capable of providing 63,300 lbs of thrust each, vice the 707 having 4 engines capable of 18,000 lbs of thrust each. A significant deficit when it comes to power to weight ratio. But of course if one assumes an accidental cruise speed collision then these factors don’t apply. The cross section of the 707 vs the 767 is 3.54 meters in dia for the 707 and 5.03 meters for the 767. Using a simplified kinetic energy formula is an excellent way to end run the facts when it comes to damage assessment.

Stating that other high-rise buildings have suffered significantly more serious fires and did not collapse is the type of broad brush generalization that one would expect from some academic who is more worried about being published than clouding a comparison with facts. Show the type of buildings that were used in the comparison, of course these buildings were also hit by aircraft and the fires started by ignition of large quantities of aviation fuel. Of course for those who blame Bush for the September 11 attacks also believe that “Heat does not effect the structural integrity of steel”. Ever heard of a Blow Torch/Weldiers torch tin foilers?

 

[hermanntrude]

I give up.

It's rediculous to think that anyone but the terrorists decided to attack those buildings.

Bush couldn't find his own arse with both hands, let alone some sneaky trick to get the public on his side.

there will be no further from me on this subject

 

[#juan]

Well my husband went over the post the Juan posted and this is his Rebuttal:

The designers assumed the aircraft was operating normally. Here the theory begins to unravel. The designers assumed the aircraft was operating normally and as such was traveling at its cruise speed. Where did the designers calculate this impact to occur? The top, middle or base of the building? What were the positions of the engine levers of the 767 vs a 707 in cruise?

Fact. The plane was in a descent when it hit the towers. The engine levers were probably fully forward in order to maximize the ballistic effect of the impact. The 767 has 2 engines capable of providing 63,300 lbs of thrust each, vice the 707 having 4 engines capable of 18,000 lbs of thrust each. A significant deficit when it comes to power to weight ratio. But of course if one assumes an accidental cruise speed collision then these factors don’t apply. The cross section of the 707 vs the 767 is 3.54 meters in dia for the 707 and 5.03 meters for the 767. Using a simplified kinetic energy formula is an excellent way to end run the facts when it comes to damage assessment.

Stating that other high-rise buildings have suffered significantly more serious fires and did not collapse is the type of broad brush generalization that one would expect from some academic who is more worried about being published than clouding a comparison with facts. Show the type of buildings that were used in the comparison, of course these buildings were also hit by aircraft and the fires started by ignition of large quantities of aviation fuel. Of course for those who blame Bush for the September 11 attacks also believe that “Heat does not effect the structural integrity of steel”. Ever heard of a Blow Torch/Weldiers torch tin foilers?

First of all I posted that article because I thought it was an interesting comparison between the 707 that was taken into consideration by the building designers, and the 767 that hit the tower. I didn't post it to strengthen any conspiracy theory. On this particular subject, conspiracy theories have been beaten to death.

Having taped the events of 9/11, and watched them till I was sick of them, My only conclusion was that on one of the crashes, it appeared that the heavier aircraft components,the engines, undercarriage, etc., and most of the jet fuel hurled out of the building through the adjacent wall.

I have no idea where the throttles were positioned, or how fast the aircraft were going. It did not appear that the aircraft were diving but I'm sure, that by now, someone has already calculated the exact speed of each aircraft.

One lesson that I hope has been learned, is that the stairwell framework should be covered with something more than just gyprock, that was apparently blown into the stairwells by the compression wave when the aircraft came through the walls, and created impassible barriers for people trying to get out of the building.

Cheers.

 

[Proud American]

I give up.

It's rediculous to think that anyone but the terrorists decided to attack those buildings.

Bush couldn't find his own arse with both hands, let alone some sneaky trick to get the public on his side.

there will be no further from me on this subject

LOL!!!! Now that is nothing short of the TRUTH!!!!!!

 

[CDNBear]

Interesting article


THE WTC WAS DESIGNED TO SURVIVE
THE IMPACT OF A BOEING 767.
Fact. The twin towers were designed to withstand a collision with a Boeing 707.

The maximum takeoff weight for a Boeing 707-320B is 336,000 pounds.
The maximum takeoff weight for a Boeing 767-200ER is 395,000 pounds.

The wingspan of a Boeing 707 is 146 feet.
The wingspan of a Boeing 767 is 156 feet.

The length of a Boeing 707 is 153 feet.
The length of a Boeing 767 is 159 feet.

The Boeing 707 could carry 23,000 gallons of fuel.
The Boeing 767 could carry 23,980 gallons of fuel.

The cruise speed of a Boeing 707 is 607 mph = 890 ft/s,
The cruise speed of a Boeing 767 is 530 mph = 777 ft/s.

So, the Boeing 707 and 767 are very similar aircraft, with the main differences being that the 767 is slightly heavier and the 707 is faster.

In designing the towers to withstand the impact of a Boeing 707, the designers would have assumed that the aircraft was operated normally. So they would have assumed that the aircraft was traveling at its cruise speed and not at the break neck speed of some kamikaze. With this in mind, we can calculate the energy that the plane would impart to the towers in any accidental collision.

The kinetic energy released by the impact of a Boeing 707 at cruise speed is
= 0.5 x 336,000 x (890)^2/32.174
= 4.136 billion ft lbs force (5,607,720 Kilojoules).

The kinetic energy released by the impact of a Boeing 767 at cruise speed is
= 0.5 x 395,000 x (777)^2/32.174
= 3.706 billion ft lbs force (5,024,650 Kilojoules).

From this, we see that under normal flying conditions, a Boeing 707 would smash into the WTC with about 10 percent more energy than would the slightly heavier Boeing 767. That is, under normal flying conditions, a Boeing 707 would do more damage than a Boeing 767.

In conclusion we can say that if the towers were designed to survive the impact of a Boeing 707, then they were necessarily designed to survive the impact of a Boeing 767.

So what can be said about the actual impacts?

The speed of impact of AA Flight 11 was 470 mph = 689 ft/s.
The speed of impact of UA Flight 175 was 590 mph = 865 ft/s.

The kinetic energy released by the impact of AA Flight 11 was
= 0.5 x 395,000 x (689)^2/32.174
= 2.914 billion ft lbs force (3,950,950 Kilojoules).

This is well within limits that the towers were built to survive. So why did the North tower fall?

The kinetic energy released by the impact of UA Flight 175 was
= 0.5 x 395,000 x (865)^2/32.174
= 4.593 billion ft lbs force (6,227,270 Kilojoules).

This is within 10 percent of the energy released by the impact of a Boeing 707 at cruise speed. So, it is also a surprise that the 767 impact caused the South tower to fall.

Overall, it comes as a great surprise that the impact of a Boeing 767 bought down either tower. Indeed, many experts are on record as saying that the towers would survive the impact of the larger and faster Boeing 747. In this regard, see professor Astaneh-Asl's simulation of the crash of the much, much larger and heavier Boeing 747 with the World Trade Center. Professor Astaneh-Asl teaches at the University of California, Berkeley.

Although the jet fuel fires have been ruled out as the cause of the collapses, it should still be pointed out that the fuel capacities of the Boeing 707 and the Boeing 767 are essentially the same. And in any case, it has been estimated that both UA Flight 175 and AA Flight 11 were carrying about 10,000 gallons of fuel when they impacted. This is well below the 23,000 gallon capacity of a Boeing 707 or 767. Thus the amount of fuel that exploded and burnt on September 11 was envisaged by those who designed the towers. Consequently, the towers were designed to survive such fires. It should also be mentioned that other high-rise buildings have suffered significantly more serious fires than those of the twin towers on September 11, and did not collapse.

At present, I am working with Government of Canada employed Engineers and Architecs. They are the most briliant men and women in the world. They told me so.

When I served in the Army, we had an Engineer order the placement or our restroom facilities directly up stream from where we were getting our drinking water.

I don't even now where to begin in trying to tell you about the horror stories of what I and many others of my ilk have had to endure, or suffer through in trying to explain to an Engineer or Architect about what is or is not possible in the practical. They got all the theory in the universe. Here in the 3D world it amounts to a hill of shyte.

As a professional welder/fabricator, with 20 years of experience in welding, working with and manipulating steel, the past 3 as a business owner in the profession, I can assure you. Most Engineers and Architects, with all their glorious degrees and knowledge, haven't got clue one about the practical application of the theory.

They and you, can go crunch all the numbers you want. When the sh*t hits the fan or the plane hits the building in this case, it's a roll of the dice. There is no imperical data to prove other wise...period.

 

[CDNBear]

Again, simply because it was designed to withstand a jet crash does not mean it will.

The Tacoma Narrows Bridge was supposed to withstand wind. It did not.

http://www.enm.bris.ac.uk/research/nonlinear/tacoma/tacoma.html

We need more post from you, LMFFAO. What a completely accurate description of the glorious knowlege of Engineers.

 

[CDNBear]

PLEASE inform, because I have seen nothing but "guesstimates" so far...and really does it matter? Whether the planes caused it, or whether the perps planted bombs on the inside, is irrelevant....

Absolutelt PA. Here here.

 

[CDNBear]

Ok then, how long will it need to heat for the steel to loose 50% of his strenght?

Seconds. If I use a rose bud, which it a torch tip that difuses heat over a greater area then a torch cutting tip. I can heat a 1 inch thick piece of STUCTURAL steel in seconds, to the point at which I could change it's shape with a chip-n-pick or small hammer.

The building burned for an hour at temps just below what I would use to cut, manipulate or weld STRUCTURAL steel. Given the damage from the impact and the addition of the intense heat, it was gunna come down.

 

[fuzzylogix]

What is unexplained in 9/11 is the apparent lack of desire for the US to fully investigate and understand how the towers collapsed. Any other mass structural failure of this sort, be it from a natural disaster or terrorism in the past has been massively investigated in order to prevent the same occurence.


BUT FEMA assembled a team of investigators that were not allowed to even enter Ground Zero. They were given only a few of the metal structures to examine and were only given from October 7-12 to give a report. Only ELEVEN days after the event, the city had signed a deal selling the steel and shipped it off to blast furnaces in India and China.

The buildings may well have had bombs in them timed to go off at the time of impact. All evidence points to this possibility with features of thermite ( a demolition blasting component) being found on some of the residua. Why should the government have wanted to suppress this??? If the building was bombed as well, then why would the assumption be that it was the US government and not Al Quaeda too? Why would the US not want to know if there were bombs as well as planes? surely that would help them in increasing security levels in buildings if they figured out how and where bombs were placed. If there were no bombs, then why would the US not want to study in more detail just how the towers did collapse so neatly into their own footprints. Why the rush to get rid of the evidence???? When a plane crashes, we collect every little piece and spend years piecing the story together before we melt down the metal. Why was such a more catastrophic event given so little time for investigation?????

 

[CDNBear]

My only guess is, the immense loss of life, and the over whelming video evidence that planes had hit the buildings.

 

[fuzzylogix]

The immense tragic loss of life and enormity of this should have prompted a more massive investigation than had ever been conducted before. Noone would have criticized the government taking longer to clean up if it was in order to do a thorough investigation. And the cleanup could still have taken the wreckage to another site for storage and full analysis. In fact, many victim's families demanded a fuller investigation.

Video footage is not an analysis and is used as only one component of investigation. Chemical analyses are performed on the wreckage to detect bomb components. Look at the Oklahoma bombing. They went through the entire wreckage to find one fragment of a license plate that led them to the rented van.

 

[I think not]

What is unexplained in 9/11 is the apparent lack of desire for the US to fully investigate and understand how the towers collapsed. Any other mass structural failure of this sort, be it from a natural disaster or terrorism in the past has been massively investigated in order to prevent the same occurence.


BUT FEMA assembled a team of investigators that were not allowed to even enter Ground Zero. They were given only a few of the metal structures to examine and were only given from October 7-12 to give a report. Only ELEVEN days after the event, the city had signed a deal selling the steel and shipped it off to blast furnaces in India and China.

The buildings may well have had bombs in them timed to go off at the time of impact. All evidence points to this possibility with features of thermite ( a demolition blasting component) being found on some of the residua. Why should the government have wanted to suppress this??? If the building was bombed as well, then why would the assumption be that it was the US government and not Al Quaeda too? Why would the US not want to know if there were bombs as well as planes? surely that would help them in increasing security levels in buildings if they figured out how and where bombs were placed. If there were no bombs, then why would the US not want to study in more detail just how the towers did collapse so neatly into their own footprints. Why the rush to get rid of the evidence???? When a plane crashes, we collect every little piece and spend years piecing the story together before we melt down the metal. Why was such a more catastrophic event given so little time for investigation?????

You're clueless, quit while you're ahead.

 

[fuzzylogix]

ITN, For a supposed intellectual, I would expect a better rebuttal than "YOU'RE CLUELESS"

Why am I clueless?

The question about the investigation is an entirely valid one. EVERY other event from a person getting hit crossing the street to a bridge collapsing has a need for thorough review. Your immediate dismissal of my point is ridiculous- why would you as an American NOT expect and demand a thorough investigation??


If structural defects WERE found to be the cause of the collapse, then shouldn't civil engineers and architects know about this so that they can consider the implications in future buildings?

And if there WERE bombs in the buildings, then shouldn't we know about it? Why would the government NOT want to know about it? Well there are two possibilities for this, neither of which is completely insane, and neither of which the government would want you to know about:


1. TERRRORISTS PLANTED BOMBS: Well, I guess that would indicate that building security was so slack that the government would have to face the fear and anger of the population in knowing that terrorists had gained access to the buildings. Even so, the government would likely accept the populace knowing- after all they have had other mistakes like New Orleans brought out into the open.

2. THE GOVERNMENT PLANTED THE BOMBS: Now up to this point, all you anti conspiracy theorists have focussed on the unlikelihood of the government provoking a war by blowing up its own buildings, and that the planes existed and do seem to be part of a terrorist activity.


BUT SUPPOSE.....the bombs were not placed as a governmental plot to bring the buildings down, but as a CONTINGENCY plan. Suppose, knowing that there was a possibility that the buildings could come under a terrorist attack like this, the government realized that it could NOT have the buildings topple sideways. Suppose also, being a building of high information sensitivity, the government decided that it could NOT have the buildings fall into terrorist hands. Suppose the government decided that in this event, the buildings would be imploded to ensure that the collapse of the buildings would create as minimal destruction as possible.

Demolition experts will tell you that the toppling of buildings into their bases (footprints) is a very difficult thing to do and only a few companies around the world will actually deal with buildings that have to be toppled straight down. Most buildings tip sideways. Perhaps the towers were preset with bombs that were set off when the tops were angling, a sign that they were likely to fall sideways.

Perhaps in many cities, buildings of such height or with such sensitive security issues are fitted out with bombs as contingency measures to ensure the ability to implode the buildings vertically if necessary.

THIS would NOT be so far fetched, but of course would be something the US government would not want to have to face the populace about.

Dont be so narrowminded, ITN. Sometimes you have to think OUTSIDE the box.

 

[I think not]

I'm not narrowminded fuzzy. I said you're clueless because you're towing the conspiracy line.

http://www.pbs.org/wgbh/nova/wtc/cons-flash.html

 

[Logic 7]

Seconds. If I use a rose bud, which it a torch tip that difuses heat over a greater area then a torch cutting tip. I can heat a 1 inch thick piece of STUCTURAL steel in seconds, to the point at which I could change it's shape with a chip-n-pick or small hammer.

The building burned for an hour at temps just below what I would use to cut, manipulate or weld STRUCTURAL steel. Given the damage from the impact and the addition of the intense heat, it was gunna come down.

it would need stable and very intense fire, for the fire to be not defuse,which didnt happen at all on 9-11.