Until 911 - Fire has never collapsed a skyscraper

Originally posted by JaxonRoberts
reply to post by Rigel Kent

 

Perhaps you saw the National Geographic special on 9/11 conspiracies? They conducted several scientific tests to prove or disprove various theories. One such experiment involved beams just like those in the WTC, and a jet fuel fire. In less than 5 minutes, the beam lost it's structural integrity. Now, while some of the fuel burned away instantly, most did not. The fireball would have been 5 times the size had it all burned off at once.

SIGHS,,,,
Is that the best you can do? National Geographic? OMG if I had seen it, I wouldnt be quoting it on here as gospel. What are you going to quote next, Mythbusters?
As I have pointed out before, I am not about to believe some crap from the tube peddled by a company 67% owned by Bilderberger and Illuminatiist; Ruppert Murdoch. I do like their wildlife stuff though
Do you honestly think that Murdoch would put anything out about this subject other than stuff which is in line with the original Govt BS explanations?

I know this sounds mightier than thou and I am sure you are a smart guy n all but I think that there is a lot of truth in the phraze that TV really is just education for the masses. What was it? He who controlls the media controlls the masses... something like that, anyway thanks for your time Jaxon.

PEACE,
RK

Originally posted by Rigel Kent

Originally posted by jthomas

Originally posted by Rigel Kent
Excepting the three 9-11 collapses, no fire, however severe, has ever caused a steel-framed high-rise building to collapse.

FALSE.

Hundreds upon hundreds of steel-framed buildings collapsed due to fire alone during the firebombings of cities in World War II, including Dresden, Berlin, and Tokyo.

These are documented and preserved in museums in those cities as well as in photographs at the Imperial War Museum in London and preserved steel at the Edo Museum in Tokyo.

This subject has been beatened to death and settled years ago.

I dont deny that many buildings collapsed in these places but they were as a result of sustained aerial bombardment with high explosive fire incendiary bombs and the majority had lots of timber in their roofs which will ultimately collapse in fires under the weight of the tiles. Brick walls become unstable when the fllorboards and supporting joists burn away as they are no longer "tied-in" and therefore collapse.

The subject of this thread is about steel framed skyscrapers not buildings made from brick, cement and wood.

In 1945 I do not know of any steel reinforced skyscrapers in the cities that you named. If you can provide references that show such buildings collapsed as a result of fire I would be happy to review it,

Read my post again.

I am talking about steel-framed structures that collapsed solely due to unfought fires.

You may go your library or contact the museums directly for all the information you want.

Nonetheless, your claim is false and you may research that just as easily as we all have. Your claim has been refuted repeatedly. You just have to understand that just repeating a debunked claim does not - as the 9/11 Truth Movement LOVES to claim - make it legitimate again. You don't know how many times over the last 8 years your very same claim comes up, people spend days refuting it again, only to pop up again a week later someone else.

Learn to do some research rather than just stick to 9/11 conspiracy sites that exist, not for the truth, but to try to achieve their political agenda through any means that gullible people will follow.

reply to post by jthomas


You can keep trying to tell people facts but they will ignore you.Its sad that people are so easily manipulated in to believing what ever a conspiracy site tells them.Your 100% right there has been incidents of steel structures collapsing do to fire.You don't have to melt steel to cause a building to collapse all you have to do is cause the steel to buckle.

To say it never occurred before is just blatantly a lie perpetrated to mislead gullible people. Heres a report you might want to have the people telling you your wrong read!

Historical Survey of Multistory Building Collapses Due to Fire




[edit on 9/21/09 by dragonridr]

How many other skyscrapers have been hit at high speed by commercial jets and doused with burning jet fuel? Maybe it would make a good experiment.

Originally posted by jthomas

Originally posted by Rigel Kent
Excepting the three 9-11 collapses, no fire, however severe, has ever caused a steel-framed high-rise building to collapse.

FALSE.

Hundreds upon hundreds of steel-framed buildings collapsed due to fire alone during the firebombings of cities in World War II, including Dresden, Berlin, and Tokyo.

Multiple points of impact, different construction methodologies, variations in size. Apples to oranges. A better point of reference would be a building built in the same era and same approximate size (Sears Tower) inflicted with jet fuel. As there have been none you cannot compare.

I'm not arguing that the building should not have collapsed, mind you. I disagree with the argument that because no steel enforced building collapsed, none should collapse.

I'm just asking you to not play ignorant and pretend that your example is relevant.

This subject has been beatened to death and settled years ago.

That's beat to death, and, no, it has not been "settled" years ago. Settled by whom? There is no one to "settle" it.

Originally posted by weedwhacker
reply to post by Rigel Kent

 

While a lot of your information is mostly correct, it is laden with the same old already "debunked" stuff -- which seems to have been taken from the multitude of conspiracy sites out there, who haven't yet (or care not to) update their info.

Debunked by whom? We're on ATS now.

There is no credible evidence that any of the alleged hijackers were on any of the jetliners, and considerable evidence to the contrary

Wrong. This comes from the blaoney repeated below...

Several of the alleged hijackers turned up alive after the attack.

Already explained, countless times. It's like if a hijacker named "John Smith" commited the crime...then a lot of other John Smiths out there are sure to stand up and say "It's not me!!! See? I'm still alive!"

Of course, the CT'ers don't want people to realize that different Saudis and Arabs will often have the same names. OR, that they may use aliases.....

Hi Weedwacker! *waves*

Actually the impression came, I feel, from the government putting out reports immediately after 9-11 containing names and photos of individuals associated with the attacks. When you post it to the world it stands to matter that people would want to clear their names (not to mention it must be weird to be declared dead), hence why within four days those falsely implicated came forward.

It also stands to reason that people would become suspicious when they government handled it so sloppily. So... you can't put the blame on the CT'ers entirely as the government fed it by posting photos of individuals before it was appropriate to do so.

The hijacker scenario was operationally almost impossible.

Wrong

What are you saying "wrong" to? The flight or the takeover?

A friend of mine, military, said that he cannot grasp the Pentagon flight where the four hijackers supposedly told a group with a high concentration of military to call their loved ones because they were going to die and the military personnel either did nothing or were not able in mass to overtake the hijackers. To some this is impossible. I, myself, find it improbably. I have been in life-threatening situations before and you are capable of a lot more than you think you would be. With children on a plane? I can't imagine anyone not trying to take back control of the plane using what is in their luggage.

The maneuvers of the jet that targeted the Pentagon required top-gun piloting, if they were even humanly possible.

More nonsense from the CT sites.

Hey Weed! I looked this up when we quit last night and it isn't CT site nonsense. It was covered in the Washington Post.

Hani Hanjour
Obtained a commercial pilot's license in April 1999 from the Federal Aviation Administration. The license expired six months later because he failed to complete a required medical exam. In 1996, he received flight training for a few months at a private school in Scottsdale, Ariz., but did not finish the course because his instructors thought he was not proficient enough. He listed his address as a post office box in Taife, Saudi Arabia, but he also has been linked to addresses in San Diego and Hollywood, Fla. His name was not on the American Airlines manifest for the flight because he may not have had a ticket.

Washington Post 9-2009

In opposition to this his other instructor identified him as good because of his terrain navigation. So one good, one bad. You both chose the theory that suits your theory, I believe Watcher would refer to this as your schema.

The world's media has reported that many of the so-called hijackers "fingered" by the FBI are still alive. For example as soon as 21st September 2001 the BBC (British Broadcasting Cooperation) carried this report:

Yeah. Look at the date there. BBC retracted and amended that story. Research is your friend.

Research done! I checked. The BBC did not retract the story. They wrote a later piece wherein the hijacker's "names" went back to "deceased" and changed a caption in the original story for one of the hijackers. If you can find a retraction it please link up because I want to be accurate with this stuff.

I guess that's my concern is that which Watcher spoke of the other day. We see thing through the looking glass of our schema. To Rigel, the documents add up to something fishy. He sees the flight instructor that says the dude sucked and uses that, you take the Israeli military guy and use that. Perhaps he was a suck pilot when behind a real plane, but was good with visuals? Perhaps he is a fair to middling pilot. The stories conflict.

How do we even know Hanjour flew the plane? What if the military guys as my friend suggested they would do took out at least one of the hijackers--maybe even Hanjour and someone else with better flying experience was behind the wheel?

None of us know because we weren't there. Even the voyage back from West VA according to the link you sent me was based off of nothing in the plane because they had dismantled it. It's all our best guess.

This is to everyone, not Weed.

Instead of dismissing each other and snarking each other why don't we take their evidence and discuss it. If you are going to say something as irrelevant as: This is has been debunked already or This has been covered in another thread...then don't post at all. Ignore the thread if it is old news. Some of us like reading new stuff and when all we get to read is that you won't respond because it is debunked it is really quite disappointing. Either play the hand or don't post. Stop with the: we did this in another thread!

Please.

Jthomas & Dragonrider,
This thread is about "skyscrapers" collapsing due to fire and not multi-storeyed buildings as presented in the Hughes Associates Inc paper to which you linked extracts from. The full title of which is:

Historical Survey of Multi-Story Building Collapses Due to Fire

review the full paper here

www.haifire.com...

2nd para from the paper states:

"Either partial or total failure of the structural framing, members, and/or connections was considered to have met the definition of “collapse.” A multi-story building was defined to consist of 4 or more stories."

whooooaaaahhh lets just hold it there a minute. So according to this so called "paper" which has no date, references or Bibliography section and has not been peer reviewed.

THE PART FAILURE OF A STRUCTURAL MEMBER OR CONNECTION MEETS THE DEFINITION OF "COLLAPSE"

I have read that paper several times and apart from the WTC buildings, there is not one other example of total collapse of a "skyscraper" due to fire.
Out of 22 cases, notwithstanding the 4 WTC buildings listed, there are only 2 buildings which could be construed as skyscrapers and they are:

Page 7:

Jackson street Apartments, Ontario, Canada 21 floors suffered "partial collapse of concrete ceilings" due to fire

Page 8:

No 1, New York Plaza, NYC, 50 floor office building suffered "Connection bolts sheared during fire, causing several steel filler beams on the 33-34th floors to fall and rest on the bottom flanges of their supporting girders."

So there you go, as far as skyscrapers go, in this "paper" at least, those 2 examples are the only ones given.

There is NOTHING in this article which remotely compares to the WTC "collapses" listed.

edited to add: I know that I used the term HIGH RISE at least once and this was an honest mistake on my part. I do understand that when dealing with subjects such as this terminology is all important. So please bear the term "skyscrapers" in mind when presenting your views.

Note to jthomas:
I really resent your arrogant attitude in telling me to learn how to do research, just exactly who do you think you are? My research skills are not the issue here, they served me fine throughout Engineering in University and my subsequent 24 yrs of a proffessional career in the field.

PEACE,
RK


[edit on 21-9-2009 by Rigel Kent]

[edit on 21-9-2009 by Rigel Kent]

Originally posted by Rigel Kent

Note to jthomas:
I really resent your arrogant attitude in telling me to learn how to do research, just exactly who do you think you are? My research skills are not the issue here, they served me fine throughout Engineering in University and my subsequent 24 yrs of a proffessional career in the field.

You didn't do any research before you started this thread and falsely stated: "Until 911 - Fire has never collapsed a skyscraper."

Please don't come here an insult our intelligence next time, ok?

Originally posted by jthomas


You didn't do any research before you started this thread and falsely stated: "Until 911 - Fire has never collapsed a skyscraper."

Please don't come here an insult our intelligence next time, ok?

I'm actually not trying to take anyone's side on this other than the side of "facts", but you actually have not proven his statement wrong. There is not one single instance in that NIST report of a total collapse of a steel multi-story, high-rise, or skyscraper (I don't care how you name it) building other than the WTC buildings.

I think it is disingenuous to take the "partial collapses" noted in that report and try to twist it to show that people's inability to accept the total collapse of the WTC buildings based on the explanation by NIST is unfounded. It's not the partial collapse they don't accept - it's the total. Your list substantiates the claim of no total collapse of a steel building due to fire other than the WTC buildings.

Originally posted by Valhall

Originally posted by jthomas


You didn't do any research before you started this thread and falsely stated: "Until 911 - Fire has never collapsed a skyscraper."

Please don't come here an insult our intelligence next time, ok?

I'm actually not trying to take anyone's side on this other than the side of "facts", but you actually have not proven his statement wrong. There is not one single instance in that NIST report of a total collapse of a steel multi-story, high-rise, or skyscraper (I don't care how you name it) building other than the WTC buildings.

I think it is disingenuous to take the "partial collapses" noted in that report and try to twist it to show that people's inability to accept the total collapse of the WTC buildings based on the explanation by NIST is unfounded. It's not the partial collapse they don't accept - it's the total. Your list substantiates the claim of no total collapse of a steel building due to fire other than the WTC buildings.

Then you would agree that no skyscrapers of the design of the WTC towers have been built, hit by fast-moving Boeing 767's, suffered structural damage, and fires that could not be fought.

So, just what is your point?

reply to post by jthomas


jthomas,

First of all, please understand that It is not my intention to insult anyone's intelligence.

I can assure you that I have done lots of research on this subject for years prior to posting, I have posted many links in an effort to verify my side of the debate throughout this thread, you on the otherhand have posted NONE.

If you do not agree with my views, then that is fine with me but please, since now you are claiming that I have made a false statement, I respectfully request that you post some evidence which contradicts my claim.

PEACE,
RK

reply to post by Watcher-In-The-Shadows

Really? I think it would be harder to cover up shoddy construction techniques/materials. Why? There were far too many honest men/women working on the towers, in my opinion. They would know if there would be corners being cut. Many probably had friends that would be working there. Would they (construction workers) put their family or friends lives on the line? I doubt it.

However, very few people would need be in the "know" to set charges, and it could have been done over a period of weeks, or even years, and perhaps no one would guess that anything nefarious was going on.

Some think that there would be a few whistle blowers come forward if the government was involved. How about whistle blowers if there was shoddy workmanship or shoddy construction materials?

The whole of 9/11 reeks of money. A lot of people made a lot of money in the aftermath of the tragedy of 9/11. How many people made a lot of money in the aftermath of the construction of the towers? Did the Government pay construction workers tons of "hush" money? They paid the families of 9/11 victims tons of "hush" money.

reply to post by saturnsrings


The very basis of your position is based on a generalized character assessment of a large group of people you have never met. And thusly almost assuredly false. Untrustworthy people are everywhere.

[edit on 22-9-2009 by Watcher-In-The-Shadows]

Originally posted by jthomas

Originally posted by Valhall

Originally posted by jthomas


You didn't do any research before you started this thread and falsely stated: "Until 911 - Fire has never collapsed a skyscraper."

Please don't come here an insult our intelligence next time, ok?

I'm actually not trying to take anyone's side on this other than the side of "facts", but you actually have not proven his statement wrong. There is not one single instance in that NIST report of a total collapse of a steel multi-story, high-rise, or skyscraper (I don't care how you name it) building other than the WTC buildings.

I think it is disingenuous to take the "partial collapses" noted in that report and try to twist it to show that people's inability to accept the total collapse of the WTC buildings based on the explanation by NIST is unfounded. It's not the partial collapse they don't accept - it's the total. Your list substantiates the claim of no total collapse of a steel building due to fire other than the WTC buildings.

Then you would agree that no skyscrapers of the design of the WTC towers have been built, hit by fast-moving Boeing 767's, suffered structural damage, and fires that could not be fought.

So, just what is your point?

No, actually, you don't get to extrapolate my words past what they stated. You called him wrong (and a few more negative things) because you claimed your NIST document shows his statement that there have been no other steel buildings totally collapsing from fire is wrong.

I just pointed out that it, in fact, does not. And that's all I said.

Originally posted by jthomas

Originally posted by Rigel Kent

Note to jthomas:
I really resent your arrogant attitude in telling me to learn how to do research, just exactly who do you think you are? My research skills are not the issue here, they served me fine throughout Engineering in University and my subsequent 24 yrs of a proffessional career in the field.

You didn't do any research before you started this thread and falsely stated: "Until 911 - Fire has never collapsed a skyscraper."

Please don't come here an insult our intelligence next time, ok?

You are violating the terms and conditions. The whole purpose of your reply was to insult him about doing "no" research when what you really mean is you disagree with his research and then you accuse him of insulting "our" intelligence.

In the future speak for yourself. He didn't insult "our" intelligence. One has to wonder about your own if you are posting so much on a thread that you feel has zero value. Why not place the user on "ignore"?

Originally posted by Watcher-In-The-Shadows
reply to post by saturnsrings

 

The very basis of your position is based on a generalized character assessment of a large group of people you have never met. And thusly almost assuredly false. Untrustworthy people are everywhere.

[edit on 22-9-2009 by Watcher-In-The-Shadows]

Yes, Watcher, untrustworthy people are everywhere, but to say that corners were cut purposefully is also making a character assessment of people that you have not met. Can you provide a link to where the builders admitted to cutting corners, or where they were taking to court for the workmanship?

The only place that I have noticed is the case and use of asbestos.

I am curious.

BTW, I'm crying right now. CRYING. WAAAAAAAHHHHHHHHHHH

reply to post by Watcher-In-The-Shadows
I would agree, except that the vast vast majority of people are honest hard working people. Could the companies that built the towers tell their workers to just do their job and keep their mouths shut? sure, but then those workers weren't paid millions to do it. Way too easy to blow the whistle. The government?



By the way...................most here never met anyone associated with the towers, that doesn't mean we can't have a opinion on the workers. As I said, imho, the towers could have been rigged with explosives rather easy with relatively few in the know. As I also stated, billions of dollars was made after 9/11. Thousands of families accepted "hush" money from the government in exchange for keeping quiet about 9/11. It may not be hush money to you, but to me, it amounts to hush money.

Have a great day.

reply to post by ChrisF231


Absolute Fabrications. Fire could not and did not "weaken the towers", and the impact of the planes was negligible.

NANOTHERMITE brought them down into their own footprint in 10 seconds.

It's a World Record. We should hand out Awards to the CIA/MOSSAD agents responsible.

And then throw them into an incinerator, alive.

It was not "shoddy construction" so much as the unknown factors in
building not one, but two of the tallest buildings at the time.

To build so high and keep it within budgets required new and untried
techniques - things like using tube framed walls, truss floor supports
instead of solid I beams, spray on fire proofing vs solid concrete/terra
cotta coating on steel beams.

Biggest problem was the spray on fire proofing - when proposed as
solution to the solid concrete masonry used previously, nobody knew
how thick to make the covering. Salesman for the product said 1/2" -
if fact never been tested, especially in something as big and complex as
WTC.

When confronted with this problem rather than incur delays and costs
to test effectiveness of the Spray on material Port Authority designers
simply went with company producing it.

Spray on Fire proofing originally made using asbestos, when asbestos was banned had to hastily reformat without asbestos. Again without testing

The Spray on Fire Proofing is very friable and will easily peel away -
tests showed later even air movements over time could dislodge it

The aircraft impacts knocked most of the fireproofing in the impact area
off the steel exposing it to fire - overheated steel began to soften and
deform until unable to support loads and gave way.

Best reference on this is "CITY IN THE SKY" by Jamie Glanz and Eric Lipton
gives complete history of WTC from inception to destruction with
emphasis on construction.

Can use google to search for and display pages to read.

reply to post by saturnsrings


Ah, so every construction worker is supposed to know how their work fits into the building as a whole? That is what foremen and engineers are for you know. I think you vastly over estimate that they would even know corners would be cut. And it HAS happend before in construction before. Here's just one example:

Hyatt Regency Walkway Collapse

Three days after the disaster, Wayne Lischka, a structural engineer hired by The Kansas City Star newspaper, discovered a significant change in the design of the walkways. Coverage of the event later earned the Star and its sister publication the Kansas City Times a Pulitzer Prize for local news reporting in 1982.[4]

The two walkways were suspended from a set of steel tie rods, with the second floor walkway hanging directly underneath the fourth floor walkway. The walkway platform was supported on 3 cross-beams suspended by steel rods retained by nuts. The cross-beams were box beams made from C-channels welded toe-to-toe. The original design by Jack D. Gillum and Associates called for three pairs of rods running from the second floor all the way to the ceiling. Investigators eventually determined that this design supported only 60 percent of the minimum load required by Kansas City building codes.[5]

Havens Steel Company, the contractor responsible for manufacturing the rods, objected to the original plan of Jack D. Gillum and Associates, since it required the whole of the rod below the fourth floor to be threaded in order to screw on the nuts to hold the fourth floor walkway in place. These threads would probably have been damaged beyond use as the structure for the fourth floor was hoisted into position. Havens therefore proposed an alternate plan in which two separate sets of tie rods would be used: one connecting the fourth floor walkway to the ceiling, and the other connecting the second floor walkway to the fourth floor walkway.[6]

This design change would prove fatal. In the original design, the beams of the fourth floor walkway had to support only the weight of the fourth floor walkway itself, with the weight of the second floor walkway supported completely by the rods. In the revised design, however, the fourth floor beams were required to support both the fourth floor walkway and the second floor walkway hanging from it. With the load on the fourth-floor beams doubled, Havens' proposed design could bear only 30 percent of the mandated minimum load.

The serious flaws of the revised design were further compounded by the fact that both designs placed the bolts directly in a welded joint between two facing C-channels, the weakest structural point in the box beams. Photographs of the wreckage show excessive deformations of the cross-section.[7] In the failure the box beams split at the weld and the nut supporting them slipped through.

Investigators concluded that the basic problem was a lack of proper communication between Jack D. Gillum and Associates and Havens Steel. In particular, the drawings prepared by Jack D. Gillum and Associates were only preliminary sketches but were interpreted by Havens as finalized drawings. Jack D. Gillum and Associates failed to review the initial design thoroughly, and accepted Havens' proposed plan without performing basic calculations that would have revealed its serious intrinsic flaws — in particular, the doubling of the load on the fourth-floor beams.

SOURCE:en.wikipedia.org...

Now it seems to me it goes to common sense that corners are most likely often cut with the idea of pocketing the cash. It's just not always it goes catastrophically wrong. But what really has me puzzled is how certain individuals will only question certain people endlessly while accepting without hesitation others.... But I recently think I figured it out.

[edit on 23-9-2009 by Watcher-In-The-Shadows]

Case in point, people that feel that either 1) the design was flawed or 2) corners were cut or both.

After the 767 jet liner crashed into the world trade center building creating the worst terror attack in history, a fire burned for 56 minutes inside the World Trade Center building number two. The top 20 floors of the building collapsed on the 90 floors below. The entire one hundred and ten-story building collapsed in 8 seconds... After a fire burned inside WTC tower number one for 102 minutes, the top 30 floors collapsed on the lower 80 floors. And the entire one hundred and ten stories of this building collapsed in 10 seconds. You can say the reason they collapsed was they were struck with a 185 ton jet airliner and the 24,000 gallons of jet fuel caused a fire of 1500 to 2000 degrees F which weakened the steel and cause the collapse. Or you can take a closer look at the buildings construction of the WTC buildings. And ask yourself why did these structures collapse so fast and so completely. The answer can be found by examining high-rise construction in New York City over the past 50 years

World Trade Center tower construction
In terms of structural system the twin towers departed completely from other high-rise buildings. Conventional skyscrapers since the 19th century have been built with a skeleton of interior supporting columns that supports the structure. Exterior walls of glass steel or synthetic material do not carry any load. The Twin towers are radically different in structural design as the exterior wall is used as the load-bearing wall. (A load bearing wall supports the weight of the floors.) The only interior columns are located in the core area, which contains the elevators. The outer wall carries the building vertical loads and provides the entire resistance to wind. The wall consists of closely spaced vertical columns (21 columns 10 feet apart) tied together by horizontal spandrel beams that girdle the tower at every floor. On the inside of the structure the floor sections consist of trusses spanning from the core to the outer wall.

Bearing walls and Open floor design
When the jet liners crashed into the towers based upon knowledge of the tower construction and high-rise firefighting experience the following happened: First the plane broke through the tubular steel-bearing wall. This started the building failure. Next the exploding, disintegrating, 185-ton jet plane slid across an open office floor area and severed many of the steel interior columns in the center core area. Plane parts also crashed through the plasterboard-enclosed stairways, cutting off the exits from the upper floors. The jet collapsed the ceilings and scraped most of the spray-on fire retarding asbestos from the steel trusses. The steel truss floor supports probably started to fail quickly from the flames and the center steel supporting columns severed by plane parts heated by the flames began to buckle, sag, warp and fail. Then the top part of the tower crashed down on the lower portion of the structure. This pancake collapse triggered the entire cascading collapse of the 110-story structure.

Steel Framing
The most noticeable change in the modern high-rise construction is a trend to using more steel and shaping lightweight steel into tubes, curves, and angles to increase its load bearing capability. The WTC has tubular steel bearing walls, fluted corrugated steel flooring and bent bar steel truss floor supports. To a modern high rise building designer steel framing is economical and concrete is a costly material. For a high-rise structural frame: columns, girders, floors and walls, steel provides greater strength per pound than concrete. Concrete is heavy. Concrete creates excessive weight in the structure of a building. Architects, designers , and builders all know if you remove concrete from a structure you have a building that weights less. So if you create a lighter building you can use columns, girders and beams of smaller dimensions, or better yet you can use the same size steel framing and build a taller structure. In News York City where space is limited you must build high. The trend over the past half-century is to create lightweight high buildings. To do this you use thin steel bent bar truss construction instead of solid steel beams. To do this you use hollow tube steel bearing walls, and curved sheet steel (corrugated) under floors. To do this you eliminate as much concrete from the structure as you can and replace it with steel. Lightweight construction means economy. It means building more with less. If you reduce the structure’s mass you can build cheaper and builder higher. Unfortunately unprotected steel warps, melts, sags and collapses when heated to normal fire temperatures about 1100 to 1200 degrees F.

The fire service believes there is a direct relation of fire resistance to mass of structure. The more mass the more fire resistance. The best fire resistive building in America is a concrete structure. The structures that limit and confine fires best, and suffer fewer collapses are reinforced concrete pre WWII buildings such as housing projects and older high rise buildings like the empire state building, The more concrete, the more fire resistance; and the more concrete the less probability of total collapse. The evolution of high- rise construction can be seen, by comparing the empire state building to the WTC. My estimate is the ratio of concrete to steel in the empire state building is 60/40. The ratio of concrete to steel in the WTC is 40/60. The tallest building in the world, the Petronas Towers, in Kula Lumpur, Malaysia, is more like the concrete to steel ratio of the empire state building than concrete to steel ratio of the WTC. Donald Trump in New York City has constructed the tallest reinforced concrete high-rise residence building.

Effects of jet crash and fire on a skeleton steel high rise
A plane that only weighted 10 tons struck the Empire State Building and the high-octane gasoline fire quickly flamed out after 35 minutes. When the firefighters walked up to the 79 floor most of the fire had dissipated. The Empire State Building in my opinion, and most fire chiefs in New York City, is the most fire safe building in America. I believe it would have not collapsed like the WTC towers. I believe the Empire State Building, and for that matter any other skeleton steel building in New York City, would have withstood the impact and fire of the terrorist’s jet plane better than the WTC towers. If the jet liners struck any other skeleton steel high rise, the people on the upper floors and where the jet crashed may not have survived; there might have been local floor and exterior wall collapse. However, I believe a skeleton steel frame high rise would not suffer a cascading total pancake collapse of the lower floors in 8 and 10 seconds. Hopefully some engineer using computer calculations, can reconstruct the effects of a 767 jetliner crashing into another New York City high building. In any other high rise in New York City, I say, the floors below the crash and fire, would not collapse in such a total a cascading pancake cave-in. Most of the occupants and rescuers killed in the WTC tower collapse were on the lower floors.

The Empire State Building
Perhaps builders should take a second look at the Empire State Buildings construction. There might be something to learn when they rebuild on ground zero. The empire state building has exterior Indiana limestone exterior wall, 8 inches thick. The floors are also 8 inches thick consisting of one-inch cement over 7 inches of cinder and concrete. All columns, girders and floor beams are solid steel covered with 1 to 2 inches of brick terracotta and concrete. There is virtually no opening in the floors. And there are no air ducts of a HVAC heating cooling and venting system penetrating fire partitions, floor, and ceilings. Each floor has its own HVAC unit. The elevators and utility shafts are masonry enclosed. And for life safety there is a 4-inch brick enclosed so-called “smoke proof stairway”. This stairway is designed to allow people to leave a floor without smoke following them and filing up the stairway. This is accomplished because this smoke proof stairway has an intermediate vestibule, which contains a vent shaft. Any smoke that seeps out the occupancy is sucked up a vent shaft.

Concrete removal
Since the end of WWII builders designed most of the concrete from the modern high-rise constriction. First concrete they eliminated was the stone exterior wall. They replace them with the “curtain walls of glass, sheet steel, or plastics. This curtain wall acted as a lightweight skin to enclose the structure from the outside elements. Next the 8-inch thick concrete floors went. They were replaced with a combination of 2 or 3 inches of concrete on top of thin corrugated steel sheets. Next the masonry enclosure for stairs and elevators were replaced with several layers of sheet rock. Then the masonry smoke proof tower was eliminated in the 1968 building code. It contained too much concrete weight and took up valuable floor space. Then the solid steel beam was replace by the steel truss. And finally the concrete and brick encasement of steel columns girders and floor supports was eliminated. A lightweight spray-on coating of asbestos or mineral fiber was sprayed over the steel. This coating provided fireproofing. After asbestos was discovered hazardous vermiculite or volcanic rock ash substance was used as a spray-on coating for steel. Outside of the foundation walls and a thin 2 or 3 inches of floors surface, concrete has almost been eliminated from high-rise office building construction. If you look at the WTC rubble at ground zero you see very little concrete and lots of twisted steel.

SOURCE:vincentdunn.com...