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Rebuilding Ground Zero
OpinionJounral.Com ^ | May 12, 2007 | Steve Malanga

Posted on 05/12/2007 6:22:52 AM PDT by Wuli

Larry Silverstein began spending every morning at the World Trade Center shortly after he inked a 99-year deal to operate the complex in July 2001. The New York developer would have breakfast at Windows on the World, the restaurant on the 107th floor of the North tower, and then meet for several hours with tenants. But on the morning of Sept. 11, 2001, he was at home, dressing for a doctor's appointment his wife had made for him, instead of at his usual table at Windows. "I had said to my wife, sweetheart, cancel my doctor's appointment. I have so much to do at the Trade Center," he recalls. "She got very upset and told me I had to go. As it turns out, that saved my life."

While he was still getting ready for his doctor's appointment, Mr. Silverstein learned that the first plane hijacked by terrorists had struck the North tower. He turned on his television just in time to see the second plane fly into the South tower. No one at Windows on the World survived.

A few weeks ago, as Mr. Silverstein and I met at his headquarters on the 38th floor of 7 World Trade Center, the 52-story skyscraper that he quickly rebuilt just north of where the twin towers once stood, we could watch the reconstruction of the rest of the Trade Center site proceed. He pointed out to me the footprints of the three other office towers he is developing there and predicted with some confidence that the site, which will include a fourth skyscraper, the so-called Freedom Tower, as well as a new transportation terminal, will be completed within five years. "I just want to..........

(Excerpt) Read more at opinionjournal.com ...


TOPICS: Business/Economy; Culture/Society; Editorial; Politics/Elections
KEYWORDS: larrysilverstein
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To: Wuli

The WTC specification called for a tower to be able to stand for about one hour after taking a full-face (but accidental) strike by the most common airliner of the day, the 707.

Each tower took a strike from a much larger aircraft, the 767. The North Tower stood for 1 hour and 39 minutes, the South Tower stood for 56 minutes and 10 seconds.

The 767-200ER that hit the North Tower weighed about 360,000 pounds and was travelling about 500 miles per hour at the time of impact. The 767-300 that hit the South Tower weighed about 300,000 pounds and was also travelling at about 500 miles per hour. A fully-laden 707-320 would weigh about 25,000lbs *less* than either 767 at time of impact; empty, it’s about 30-50,000 pounds lighter.

Kinetic energy is calculated as “mass times velocity squared”. I’m sure you can do the math. Greater weight = greater energy = greater damage.

The WTC performed as advertised and the North Tower exceeded the spec by 50%, despite not having been constructed *to* spec in the sense that it was missing the fire retardants it was supposed to have in the upper portion.

Conventional construction would have collapsed immediately, as the aircraft would have breached the concrete core that holds the building up.


21 posted on 05/12/2007 9:01:46 AM PDT by Spktyr (Overwhelmingly superior firepower and the willingness to use it is the only proven peace solution.)
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To: Logophile
Apparently the mayor and other government officials feel it is their job to criticize, pressure, and excoriate a private citizen according to how he manages his own property. Where did they get that idea?

SOP for liberals.

22 posted on 05/12/2007 9:06:21 AM PDT by airborne (Duncan Hunter is the only real choice for honest to goodness conservatives!)
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To: carton253

Sorry, but among engineers it is not useless speculation.

The WTC towers were not designed and built in the manner that most high-rise buildings were built before or have been since, and those innovations meant that the structural integrity of the building was dependent on fewer points of possible failure.

Most all high-rise buildings are built with multiple series of vertical columns from the outermost columns at the external wall, all the way in to the core. The load of the floors is then spread across all those vertical columns. Not the WTC twin towers.

The twin towers construction was unique, when built and now.

The primary vertical structure consisted only of the core and the set of vertical columns around the perimeter at the external wall, without a lot intervening columns in the space between. This provided for expansive open floors, which office space planners and rental agents loved.

In order to account for the limited vertical support, three things were done. The core was made larger and stronger. The single series of columns forming the perimeter external wall were made with a specialty steel, manufactured in Japan for those columns in particular; for the greater strength they would need. And, the horizontal structure used trusses, instead of single beams, to carry, balance and connect the load between the two primary vertical support systems - the core and the external wall.

In a normal building, if a horizontal beam under a floor failed at the point of its connection with the vertical column at the external wall, the support of its load would be shifted to the many other vertical columns, between that external wall and the core, and to the interior vertical columns to both sides of the line between the external break point and the core. But, the WTC had no such intervening columns.

And, where did the WTC structural failure begin? It began at the point of too many stressed, superheated and damaged connections of those horizontal trusses to the vertical columns forming the external wall - leaving too much of the weight attempting to simply hang off the core like limbs hanging on the tree - which it was not designed to do.

Of course no one anticipated that any fire alone would cause the integrity of the external-wall horizontal truss connection system to fail on such a scale. And no building fire alone would have caused that failure. But, the damage from the aircraft slamming into the structure and the jet-fuel-fed fire produced the unanticipated.

Yet, because of that failure, no one is again going to build a high-rise in the same manner as the WTC was built. No one is going to build a high-rise without the many intervening vertical columns, between the core and the external wall. The fewer structural elements involved also meant that fewer were needed to fail for that failure to be compounded.

This is not to “blame” those construction innovations, but from an engineering perspective, they (because of what happened on 9/11) are not innovations anyone will repeat.


23 posted on 05/12/2007 9:48:40 AM PDT by Wuli
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To: Wuli
What brought down the towers? Again - two planes and tons of jet fuel.

The rest is nothing else but fodder for many articles to be discussed ad naseum among engineers.

Unless you are posting for the thread in general, you can spare yourself time and energy by not posting your many explanations to me. I don't care. I'm not an engineer. I am a Middle East Historian.

For me... it is about Militant Islam and their desire to see our civilization destroyed... not structural this and structural that. Your many reasons dilute the issue at hand.

24 posted on 05/12/2007 9:57:50 AM PDT by carton253 (I've cried tears and stayed the same.)
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To: Wuli

Someone should call him. Quite a story.


25 posted on 05/12/2007 10:01:11 AM PDT by RobbyS ( CHIRHO)
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To: Wuli

BTTT


26 posted on 05/12/2007 10:03:59 AM PDT by Fiddlstix (Warning! This Is A Subliminal Tagline! Read it at your own risk!(Presented by TagLines R US))
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To: Spktyr

“Conventional construction would have collapsed immediately, as the aircraft would have breached the concrete core that holds the building up.”

Sorry, but it is not, is never the “concrete core that holds the building up” in a conventional high-rise. It is an element, but only one.

The vertical steel columns are set down into the bedrock - not just cemented in, but down to the bedrock. The lattice of horizontal beams tie the multiple series of vertical columns together. And, yes, the horizontal members are tied to the core as well. But, it is called the core not for its core strength, but because it is at the center of the building. The totality of the many series of vertical columns sunk to bedrock are every bit a part of the structural integrity of the building as the core.

And, because of the multiple series of columns in most high-rise buildings, you could breach the core at some upper level and that breach alone, because of the multiple points of vertical support, would not necessarily cause the building to come down. You have needlessly over-emphasized the functionality of the “core” as more independent to the structural integrity than it is, at upper levels.


27 posted on 05/12/2007 10:08:12 AM PDT by Wuli
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To: patton
Has anybody written a book about this yet?

There has been plenty of time. Hollywood could be filming the third sequel to the movie by now.

28 posted on 05/12/2007 10:10:03 AM PDT by RightWhale (Repeal the Treaty)
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To: Spktyr

While the 767 is heavier than the 707, the major difference was speed. Normal speeds at low altitude are 200 or less, FAA speed limit is 250 knots below 10,000’, so 500+, even from a 707, was WAY more kinetic energy than the specs could resist.


29 posted on 05/12/2007 10:25:57 AM PDT by diogenes ghost
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To: ALOHA RONNIE

First, he did not predict 9/11 and 2nd he has no clue of who we are really fighting and why.

He would have you believe that Osama bin Laden and his ilk are upset with the “west” because we buy their oil and they, the Suadi leaders, get rich off of our buying their oil. That idea is just plain ignorance and particularly ignorant of Islamic fundamentalists, how they think and why they think the way they do.

He was no prophet, in any sense, and he certainly was not the first or the most astute at recognizing terrorism as the warfare form of our opponents in the future.

The whole promotion of this “prophet” comes from the “war for oil” nuts.

Get your tin foil hats out.


30 posted on 05/12/2007 10:28:10 AM PDT by Wuli
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To: ALOHA RONNIE; All

First, he did not predict 9/11 and 2nd he has no clue of who we are really fighting and why.

He would have you believe that Osama bin Laden and his ilk are upset with the “west” because we buy their oil and they, the Suadi leaders, get rich off of our buying their oil. That idea is just plain ignorance and particularly ignorant of Islamic fundamentalists, how they think and why they think the way they do.

He was no prophet, in any sense, and he certainly was not the first or the most astute at recognizing terrorism as the warfare form of our opponents in the future.

The whole promotion of this “prophet” comes from the “war for oil” nuts.

Get your tin foil hats out.


31 posted on 05/12/2007 10:28:18 AM PDT by Wuli
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To: carton253

“Your many reasons dilute the issue at hand.”

It didn’t dilute the issue at hand to Osama - a civil engineer himself whose first career was in his father’s construction company helping that company build every major government construction project in Saudi Arabia, it’s roads, airports, dams, bridges, high-rises and military bases. The same engineering and construction firm run by Osama’s siblings today.


32 posted on 05/12/2007 10:34:36 AM PDT by Wuli
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To: Wuli

Fine... you win the argument. Do you feel better now?


33 posted on 05/12/2007 10:35:29 AM PDT by carton253 (I've cried tears and stayed the same.)
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To: carton253

No.


34 posted on 05/12/2007 10:37:39 AM PDT by Wuli
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To: diogenes ghost
Normal speeds at low altitude are 200 or less, FAA speed limit is 250 knots below 10,000’, so 500+, even from a 707, was WAY more kinetic energy than the specs could resist.

Exactly. The specs envisioned an accidental hit.

35 posted on 05/12/2007 10:47:38 AM PDT by Mr. Jeeves ("Wise men don't need to debate; men who need to debate are not wise." -- Tao Te Ching)
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To: Wuli; All

.

In the mid-1980’s my fellow Battle of IA DRANG-1965 Veteran RICK RESCORLA became 1st Vice-President of Security for Tower II tenant Morgan Stanley Brokerage House’s 30 middle floors, the World Trade Center’s largest tenant.

RICK RESCORLA immediatley told the NY Port Authority that they would be hit with explosives in the basement by Muslim Fundamentalist extremists. He was told to mind his own business, which he promptly did by training his 3,000 employees to quickly evacuate after a coming terrorist attack.

During the 1993 terrorist bombing attack in the World Trade Center basement, he became famously known as ‘The Last Man Out’ for his making sure everyone else got outta there first on that Day of Infamy. After which he predicted a Terrorist Attack from the Air. Getting the same response he had previously received from the Port Authority.

In 1999 CBS Television aired a TV Interview of RICK RESCORLA, taped in his own World Trade Center office with Tower I standing in the background. A TV Interview in which he predicted his own future demise at the hands of Muslim Fundamentalist extremists.

To win at war, one must first know one’s Enemy. RICK RESCORLA was predicting who that Enemy was going to be in our next World War.

It’s all a matter of recorded History.

http://www.lzxray.com

.


36 posted on 05/12/2007 11:45:08 AM PDT by ALOHA RONNIE ("ALOHA RONNIE" Guyer/Veteran-"WE WERE SOLDIERS" Battle of IA DRANG-1965 http://www.lzxray.com)
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To: Wuli

fascinating stuff - thanks.


37 posted on 05/12/2007 11:48:35 AM PDT by patton (19yrs ... only 4,981yrs to go ;))
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To: Wuli
But, had it been built in the conventional manner that almost all high-rise steel-and-concrete buildings are constructed (which it wasn’t), I doubt that it would have collapsed from the terrorist attack on it - greatly damaged, yes, but not collapsed.

The Empire State Building was hit by a much smaller airplane; the body of the plane hit at floor level, where the building was strongest, and yet still did considerable damage. Someone who was deliberate aiming a 767 to produce maximum damage could probably have caused the Empire State Building to topple instantly.

Most skyscrapers are supported by a moderate number of columns. The columns are designed for one primary purpose only: to carry vertical loads straight down to the foundation. Buildings have some ability to handle broad lateral loading (such as that produced by wind) by using the floors to shift such loads to shear walls, but the columns themselves are not designed to handle lateral loads, much less concentrated ones. They're not going to withstand a 767 hit.

Unlike the WTC, whose walls had a substantial ability to carry loads upward and diagonally downward (so that the areas above the crash site remained supported), most buildings have essentially zero ability to shift loads. Knocking out even one column can have a major impact on a building; it will usually stand, but often be damaged to the point of being permanently uninhabitable. Knocking out two or more columns will be even worse.

38 posted on 05/12/2007 4:33:05 PM PDT by supercat (Sony delenda est.)
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To: Wuli
In a normal building, if a horizontal beam under a floor failed at the point of its connection with the vertical column at the external wall, the support of its load would be shifted to the many other vertical columns, between that external wall and the core, and to the interior vertical columns to both sides of the line between the external break point and the core. But, the WTC had no such intervening columns.

Via what mechanism is such load-sharing supposed to take place? A typical building may be roughly modeled as a cubic lattice with some added diagonal struts (let's assume the primary struts run n/s, e/w, and u/d). The floor construction is highly resistant to tension and compression in the ne-sw and nw-se directions, since people generally don't mind floors that are solid. The number of struts or equivalent running in vertical-diagonal directions, however, is much smaller. While it would probably be possible to construct a building where the space of every tenth "floor" was largely obstructed by diagonal supports, and such a building would be capable of withstanding considerable structural damage without collapse, I'm unaware of such construction being anything even remotely resembling common practice.

39 posted on 05/12/2007 4:51:09 PM PDT by supercat (Sony delenda est.)
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To: Mr. Jeeves
Exactly. The specs envisioned an accidental hit.

Related to that is the fact that an accidental hit would most likely occur when a plane trying to land, and likely is low on fuel. If conditions are such that a pilot would be unaware of a 1000' building in front of him, the pilot isn't going to put himself in the air even remotely near such buildings unless he has no alternative. If a plane is on the ground during such conditions, it will stay there. If the plane is airborne and has enough fuel to either fly somewhere else where conditions might be better, or else circle at higher elevations while waiting for conditions to improve, the pilot would likely choose one of those options. Landing in dangerous conditions is generally only attempted for lack of a better alternative (although one may defer landing for awhile, "not landing" isn't really a choice).

40 posted on 05/12/2007 5:01:22 PM PDT by supercat (Sony delenda est.)
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