You're a structural engineer, right? What school is your degree from? What year? What state are you licensed in? I assume you have your P.E. license and not just E.I.T. to be spouting off so.
There was molten steel in the basements of the towers which would have been impossible from a jet fuel fire.
siliconinvestor.com
siliconinvestor.com
Your hash was settled long ago.
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WTC Construction:
WTC CONSTRUCTION
[ European Journal of International Law - Discussion Forum on the Attack on the World Trade Center ] [ Forum Help ]
Posted by Lewis B. Sckolnick on August 20, 2002 at 00:47:28:
The NY/NJ Port Authority saved approx US$50million by not putting in carrying beams and vertical supports. All the buildings at the WTC had the exterior walls act as carrying beams and supports. The Port Authority saved more money by not putting in a sprinkler system at time of construction. I think the Arabs had very good knowledge that the towers would fall, the other buildings were just an extra gift. With proper construction loss of life would have been in the 400-600 range with damge to 3-4 floors of each tower. Failure to have in place aerial resucue as
Chicago does, shows a level of stupidity that is becoming the hallmark of the Decline of our Civilization.
ejil.org
emporis.com
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Construction of the World Trade Center Twin Towers
* Tower One was 1,368 feet (414 meters) tall
* Tower Two was 1,362 feet (412 meters) tall
* Each tower was 64 m square
* Each tower stood 411 m above street level
* The Towers rested on solid bedrock and the foundations extended 21 m below grade
* The Towers had a height-to-width ratio of 6.8.
* The Tower facades were constructed of aluminum and steel lattice
* Each tower used a lightweight tube construction with 244 closely spaced columns on the outer walls
* A 80 cm tall web joist connected the core to the perimeter at each floor
* Concrete slabs were poured over the web joists to form the floors
* There were no interior columns in the Tower office spaces
* Each tower contained 104 passenger elevators
* Each tower had 21,800 windows
* Each tower weighed about 500,000 tons
* About 50,000 people worked in the World Trade Center complex
architecture.about.com
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DAY OF INFAMY 2001
WTC collapse due to environmentalism?
Fire, heat weakened asbestos-free steel columns of towers
By Jon Dougherty
© 2001 WorldNetDaily.com
The collapse of the Twin Towers of the World Trade Center shortly after being struck by airliners occurred because New York City banned the use of asbestos as a fire retardant during the buildings' construction, one industry expert has alleged.
Ground-level view of the Twin Towers prior to the Sept. 11 attacks.
"The Trade Tower design – the one referred to as able to resist the crash of a Boeing 707 – specified the use of asbestos insulation on the supporting columns," said chemistry professor Art Robinson, writing in the September edition of Access to Energy, a monthly science and technology newsletter.
"This was used on all columns up to the 64th floors. Then, however, in 1971 when the Trade Center Towers were still under construction, New York City banned this use of asbestos," Robinson, who is also a founder of the Oregon Institute of Science and Medicine, said.
The institute is a small research facility founded in 1980 to conduct basic and applied research in subjects immediately applicable to improvements in human life, including biochemistry, diagnostic medicine, nutrition, preventive medicine and aging, according to organization literature.
"Asbestos was an early victim of junk science and enviro-fear propaganda," Robinson said. Environmental activists "were joined by opportunistic lawyers and businessmen who reaped large profits from the anti-asbestos program. There was not a shred of evidence that insulating buildings with asbestos was harmful to human health," he added.
According to the Environmental Protection Agency, asbestos – a mineral that first became widely used in the U.S. in the 1940s – causes different types of cancer, as well as chronic breathing problems for those routinely exposed to it.
One study found that workers exposed to asbestos who smoke are about 90 times more likely to develop lung cancer than people who neither smoke nor have been exposed to asbestos, the EPA says.
But other scientists agree with Robinson. In 1998, for example, Montreal epidemiologist Michel Camus and two colleagues, writing in the New England Journal of Medicine, said their study found "no measurable excess risk of death due to lung cancer" due to "exposure to moderate levels of asbestos. …"
The researchers analyzed the health records of thousands of women from a district in Quebec known to contain the world's largest concentration of asbestos mines and mills.
Also, in the immediate aftermath of the Twin Towers collapse, the EPA moved to calm fears, pointing out that although the North Tower contained some asbestos, New York City residents were not in danger from asbestos-related disease because, the agency explained, the mineral was harmful only if breathed at high levels and over sustained periods of time.
Heat, fire weakens towers' columns
Robinson said the Twin Towers were designed to withstand a raging four-hour fire before its steel beam infrastructure lost enough of its strength and collapsed. In the intervening time frame, experts believed that tower visitors and workers below the fire level would have ample opportunity to escape, while those trapped in floors above the fire would be plucked from the roof by helicopter.
However, Tower One collapsed one hour and 40 minutes after it was struck by the first airliner; Tower Two collapsed after 56 minutes of fire.
"Had the towers stood for four hours, an estimated 5,000 people would still be alive, and the buildings would probably still be proudly standing – with large gashes in their upper floors," Robinson said.
In making his case, Robinson quoted the designer of the asbestos steel-beam coating procedure banned in New York City during the construction of the towers.
The inventor, Herbert Levine, often said during the final phases of WTC construction in the 1970s: "If a fire breaks out above the 64th floor, that building will fall down."
Robinson pointed out that skyscrapers like the Empire State Building have their steel columns insulated with concrete – which is expensive and difficult to use.
But, "in the late 1940s, Herbert Levine invented a spray fireproofing composed of asbestos and mineral wool. This invention was instrumental in allowing the construction of large steel-framed buildings," he said.
Levine's company did not get the contract to insulate the steel beams of the Twin Towers, but he had confidence in the company that did win the contract until New York banned asbestos and forced the winning contractor to use a "jury-rigged substitute insulation."
Still, other experts believe the collapse of the buildings may have been inevitable, given the circumstances.
"The impact of aircraft of more than 100 tons, at a velocity of several hundred miles per hour, with a fire load of thousands of gallons of kerosene are not things we contemplate for our clients on a day-to-day basis," said John A. Hill, president of the UK-based Institution of Structural Engineers. He believes that a willful terrorist can always find a way to demolish any structure.
Others say the heat of the fires generated by the planes took its toll on the steel beams supporting the towers.
"It was the fire that killed the buildings – nothing on earth could survive those temperatures with that amount of fuel burning," said Chris Wise, another British structural engineer. "The columns would have melted, the floors would have melted, and eventually they would have collapsed one on top of each other."
Robinson says the jet fuel-laden fires did not generate an unusual amount of heat, instead only generating the amount of heat such fires would normally produce. The difference, he insists, was that the towers "were not properly insulated, causing them to become weak by the heat of a sustained fire."
"It's notable that Mr. Levine didn't make his comments after the attacks, but instead made them 30 years ago," Robinson told WND. "And he was the world's expert on insulating steel columns."
Robinson also said he was "certain" that had the columns been insulated with asbestos, the towers would have remained standing "long enough" for many more people to have escaped.
"Whether that means both buildings would currently still be standing, that's a question," he said. "But we wouldn't be looking at 5,000 deaths."
Ground for the towers was broken Aug. 5, 1966. The towers were opened sequentially, as floors and sections were completed, beginning in 1970. All floor space was completed and both towers were completely opened during a ribbon cutting ceremony April 4, 1973.
The Port Authority of New York and New Jersey owned the towers, as well as five other WTC-related buildings located within the complex in Lower Manhattan. Building No. 7 also collapsed the afternoon of the attacks.
worldnetdaily.com
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Why the World Trade Center Buildings Collapsed
A Fire Chief ’s Assessment
By: Deputy Chief Vincent Dunn ret.
vincentdunn.com
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.
The computer designed high rise building
The computer has allowed engineers to reduce the mass of a structure by its ability to more accurately determine the load bearing capability of structural framework. Years ago before the computer, builders were not sure of a structural elements load bearing capability, so they over built by using a so called “safety factor”. This built in safety factor could result in a structure with twice the required load bearing strength. Because of computer calculation this no longer occurs. The older buildings use to have built in a so called “safety factor” of two-to-one. Not so today, if the building code requires a load bearing factor of 40 pounds per square foot that is exactly what you get. There is no margin for error.
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.
The performance building code
How did lightweight high-rise construction evolve since WWII? It evolved with the help of the so-called performance code. After WWII the builders complained about building codes. They said they were too restrictive and specified every detail of construction. They called the old building codes “specification codes”. They complained the codes specified the size and type and some times even the make of a product used in construction. They decried the specification code as old fashion. They wanted the building codes changed to what they called “performance codes.” They wanted the building codes to specify the performance requirements only; and, not specify the size and type of building material to use. For example, with fire resistive requirements they wanted the code to state just the hours of fire resistance (one, two, three or four hours) required by law; and not to state the specific type and material used to protect structural steel and enclosures for stairways and elevators shafts. For example, a performance building code states: the steel has to be protected against heat of flames for one, two, three or four hours during a fire. It does not state what to use as a fire resisting material. This performance code signaled the end to concrete encasement fire protection and allowed a spray on fire protection for steel and plasterboard enclosed stairs and elevator shafts. Builders hailed the New York City building code of 1968 as a good performance code. However, some fire chiefs decried it as a law that substituted frills for real construction safety. The asbestos spray on coating of steel trusses used in the WTC towers was considered by Chief of the New York City Fire Department, at the time, John T. O’ Hagan to be inferior to concrete encasement of steel. Writing in his book, High Rise Fire and Life Safety. l976, he listed the following problems of spray-on fire protection of steel:
1. Failure to prepare the steel for spray-on coating adhesion. Rust and dirt allowed spray-on fire retarding coating to scale and fall away from steel during construction
2. Poor or uneven application of the spray-on fire retarding was discovered during post fire investigations
3. Variation of spray-on material during manufacture makes it ineffective
4. Lack of thoroughness in covering the steel during application is a problem
5. Failure to replace spray-on material dislodged by other trades people performing work around the steel during the construction of the building.
The WTC started construction in the 1970s. And the WTC towers built by the Port Authority of New York did not have to comply with the minimum requirements of the new1968 performance building code.
Recommendations for constructing the new high rise buildings on ground zero
* The steel columns, girders and floor beams should be encased in masonry or other more effective fire retarding material. Spray-on fire retarding is ineffective. Post fire investigations reveals the spray on fire retardant has scaled off and steel beams and concrete and steel floor slabs crack and allow flame spread.
* Lightweight bar joists should not be used to support floors in high-rise buildings. The National Fire Protection Association has shown unprotected steel bar joist fail after five or ten minutes of fire exposure.
* For life safety in high-rise buildings bring back the smoke proof tower. This allows people to escape fire using smoke free stairways.
* Stairs and elevator shaft ways should be enclosed in masonry to prevent smoke spread.
* Heating ventilation and air condition HVAC systems should be provided by unit system serving only one or two floors. Central air system serving 10 or 20 floors creates shaft ways and duct systems that penetrate fire rated floors walls partitions and ceilings. Smoke spreads throughout ducts of central HVAC systems.
* The high rise building framework should be skeleton steel framing not center core steel column framing. There should be no bearing wall high rise construction. Reduce the size of open floor design.
* Increase the thickness of concrete in floor construction. The two or three inches of concrete over corrugated steel fails during most serious high rise fires and must be replaced.
* Automatic sprinklers should protect all high rise buildings. Firefighters can extinguish approximately 2,500 square foot of fire with one hose line. Two hose steams may quench 5,000 square feet of fire. The World Trade Center floor areas were 40,000 square feet in area.
* Federal, State and Port Authority buildings should comply with New York City building codes and actually in some cases should exceed them. Remember building codes are only minimum standards.
vincentdunn.com
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WTC was made up of:
Each Tower:
–200,000 tons of steel
–425,000 cubic yards of concrete
–43,600 windows
–12,000 miles of electric cables
–Had its own zip code, 10048 –Had 110 floors
–Was 50,000 sq ft (each floor)
–Weighed 500,000 tons
–Was 1,368 ft high (north tower)
–Was 1,362 ft high (south tower)
–Contained 198 miles of heating ducts
–97 elevators for passengers, 6 for freight
infoplease.com
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The World Trade Center
Height: 1,368 and 1,362 feet (417 and 415 meters)
Owners: Port Authority of New York and New Jersey
Architect: Minoru Yamasaki, Emery Roth and Sons consulting
Engineer: John Skilling and Leslie Robertson of Worthington, Skilling, Helle and Jackson
Ground Breaking: August 5, 1966
Opened: 1970-73; April 4, 1973 ribbon cutting
The World Trade Center was more than its signature twin towers: it was a complex of seven buildings on 16-acres, constructed and operated by the Port Authority of New York and New Jersey (PANYNJ). The towers, One and Two World Trade Center, rose at the heart of the complex, each climbing more than 100 feet higher than the silver mast of the Empire State Building.
Construction of a world trade facility had been under consideration since the end of WWII. In the late 1950s the Port Authority took interest in the project and in 1962 fixed its site on the west side of Lower Manhattan on a superblock bounded by Vesey, Liberty, Church and West Streets. Architect Minoru Yamasaki was selected to design the project; architects Emery Roth & Sons handled production work, and, at the request of Yamasaki, the firm of Worthington, Skilling, Helle and Jackson served as engineers.
The Port Authority envisioned a project with a total of 10 million square feet of office space. To achieve this, Yamasaki considered more than a hundred different building configurations before settling on the concept of twin towers and three lower-rise structures. Designed to be very tall to maximize the area of the plaza, the towers were initially to rise to only 80-90 stories. Only later was it decided to construct them as the world's tallest buildings, following a suggestion said to have originated with the Port Authority's public relations staff.
Yamasaki and engineers John Skilling and Les Robertson worked closely, and the relationship between the towers' design and structure was clear. Faced with the difficulties of building to unprecedented heights, the engineers employed an innovative structural model: a rigid "hollow tube" of closely spaced steel columns with floor trusses extended across to a central core. The columns, finished with a silver-colored aluminum alloy, were 18 3/4" wide and set only 22" apart, making the towers appear from afar to have no windows at all.
Also unique to the engineering design were its core and elevator system. The twin towers were the first supertall buildings designed without any masonry. Worried that the intense air pressure created by the buildingsâ high speed elevators might buckle conventional shafts, engineers designed a solution using a drywall system fixed to the reinforced steel core. For the elevators, to serve 110 stories with a traditional configuration would have required half the area of the lower stories be used for shaftways. Otis Elevators developed an express and local system, whereby passengers would change at "sky lobbies" on the 44th and 78th floors, halving the number of shaftways.
Construction began in 1966 and cost an estimated $1.5 billion. One World Trade Center was ready for its first tenants in late 1970, though the upper stories were not completed until 1972; Two World Trade Center was finished in 1973. Excavation to bedrock 70 feet below produced the material for the Battery Park City landfill project in the Hudson River. When complete, the Center met with mixed reviews, but at 1,368 and 1,362 feet and 110 stories each, the twin towers were the world's tallest, and largest, buildings until the Sears Tower surpassed them both in 1974.
skyscraper.org
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WTC 7:
whatreallyhappened.com |
