Did they throw away the locked doors from the Triangle Shirtwaist Fire? Did they throw away the gas can used at the Happyland Social Club Fire? Did they cast aside the pressure-regulating valves at the Meridian Plaza Fire? Of course not. But essentially, that's what they're doing at the World Trade Center.
For more than three months, structural steel from the World Trade Center has been and continues to be cut up and sold for scrap. Crucial evidence that could answer many questions about high-rise building design practices and performance under fire conditions is on the slow boat to China, perhaps never to be seen again in America until you buy your next foreign car.
Twin Towers’ Designers Anticipated Jet Impacts Like September 11
Structural engineers who designed the Twin Towers carried out studies in the mid-1960s to determine how the buildings would fare if hit by large jetliners. In all cases the studies concluded that the Towers would survive the impacts and fires caused by the jetliners.
“We looked at every possible thing we could think of that could happen to the buildings, even to the extent of an airplane hitting the side… Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed. [But] the building structure would still be there.” ~Lead WTC Structural Engineer John Skilling — The Seattle Times: (1993)
“The building was designed to have a fully loaded 707 crash into it. That was the largest plane at the time. I believe that the building probably could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door—this intense grid—and the jet plane is just a pencil puncturing that screen netting. It really does nothing to the screen netting.” ~Frank A. Demartini, the on-site construction manager for the World Trade Center — (January 25, 2001)
By Kevin Ryan | Dec 9, 2013 | Featured, US, Viewpoints | 159 |
The evidence for the presence of thermite at the World Trade Center (WTC) on 9/11 is extensive and compelling. This evidence has accumulated to the point at which we can say that WTC thermite is no longer a hypothesis, it is a tested and proven theory. Therefore it is not easy to debunk it. But the way to do so is not difficult to understand.
To debunk the thermite theory, one must first understand the evidence for it and then show how all of that evidence is either mistaken or explained by other phenomena. Here are the top ten categories of evidence for thermite at the WTC.
Molten metal: There are numerous photographs and eyewitness testimonies to the presence of molten metal at the WTC, both in the buildings and in the rubble. No legitimate explanation has been provided for this evidence other than the exothermic reaction of thermite, which generates the temperatures required and molten iron as a product.
The fires at Ground Zero could not be put out for several months. Despite the application of millions of gallons of water to the pile, several rainfall events at the site, and the use of a chemical fire suppressant, the fires would not subside. Thermal images made by satellite showed that the temperatures in the pile were far above that expected in the debris from a typical structure fire. Only thermite, which contains its own oxidant and therefore cannot be extinguished by smothering it, can explain this evidence.
Numerous eyewitnesses who were fleeing the area described the air mass as a hot wind filled with burning particles.[1] This evidence agrees with the presence of large quantities of thermite byproducts in the air, including hot metallic microspheres and still-reacting agglomerates of thermite.
Numerous vehicles were scorched or set on fire in the area. Photographic evidence shows that cars parked within the lower-level garage areas of the WTC complex burned as if impacted by a super-hot wind like that described by the eyewitnesses. All non-metallic parts of the cars, including the plastic, rubber, and glass, were completely burned off by a hot blast.
There was a distinct “white smoke” present—clearly different from smoke caused by a normal structural fire—as indicated by eyewitnesses and photographic evidence.[2]The second major product of the thermite reaction is aluminum oxide, which is emitted as a white solid shortly after reaction.
Peer-reviewed, scientific research confirmed the presence of extremely high temperatures at the WTC. The high temperatures were evidenced by metallic and other microspheres, along with evaporated metals and silicates. These findings were confirmed by 9/11 investigators and by scientists at an independent company and at the United States Geologic Survey.
The elemental composition of the metallic microspheres from the WTC dust matches that of metallic microspheres produced by the thermite reaction.
The environmental data collected at Ground Zero in the months following 9/11 indicate that violent incendiary fires, like those produced by thermite, occurred on specific dates. Peer-reviewed scientific analysis of these data show that the components of thermite spiked to extraordinary levels on specific dates in both the air and aerosol emissions at Ground Zero.
Carbon nanotubes have been found in the WTC dust and in the lungs of 9/11 first responders. Formation of carbon nanotubes requires extremely high temperatures, specific metal catalysts, and carbon compounds exactly like those found in nanothermite formulations. Researchers have discovered that nanothermite produces the same kinds of carbon nanotubes. That finding has been confirmed by independent analysis in a commercial contract laboratory.
A peer-reviewed scientific publication has identified the presence of nanothermite in the WTC dust. One of the critical aspects of that paper has been confirmed by an independent scientist.
There is also a great deal of indirect evidence for the thermite theory. This includes the attempts by NIST to downplay the evidence for thermite. It also includes things like a weak effort by Rupert Murdoch’s National Geographic Channel to discredit the ability of thermite to cut structural steel, which was itself roundly discredited by one independent investigator. It is now unquestionable that thermite can cut structural steel as needed for a demolition.
Therefore, debunking the WTC thermite theory is not easy but is very straightforward. Doing so simply requires addressing the evidence listed above point by point, and showing in each case how an alternative hypothesis can explain that evidence better. Given the scientific grounding of the thermite theory, use of the scientific method, including experiments and peer-reviewed publications, would be essential to any such debunking effort.
The test methods described in this fire-test-response standard are applicable to assemblies of masonry units and to composite assemblies of structural materials for buildings, including bearing and other walls and partitions, columns, girders, beams, slabs, and composite slab and beam assemblies for floors and roofs. They are also applicable to other assemblies and structural units that constitute permanent integral parts of a finished building..
e119.2000/astm.e119.2000_djvu.txt
Click to access walls_astm.e119.2000.pdf
As for floor assemblies, those who have been following the NIST investigation, and various explanations, know that the current claim is that the floor assemblies used in the WTC were never tested for fire resistance. But the May 2003 NIST report says that, in 1970, UL actually tested a floor assembly that was “similar to the WTC floor system”. It is important to note that the results produced in 1970 were the same as those from the August 2004 UL floor tests – only 3 inches of sagging after 120 minutes in the furnace.
In this 2003 progress report, NIST goes on to say that they intended to perform fire resistance tests not only on the floor models, as part of the WTC investigation, but also on “individual steel members”. The latter results were never reported, and no reason was ever given. But this progress report, like NIST‘s final report, focuses more on the floor assembly fire resistance, and conspicuously fails to mention the originally required fire resistance tests on steel assemblies or where these tests were performed.
UL’s second claim
Statement number two above is clearly false for several reasons. First, UL is known to be one of the few important organizations supporting codes and specifications because they “produce a Fire Resistance Index with hourly ratings for beams, columns, floors, roofs, walls and partitions tested in accordance with ASTM Standard E119.” [5]
In fact, even today you can go to UL‘s website and order fire-resistance testing for building components such as “floors, roofs, walls, beams and columns.” [6]
Additionally, the WTC report from the Federal Emergency Management Administration (FEMA) said “the UL Fire Resistance Directory …is the major reference used by architects and engineers to select designs that meet the building code requirements for fire resistance ratings.” [7]
Not only that, a New York Times article about the WTC reported in April 8, 2002 that “a furnace procedure called ASTM E-119” is used to “determine if building materials will survive out-of-control blazes.” The Times went on to report “The furnace tests, conducted at places like Underwriters Laboratories here, focus on the ability of separate building components — a steel column or a concrete roof support — to survive temperatures as high as 2,000 degrees.”
This article was critical of the tests performed as they related to the WTC, but certainly didn’t deny that they were performed, and made it clear who it was that performed them by saying –“At the Underwriters Laboratory campus in this northern Chicago suburb, where workers carry out those blazing tests…”. [8]
Research indicates that even if a steel-framed building were subjected to an impossible superfire, hundreds of degrees hotter and far more extensive then any fire ever observed in a real building, it would still not collapse. Appendix A of The World Trade Center Building Performance Study [FEMA 20012] contains the following:
“In the mid-1990s British Steel and the Building Research Establishment performed a series of six experiments at Cardington to investigate the behavior of steel-framed buildings. These experiments were conducted in a simulated, eight-story building. Secondary steel beams were not protected. Despite the temperature of the steel beams reaching 800-900 C (1,500-1,700 F) in three of the tests (well above the traditionally assumed critical temperature of 600 C (1,100 F), no collapse was observed in any of the six experiments).
In building fires outside of such laboratory experiments, steel beams and columns probably never exceed 500º C. In extensive fire tests of steel frame carparks conducted by Corus Construction in several countries, measured temperatures of the steel columns and beams, including in uninsulated structures, never exceeded 360ºC.[3]”
Click to access MultistoreySteelFramedBuildings.pdf
Twin Towers’ Designers Anticipated Jet Impacts Like September 11
Structural engineers who designed the Twin Towers carried out studies in the mid-1960s to determine how the buildings would fare if hit by large jetliners. In all cases the studies concluded that the Towers would survive the impacts and fires caused by the jetliners.
“We looked at every possible thing we could think of that could happen to the buildings, even to the extent of an airplane hitting the side… Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed. [But] the building structure would still be there.”~Lead WTC Structural Engineer John Skilling — The Seattle Times: (1993)
“The building was designed to have a fully loaded 707 crash into it. That was the largest plane at the time. I believe that the building probably could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door—this intense grid—and the jet plane is just a pencil puncturing that screen netting. It really does nothing to the screen netting.”~Frank A. Demartini, the on-site construction manager for the World Trade Center — (January 25, 2001)
The first major structural subsystem was the exterior framing, which was a vertical square tube that consisted of 236 narrow columns, 59 on each face from the 10th floor to the 107th floor (Figure 3). There were fewer, wider-spaced columns below the 7th floor to accommodate doorways. There were also columns on alternate stories at each of the beveled corners, but these did not carry gravity loads. Each column on floor 10 to 107 was fabricated by welding four steel plates to form a tall box, nominally 0.36 m (14 in) on a side. The space between the steel columns was 0.66 m (26 in), with a framed plate glass window in each gap.
Adjacent columns were connected at each floor by steel spandrel plates, 1.3 m (52 in) high. The upper parts of the buildings had less wind load and building mass to support. Thus, on higher floors, the thickness of the steel plates making up the columns decreased, becoming as thin as 6 mm (¼ in) near the top down from as thick as 76 mm (3 in) at the lower floors. There were 10 grades of steel used for the columns and spandrels, with yield strengths ranging from 248 MPa (36 ksi) to 690 MPa (100 ksi). The grade of steel used in each location was dictated by the calculated stresses due to the gravity and wind loads. All the exterior columns and spandrels were prefabricated into welded panels, three stories tall and three columns wide. The panels, each numbered to identify its location in the tower, were then bolted to adjacent units to form the walls (Figure 4). Field panels were staggered so that every third panel was spliced at each floor level. The use of identically shaped prefabricated elements was an innovation that enabled rapid construction. (pg.7)
The second structural subsystem was a central service area, or core (Figure 3), measuring approximately 41 m by 26.5 m (135 ft by 87 ft), that extended virtually the full height of the building. The long axis of the core in WTC 1 was oriented in the east-west direction, while the long axis of the core in WTC 2 was oriented in the north-south direction. The 47 columns in this rectangular space were fabricated using primarily 248 MPa (36 ksi) and 290 MPa (42 ksi) steels and decreased in size at the higher stories. The four massive corner columns bore nearly one-fifth of the total gravity load on the core columns. The core columns were interconnected by a grid of conventional steel beams to support the core floors. (pg. 7&8)
Two types of concrete were used for the floors of the WTC towers: lightweight concrete in the tenant office areas and normal weight concrete in the core area and in the mechanical areas. Because of differences in composition and weight, the two types of concrete respond differently to elevated temperatures. While their tensile strengths degrade identically, lightweight concrete retains more of its compressive strength at higher temperatures.
The specified design strength for lightweight concrete was 20.7 MPa (3 ksi) and either 20.7 MPa (3 ksi) or 27.6 MPa (4 ksi) for normal-weight concrete, depending upon the floor location within the buildings. The actual strength of concrete at room temperature is greater than that measured from cylinders poured for testing during construction, referred to as 28-day cylinder strength, as concrete continues to strengthen with age. Methods for estimating changes in concrete strength with age are specified by the American Concrete Institute (ACI) 209 [11]. The actual compressive strength of WTC concrete slabs was estimated to be 38 percent greater than the specified design strengths: 37.9 MPa (5.5 ksi) for 27.6 MPa (4 ksi) normal-weight concrete and 28.3 MPa (4.1 ksi) for 20.7 MPa (3 ksi ) normal-weight and lightweight concretes.
3.5. Passive Fire Protection
Building codes require that elements that support loads are to be protected to achieve a specified fire resistance rating, expressed in hours. The WTC towers were classified as Class 1B, which required the columns to have a 3 h fire endurance rating and the floor system to a have a 2 h rating when tested in accordance with ASTM E 119 [12]. To achieve these ratings, the structural steel was protected with sprayed fire-resistive material (SFRM) or rigid fire-rated gypsum panels. Since application of SFRM to floor trusses was an innovative fire protection method in the 1960s, PANYNJ arranged for demonstrations to establish its feasibility for the World Trade Center [13]. In 1969, The Port Authority directed that a 13 mm (0.5 in.) thick coating of SFRM be used to insulate the floor trusses. This was to achieve a Class 1A rating, even though the preponderance of evidence suggests that the towers were chosen to be Class 1B. NIST found no evidence of a technical basis for selection of the 13 mm (0.5 in.) thickness.
In 1995, The Port Authority performed a study to establish requirements for retrofit of sprayed insulation to the floor trusses during major alterations when tenants vacated spaces in the towers [13]. Based on design information for fire ratings of a similar, but not identical, composite floor truss system contained in the Fire Resistance Directory published by Underwriters Laboratories, Inc., the study concluded that a 38 mm (1.5 in.) thickness of sprayed mineral fiber material would provide a 2 h fire rating, consistent with the Class 1B requirements.
In 1999, the removal of existing SFRM and the application of new material to this thickness became Port Authority policy for full floors undergoing new construction and renovation. In the years between 1995 and 2001, thermal protection was upgraded on 18 floors of WTC 1, including those on which the major fires occurred on September 11, 2001, and 13 floors of WTC 2 that did not include the fire floors.
Multiple approaches were used to insulate structural elements in the core. Those core
columns located in rentable and public spaces, closets, and mechanical shafts were enclosed in
boxes of gypsum wallboard. The amount of the gypsum enclosure in contact with the column
varied depending on the location of the column within the core. SFRM was applied on those
faces that were not protected by a gypsum enclosure. The thicknesses specified in the
construction documents were 35 mm (1.375 in.) for the heavier columns and 60 mm (2.375 in.)
for the lighter columns [13]. Columns located at the elevator shafts were protected using the
I will need to see the films from around the Pentagon that the FBI ran around grabbing from anyone in the vicinity of there with security cameras, then someone will have to explain what the fuck happened to that other building, silent seven, it fell without a sound, no one alive saw or heard a thing.
$ELLING OUT THE INVESTIGATION
Did they throw away the locked doors from the Triangle Shirtwaist Fire? Did they throw away the gas can used at the Happyland Social Club Fire? Did they cast aside the pressure-regulating valves at the Meridian Plaza Fire? Of course not. But essentially, that's what they're doing at the World Trade Center.
For more than three months, structural steel from the World Trade Center has been and continues to be cut up and sold for scrap. Crucial evidence that could answer many questions about high-rise building design practices and performance under fire conditions is on the slow boat to China, perhaps never to be seen again in America until you buy your next foreign car.
https://www.fireengineering.com/fire-prevention-protection/elling-out-the-investigation/#gref
\\][//
Twin Towers’ Designers Anticipated Jet Impacts Like September 11
Structural engineers who designed the Twin Towers carried out studies in the mid-1960s to determine how the buildings would fare if hit by large jetliners. In all cases the studies concluded that the Towers would survive the impacts and fires caused by the jetliners.
“We looked at every possible thing we could think of that could happen to the buildings, even to the extent of an airplane hitting the side… Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed. [But] the building structure would still be there.” ~Lead WTC Structural Engineer John Skilling — The Seattle Times: (1993)
“The building was designed to have a fully loaded 707 crash into it. That was the largest plane at the time. I believe that the building probably could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door—this intense grid—and the jet plane is just a pencil puncturing that screen netting. It really does nothing to the screen netting.” ~Frank A. Demartini, the on-site construction manager for the World Trade Center — (January 25, 2001)
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Melting point of Carbon Steel 1425-1540°C (2597-2800°F)
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How to Debunk WTC Thermite
By Kevin Ryan | Dec 9, 2013 | Featured, US, Viewpoints | 159 |
The evidence for the presence of thermite at the World Trade Center (WTC) on 9/11 is extensive and compelling. This evidence has accumulated to the point at which we can say that WTC thermite is no longer a hypothesis, it is a tested and proven theory. Therefore it is not easy to debunk it. But the way to do so is not difficult to understand.
To debunk the thermite theory, one must first understand the evidence for it and then show how all of that evidence is either mistaken or explained by other phenomena. Here are the top ten categories of evidence for thermite at the WTC.
Molten metal: There are numerous photographs and eyewitness testimonies to the presence of molten metal at the WTC, both in the buildings and in the rubble. No legitimate explanation has been provided for this evidence other than the exothermic reaction of thermite, which generates the temperatures required and molten iron as a product.
The fires at Ground Zero could not be put out for several months. Despite the application of millions of gallons of water to the pile, several rainfall events at the site, and the use of a chemical fire suppressant, the fires would not subside. Thermal images made by satellite showed that the temperatures in the pile were far above that expected in the debris from a typical structure fire. Only thermite, which contains its own oxidant and therefore cannot be extinguished by smothering it, can explain this evidence.
Numerous eyewitnesses who were fleeing the area described the air mass as a hot wind filled with burning particles.[1] This evidence agrees with the presence of large quantities of thermite byproducts in the air, including hot metallic microspheres and still-reacting agglomerates of thermite.
Numerous vehicles were scorched or set on fire in the area. Photographic evidence shows that cars parked within the lower-level garage areas of the WTC complex burned as if impacted by a super-hot wind like that described by the eyewitnesses. All non-metallic parts of the cars, including the plastic, rubber, and glass, were completely burned off by a hot blast.
There was a distinct “white smoke” present—clearly different from smoke caused by a normal structural fire—as indicated by eyewitnesses and photographic evidence.[2]The second major product of the thermite reaction is aluminum oxide, which is emitted as a white solid shortly after reaction.
Peer-reviewed, scientific research confirmed the presence of extremely high temperatures at the WTC. The high temperatures were evidenced by metallic and other microspheres, along with evaporated metals and silicates. These findings were confirmed by 9/11 investigators and by scientists at an independent company and at the United States Geologic Survey.
The elemental composition of the metallic microspheres from the WTC dust matches that of metallic microspheres produced by the thermite reaction.
The environmental data collected at Ground Zero in the months following 9/11 indicate that violent incendiary fires, like those produced by thermite, occurred on specific dates. Peer-reviewed scientific analysis of these data show that the components of thermite spiked to extraordinary levels on specific dates in both the air and aerosol emissions at Ground Zero.
Carbon nanotubes have been found in the WTC dust and in the lungs of 9/11 first responders. Formation of carbon nanotubes requires extremely high temperatures, specific metal catalysts, and carbon compounds exactly like those found in nanothermite formulations. Researchers have discovered that nanothermite produces the same kinds of carbon nanotubes. That finding has been confirmed by independent analysis in a commercial contract laboratory.
A peer-reviewed scientific publication has identified the presence of nanothermite in the WTC dust. One of the critical aspects of that paper has been confirmed by an independent scientist.
There is also a great deal of indirect evidence for the thermite theory. This includes the attempts by NIST to downplay the evidence for thermite. It also includes things like a weak effort by Rupert Murdoch’s National Geographic Channel to discredit the ability of thermite to cut structural steel, which was itself roundly discredited by one independent investigator. It is now unquestionable that thermite can cut structural steel as needed for a demolition.
Therefore, debunking the WTC thermite theory is not easy but is very straightforward. Doing so simply requires addressing the evidence listed above point by point, and showing in each case how an alternative hypothesis can explain that evidence better. Given the scientific grounding of the thermite theory, use of the scientific method, including experiments and peer-reviewed publications, would be essential to any such debunking effort.
https://www.foreignpolicyjournal.com/2013/12/09/how-to-debunk-wtc-thermite/
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Steel Fire Tests
The test methods described in this fire-test-response standard are applicable to assemblies of masonry units and to composite assemblies of structural materials for buildings, including bearing and other walls and partitions, columns, girders, beams, slabs, and composite slab and beam assemblies for floors and roofs. They are also applicable to other assemblies and structural units that constitute permanent integral parts of a finished building..
e119.2000/astm.e119.2000_djvu.txt
Click to access walls_astm.e119.2000.pdf
As for floor assemblies, those who have been following the NIST investigation, and various explanations, know that the current claim is that the floor assemblies used in the WTC were never tested for fire resistance. But the May 2003 NIST report says that, in 1970, UL actually tested a floor assembly that was “similar to the WTC floor system”. It is important to note that the results produced in 1970 were the same as those from the August 2004 UL floor tests – only 3 inches of sagging after 120 minutes in the furnace.
In this 2003 progress report, NIST goes on to say that they intended to perform fire resistance tests not only on the floor models, as part of the WTC investigation, but also on “individual steel members”. The latter results were never reported, and no reason was ever given. But this progress report, like NIST‘s final report, focuses more on the floor assembly fire resistance, and conspicuously fails to mention the originally required fire resistance tests on steel assemblies or where these tests were performed.
UL’s second claim
Statement number two above is clearly false for several reasons. First, UL is known to be one of the few important organizations supporting codes and specifications because they “produce a Fire Resistance Index with hourly ratings for beams, columns, floors, roofs, walls and partitions tested in accordance with ASTM Standard E119.” [5]
In fact, even today you can go to UL‘s website and order fire-resistance testing for building components such as “floors, roofs, walls, beams and columns.” [6]
Additionally, the WTC report from the Federal Emergency Management Administration (FEMA) said “the UL Fire Resistance Directory …is the major reference used by architects and engineers to select designs that meet the building code requirements for fire resistance ratings.” [7]
Not only that, a New York Times article about the WTC reported in April 8, 2002 that “a furnace procedure called ASTM E-119” is used to “determine if building materials will survive out-of-control blazes.” The Times went on to report “The furnace tests, conducted at places like Underwriters Laboratories here, focus on the ability of separate building components — a steel column or a concrete roof support — to survive temperatures as high as 2,000 degrees.”
This article was critical of the tests performed as they related to the WTC, but certainly didn’t deny that they were performed, and made it clear who it was that performed them by saying –“At the Underwriters Laboratory campus in this northern Chicago suburb, where workers carry out those blazing tests…”. [8]
http://www.911truth.org/three-years-later-another-look-at-three-claims-from-ul/
Research indicates that even if a steel-framed building were subjected to an impossible superfire, hundreds of degrees hotter and far more extensive then any fire ever observed in a real building, it would still not collapse. Appendix A of The World Trade Center Building Performance Study [FEMA 20012] contains the following:
https://www.fema.gov/media-library/assets/documents/3544
“In the mid-1990s British Steel and the Building Research Establishment performed a series of six experiments at Cardington to investigate the behavior of steel-framed buildings. These experiments were conducted in a simulated, eight-story building. Secondary steel beams were not protected. Despite the temperature of the steel beams reaching 800-900 C (1,500-1,700 F) in three of the tests (well above the traditionally assumed critical temperature of 600 C (1,100 F), no collapse was observed in any of the six experiments).
In building fires outside of such laboratory experiments, steel beams and columns probably never exceed 500º C. In extensive fire tests of steel frame carparks conducted by Corus Construction in several countries, measured temperatures of the steel columns and beams, including in uninsulated structures, never exceeded 360ºC.[3]”
Click to access MultistoreySteelFramedBuildings.pdf
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Photos of WTC Towers In Construction:
https://willywhitten.wordpress.com/2018/03/04/9-11-simple-physics/
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Twin Towers’ Designers Anticipated Jet Impacts Like September 11
Structural engineers who designed the Twin Towers carried out studies in the mid-1960s to determine how the buildings would fare if hit by large jetliners. In all cases the studies concluded that the Towers would survive the impacts and fires caused by the jetliners.
“We looked at every possible thing we could think of that could happen to the buildings, even to the extent of an airplane hitting the side… Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed. [But] the building structure would still be there.”~Lead WTC Structural Engineer John Skilling — The Seattle Times: (1993)
“The building was designed to have a fully loaded 707 crash into it. That was the largest plane at the time. I believe that the building probably could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door—this intense grid—and the jet plane is just a pencil puncturing that screen netting. It really does nothing to the screen netting.”~Frank A. Demartini, the on-site construction manager for the World Trade Center — (January 25, 2001)
\\][//
The Construction of the WTC Towers 1 & 2
Exterior Framing
The first major structural subsystem was the exterior framing, which was a vertical square tube that consisted of 236 narrow columns, 59 on each face from the 10th floor to the 107th floor (Figure 3). There were fewer, wider-spaced columns below the 7th floor to accommodate doorways. There were also columns on alternate stories at each of the beveled corners, but these did not carry gravity loads. Each column on floor 10 to 107 was fabricated by welding four steel plates to form a tall box, nominally 0.36 m (14 in) on a side. The space between the steel columns was 0.66 m (26 in), with a framed plate glass window in each gap.
Adjacent columns were connected at each floor by steel spandrel plates, 1.3 m (52 in) high. The upper parts of the buildings had less wind load and building mass to support. Thus, on higher floors, the thickness of the steel plates making up the columns decreased, becoming as thin as 6 mm (¼ in) near the top down from as thick as 76 mm (3 in) at the lower floors. There were 10 grades of steel used for the columns and spandrels, with yield strengths ranging from 248 MPa (36 ksi) to 690 MPa (100 ksi). The grade of steel used in each location was dictated by the calculated stresses due to the gravity and wind loads. All the exterior columns and spandrels were prefabricated into welded panels, three stories tall and three columns wide. The panels, each numbered to identify its location in the tower, were then bolted to adjacent units to form the walls (Figure 4). Field panels were staggered so that every third panel was spliced at each floor level. The use of identically shaped prefabricated elements was an innovation that enabled rapid construction. (pg.7)
The second structural subsystem was a central service area, or core (Figure 3), measuring approximately 41 m by 26.5 m (135 ft by 87 ft), that extended virtually the full height of the building. The long axis of the core in WTC 1 was oriented in the east-west direction, while the long axis of the core in WTC 2 was oriented in the north-south direction. The 47 columns in this rectangular space were fabricated using primarily 248 MPa (36 ksi) and 290 MPa (42 ksi) steels and decreased in size at the higher stories. The four massive corner columns bore nearly one-fifth of the total gravity load on the core columns. The core columns were interconnected by a grid of conventional steel beams to support the core floors. (pg. 7&8)
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.3.4. Concrete
Two types of concrete were used for the floors of the WTC towers: lightweight concrete in the tenant office areas and normal weight concrete in the core area and in the mechanical areas. Because of differences in composition and weight, the two types of concrete respond differently to elevated temperatures. While their tensile strengths degrade identically, lightweight concrete retains more of its compressive strength at higher temperatures.
The specified design strength for lightweight concrete was 20.7 MPa (3 ksi) and either 20.7 MPa (3 ksi) or 27.6 MPa (4 ksi) for normal-weight concrete, depending upon the floor location within the buildings. The actual strength of concrete at room temperature is greater than that measured from cylinders poured for testing during construction, referred to as 28-day cylinder strength, as concrete continues to strengthen with age. Methods for estimating changes in concrete strength with age are specified by the American Concrete Institute (ACI) 209 [11]. The actual compressive strength of WTC concrete slabs was estimated to be 38 percent greater than the specified design strengths: 37.9 MPa (5.5 ksi) for 27.6 MPa (4 ksi) normal-weight concrete and 28.3 MPa (4.1 ksi) for 20.7 MPa (3 ksi ) normal-weight and lightweight concretes.
3.5. Passive Fire Protection
Building codes require that elements that support loads are to be protected to achieve a specified fire resistance rating, expressed in hours. The WTC towers were classified as Class 1B, which required the columns to have a 3 h fire endurance rating and the floor system to a have a 2 h rating when tested in accordance with ASTM E 119 [12]. To achieve these ratings, the structural steel was protected with sprayed fire-resistive material (SFRM) or rigid fire-rated gypsum panels. Since application of SFRM to floor trusses was an innovative fire protection method in the 1960s, PANYNJ arranged for demonstrations to establish its feasibility for the World Trade Center [13]. In 1969, The Port Authority directed that a 13 mm (0.5 in.) thick coating of SFRM be used to insulate the floor trusses. This was to achieve a Class 1A rating, even though the preponderance of evidence suggests that the towers were chosen to be Class 1B. NIST found no evidence of a technical basis for selection of the 13 mm (0.5 in.) thickness.
In 1995, The Port Authority performed a study to establish requirements for retrofit of sprayed insulation to the floor trusses during major alterations when tenants vacated spaces in the towers [13]. Based on design information for fire ratings of a similar, but not identical, composite floor truss system contained in the Fire Resistance Directory published by Underwriters Laboratories, Inc., the study concluded that a 38 mm (1.5 in.) thickness of sprayed mineral fiber material would provide a 2 h fire rating, consistent with the Class 1B requirements.
In 1999, the removal of existing SFRM and the application of new material to this thickness became Port Authority policy for full floors undergoing new construction and renovation. In the years between 1995 and 2001, thermal protection was upgraded on 18 floors of WTC 1, including those on which the major fires occurred on September 11, 2001, and 13 floors of WTC 2 that did not include the fire floors.
Multiple approaches were used to insulate structural elements in the core. Those core
columns located in rentable and public spaces, closets, and mechanical shafts were enclosed in
boxes of gypsum wallboard. The amount of the gypsum enclosure in contact with the column
varied depending on the location of the column within the core. SFRM was applied on those
faces that were not protected by a gypsum enclosure. The thicknesses specified in the
construction documents were 35 mm (1.375 in.) for the heavier columns and 60 mm (2.375 in.)
for the lighter columns [13]. Columns located at the elevator shafts were protected using the
same SFRM thicknesses.(pg. 18 & 19)
http://ws680.nist.gov/publication/get_pdf.cfm?pub_id=910105
http://ws680.nist.gov/publication/get_pdf
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I will need to see the films from around the Pentagon that the FBI ran around grabbing from anyone in the vicinity of there with security cameras, then someone will have to explain what the fuck happened to that other building, silent seven, it fell without a sound, no one alive saw or heard a thing.
Hi, I just discovered your comment after all this time!!!
Thank you for the comment.
Please keep reading my Substacks : New URL:
https://wwhitten.substack.com/p/petroleum-renewable-not-fossil-fuel
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The bombs were installed during the elevator upgrades that were still finishing up on 9/11 - Ace Elevator upgrades WTC.
https://www.harmreductionohio.org/wp-content/uploads/2021/09/WTC-story-page-3.pdf
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