- Thread starter
- #81
World Trade Center's North Tower on Sept. 11, 2001.
- Thread starter Mr.Fitnah
- Start date
computer animations are not cartoon you fucking idiot
eots
no fly list
computer simulations are all the evidence NIST has
liar
computer simulations are all the evidence NIST has
- Thread starter
- #86
computer simulations are all the evidence NIST has
Im waiting for you to say what happens to the floor joist when subject to the uneven heating .
Then we can go onto the evidence.
eots
no fly list
Or look at the evidence .
computer simulations are all the evidence NIST has
Im waiting for you to say what happens to the floor joist when subject to the uneven heating .
Then we can go onto the evidence.
I gave you the only answer ...proper floor model test with actual temperatures present would be required to know with certainty...why what is your theorized result ?
- Thread starter
- #88
You are going to be doing the proving here Im just guiding the proof.
You made claims about uneven heating doing something, what does it do?
i guess Id-Eots wants they to rebuild the towers and then do it again
eots
no fly list
I said proper floor model ..is that concept beyond your limited thinking ?
but if they did that, you would claim it wasnt done right
so why bother for a few numbnutz like you
- Thread starter
- #92
Mr. eots since you cannot think for yourself perhaps you can glean what would happen the the floor joist if you were to read NIST NCSTAR 1-6 chapter 8.6 page 278 onward until you figure out what it was you were trying to say.
SFC Ollie
Still Marching
Not difficult to see the inward bow of the building and realize why....It certainly isn't because bombs are going to go off.
eots
no fly list
guiding the proof...lol what a dork...the question has been well answered by me but you seem afraid to offer your opinion ..the only facts I can give is the temperatures required for failure are not verified in any forensic testing of salvage material and floor model test were not done..in favour of very questionable computer simulations...the NIST report fails to determine the cause of the collapse and an independent fact driven investigation is required...these are facts...despite the extremely high probability of explosives being the cause of the collapse it remains.. "theory"
- Thread starter
- #96
Frank Gayle
Position
Deputy Chief of the Metallurgy Division
Material Science and Engineering Laboratory
Task
Forensic Analysis of Structural Steel
Education
Massachusetts Institute of Technology (1985), Ph.D., Metallurgy
Dr. Frank W. Gayle is leading the team of experts addressing the steel forensics aspects of NIST's investigation of the World Trade Center collapses. His team is evaluating steel recovered from the WTC site to determine its quality, mechanical properties, and behavior under impact and high temperature conditions.
Dr. Gayle currently serves as Deputy Chief of the Metallurgy Division in the NIST Materials Science and Engineering Laboratory and as Group Leader for the Division's Materials Structure and Characterization Group. His work at NIST has covered a range of metallurgical research addressing metals characterization and structure-property relationships. He holds several patents and has published over 50 archival research articles.
Dr. Gayle holds a Doctor of Science degree in Metallurgy from the Massachusetts Institute of Technology (1985). He also earned a Bachelor of Science in Civil Engineering (1975) and a Master of Science in Materials Science (1976) from Duke University. Dr. Gayle spent 11 years in industry at Pratt & Whitney Aircraft and Reynolds Metals Company in the field of alloy development for aerospace applications prior to coming to NIST.
Position
Deputy Chief of the Metallurgy Division
Material Science and Engineering Laboratory
Task
Forensic Analysis of Structural Steel
Education
Massachusetts Institute of Technology (1985), Ph.D., Metallurgy
Dr. Frank W. Gayle is leading the team of experts addressing the steel forensics aspects of NIST's investigation of the World Trade Center collapses. His team is evaluating steel recovered from the WTC site to determine its quality, mechanical properties, and behavior under impact and high temperature conditions.
Dr. Gayle currently serves as Deputy Chief of the Metallurgy Division in the NIST Materials Science and Engineering Laboratory and as Group Leader for the Division's Materials Structure and Characterization Group. His work at NIST has covered a range of metallurgical research addressing metals characterization and structure-property relationships. He holds several patents and has published over 50 archival research articles.
Dr. Gayle holds a Doctor of Science degree in Metallurgy from the Massachusetts Institute of Technology (1985). He also earned a Bachelor of Science in Civil Engineering (1975) and a Master of Science in Materials Science (1976) from Duke University. Dr. Gayle spent 11 years in industry at Pratt & Whitney Aircraft and Reynolds Metals Company in the field of alloy development for aerospace applications prior to coming to NIST.
- Thread starter
- #99
My opinion is not required
THE FAILURE OF THE TOWERS
At 8:46:30 the first airplane struck the north wall of World Trade Center (WTC) 1 between floors 93 and 98. About 15% of the jet fuel burned in the fireball outside the building. Another 15% burned inside the building immediately.
The rest fueled the fires that started. The overpressure from the fireball blew out many of the windows, which subsequently provided oxygen for fires. The impact damaged or severed 38 of 59 exterior columns on the north wall, and, based on the aircraft impact analysis, 9 of the 47 core columns.
The passage of the impact debris through the tower stripped the insulation from columns and floor trusses on the impact floors. Over the next 102 min., the fires moved from the north (impact) side to the south side. Eighty minutes after impact, the south wall began to bow inward. At 97 min., it reached its maximum observed displacement of 1.4 m. Just before collapse, the building section above the impact zone tilted to the south, and at 10:28:25, 102 min. after impact, WTC 1 began to collapse.
The second airplane struck the south wall of WTC 2 at 9:02:59 between floors 78 and 84. The effects of the fireball were similar to those in WTC 1. The impact damaged 32 of 59 exterior wall columns, and based on the aircraft impact analysis, 11 of 47 core columns. As in WTC 1, the passage of the impact debris stripped insulation from columns and fl oor trusses.
Unlike WTC 1, the fire moved quickly to the east side of the building, but then remained there. Within ten minutes of impact, the east wall began to bow inward. Just before collapse, the building section above the impact zone tilted to the east and south, and at 9:58:59, 56 minutes after impact, WTC 2 began to collapse.
THE FAILURE OF THE TOWERS
At 8:46:30 the first airplane struck the north wall of World Trade Center (WTC) 1 between floors 93 and 98. About 15% of the jet fuel burned in the fireball outside the building. Another 15% burned inside the building immediately.
The rest fueled the fires that started. The overpressure from the fireball blew out many of the windows, which subsequently provided oxygen for fires. The impact damaged or severed 38 of 59 exterior columns on the north wall, and, based on the aircraft impact analysis, 9 of the 47 core columns.
The passage of the impact debris through the tower stripped the insulation from columns and floor trusses on the impact floors. Over the next 102 min., the fires moved from the north (impact) side to the south side. Eighty minutes after impact, the south wall began to bow inward. At 97 min., it reached its maximum observed displacement of 1.4 m. Just before collapse, the building section above the impact zone tilted to the south, and at 10:28:25, 102 min. after impact, WTC 1 began to collapse.
The second airplane struck the south wall of WTC 2 at 9:02:59 between floors 78 and 84. The effects of the fireball were similar to those in WTC 1. The impact damaged 32 of 59 exterior wall columns, and based on the aircraft impact analysis, 11 of 47 core columns. As in WTC 1, the passage of the impact debris stripped insulation from columns and fl oor trusses.
Unlike WTC 1, the fire moved quickly to the east side of the building, but then remained there. Within ten minutes of impact, the east wall began to bow inward. Just before collapse, the building section above the impact zone tilted to the east and south, and at 9:58:59, 56 minutes after impact, WTC 2 began to collapse.
- Thread starter
- #100
The Most Probable Collapse Sequence
The investigation team integrated the photographic record, the eyewitness accounts, the experimental results, and the results of the aircraft impact analysis, fire spread and growth analysis, heat conduction analysis, and structural response analysis to determine the probable collapse sequence for each tower.
Report NIST NCSTAR 1-6, from which this summary is abstracted, summarizes the observations, results, and findings in much greater detail.
The sequences of events leading to collapse initiation were similar, but not identical, for each tower. Four major structural events were common to both sequences. First, the floors that lost insulation due to debris impact sagged as the truss members deformed and buckled under elevated steel temperature. The sagging floors pulled inward at the column connections and caused the exterior wall to bow inward.
Next, the exterior wall bowed and plastically buckled under the combined effects of the reduced strength at elevated temperatures, increased axial loads redistributed from the severed columns, pull-in forces from sagging floors, and loss of lateral support due to failure of truss seat connections. Then, the core columns weakened under the combined effects of structural impact damage, reduced elevated temperature strength, and plastic buckling of core columns.
In addition, the loads on the remaining core columns increased as gravity loads redistributed from the damaged core columns. Finally, the gravity loads redistributed because of the impact damage, restrained thermal expansion, weakening of the core, leaning of the section above the impact damage, and bowing and buckling of exterior walls. The hat truss primarily redistributed the gravity loads from the core to the exterior walls, but the adjacent exterior walls redistributed load primarily through the spandrels. All three major subsystems—the building core, the building floors, and the exterior walls—played a role in the structural collapse sequence for WTC 1 and WTC 2.
Role of the Building Core
The core columns were designed to carry the building gravity loads and were loaded to approximately 50% of their capacity before the aircraft impact. The core columns were weakened significantly by thermal effects and by the aircraft impact damage. Thermal effects dominated the weakening of WTC 1.
As the fires moved from the north to the south side of the core, the WTC 1 core was weakened over time by significant creep strains on its south side. Aircraft impact damage dominated the weakening of WTC 2. Immediately after impact, the vertical displacement at the southeast corner of the WTC 2 core increased 15 cm, from 10 cm to 25 cm. With the impact damage, the core subsystem leaned to the southeast and was supported by the south and east floors and exterior walls. Gravity loads redistributed from the core to the exterior faces primarily through the hat truss due to aircraft impact and thermal effects.
The WTC 1 core carried 1% less load after impact but 20% less after thermal weakening. The WTC 2 core carried 6% less load after impact and 2% less load after thermal weakening. Additional axial loads that were redistributed to the exterior columns from the core were not significant (only about 20% to 25% on average), because the exterior columns were loaded to only approximately 20% of their capacity before the aircraft impact.
Role of the Building Floors
The floors were designed to support occupancy loads and transfer them to the core and exterior columns. They were also designed to act as horizontal diaphragms when the buildings were subject to high winds.
In the collapse of the towers, the floors provided inward pull forces as they sagged signifi cantly under thermal loads. However, the sagging floors continued to support their floor loads despite the dislodged insulation and extensive fires. Some truss seat connections with dislodged insulation at the exterior columns did fail and disconnect from the exterior wall under thermal loads. Floor disconnections increased the unsupported length of the exterior columns and distributed floor loads to adjacent truss seats. No inward pull forces existed where the floors were disconnected.
Role of Exterior Walls
Column instability over an extended region of the exterior face ultimately triggered the global system collapse, because the loads could not be redistributed through the hat truss to the already weakened building core. In the area of exterior column buckling, loads transferred through the spandrels to adjacent columns and adjacent exterior walls. As the exterior wall buckled, on the south face of WTC 1 and the east face of WTC 2, column instability propagated to adjacent faces and caused the initiation of the building collapse.
The exterior wall instability was induced by a combination of thermal weakening of the columns, inward pull forces from sagging floors, and to a much lesser degree, additional axial loads redistributed from the core.
The investigation team integrated the photographic record, the eyewitness accounts, the experimental results, and the results of the aircraft impact analysis, fire spread and growth analysis, heat conduction analysis, and structural response analysis to determine the probable collapse sequence for each tower.
Report NIST NCSTAR 1-6, from which this summary is abstracted, summarizes the observations, results, and findings in much greater detail.
The sequences of events leading to collapse initiation were similar, but not identical, for each tower. Four major structural events were common to both sequences. First, the floors that lost insulation due to debris impact sagged as the truss members deformed and buckled under elevated steel temperature. The sagging floors pulled inward at the column connections and caused the exterior wall to bow inward.
Next, the exterior wall bowed and plastically buckled under the combined effects of the reduced strength at elevated temperatures, increased axial loads redistributed from the severed columns, pull-in forces from sagging floors, and loss of lateral support due to failure of truss seat connections. Then, the core columns weakened under the combined effects of structural impact damage, reduced elevated temperature strength, and plastic buckling of core columns.
In addition, the loads on the remaining core columns increased as gravity loads redistributed from the damaged core columns. Finally, the gravity loads redistributed because of the impact damage, restrained thermal expansion, weakening of the core, leaning of the section above the impact damage, and bowing and buckling of exterior walls. The hat truss primarily redistributed the gravity loads from the core to the exterior walls, but the adjacent exterior walls redistributed load primarily through the spandrels. All three major subsystems—the building core, the building floors, and the exterior walls—played a role in the structural collapse sequence for WTC 1 and WTC 2.
Role of the Building Core
The core columns were designed to carry the building gravity loads and were loaded to approximately 50% of their capacity before the aircraft impact. The core columns were weakened significantly by thermal effects and by the aircraft impact damage. Thermal effects dominated the weakening of WTC 1.
As the fires moved from the north to the south side of the core, the WTC 1 core was weakened over time by significant creep strains on its south side. Aircraft impact damage dominated the weakening of WTC 2. Immediately after impact, the vertical displacement at the southeast corner of the WTC 2 core increased 15 cm, from 10 cm to 25 cm. With the impact damage, the core subsystem leaned to the southeast and was supported by the south and east floors and exterior walls. Gravity loads redistributed from the core to the exterior faces primarily through the hat truss due to aircraft impact and thermal effects.
The WTC 1 core carried 1% less load after impact but 20% less after thermal weakening. The WTC 2 core carried 6% less load after impact and 2% less load after thermal weakening. Additional axial loads that were redistributed to the exterior columns from the core were not significant (only about 20% to 25% on average), because the exterior columns were loaded to only approximately 20% of their capacity before the aircraft impact.
Role of the Building Floors
The floors were designed to support occupancy loads and transfer them to the core and exterior columns. They were also designed to act as horizontal diaphragms when the buildings were subject to high winds.
In the collapse of the towers, the floors provided inward pull forces as they sagged signifi cantly under thermal loads. However, the sagging floors continued to support their floor loads despite the dislodged insulation and extensive fires. Some truss seat connections with dislodged insulation at the exterior columns did fail and disconnect from the exterior wall under thermal loads. Floor disconnections increased the unsupported length of the exterior columns and distributed floor loads to adjacent truss seats. No inward pull forces existed where the floors were disconnected.
Role of Exterior Walls
Column instability over an extended region of the exterior face ultimately triggered the global system collapse, because the loads could not be redistributed through the hat truss to the already weakened building core. In the area of exterior column buckling, loads transferred through the spandrels to adjacent columns and adjacent exterior walls. As the exterior wall buckled, on the south face of WTC 1 and the east face of WTC 2, column instability propagated to adjacent faces and caused the initiation of the building collapse.
The exterior wall instability was induced by a combination of thermal weakening of the columns, inward pull forces from sagging floors, and to a much lesser degree, additional axial loads redistributed from the core.
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