Re: Unicità delle TT: si possono confrontare con altri grattacieli?
Inviato da gandalf il 31/8/2006 21:45:24
MAx, leggi meglio il link che ho postato e che ha riportato Henry.... Il NIST alcune risposte le da, quanto alla loro sostenibilità.......non saprei data la mia ignoranza in materia.
In particolare ho trovato importanti queste dichiarazioni:
6. How could the WTC towers collapse in only 11 seconds (WTC 1) and 9 seconds (WTC 2)—speeds that approximate that of a ball dropped from similar height in a vacuum (with no air resistance)?
NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A).
As documented in Section 6.14.4 of NIST NCSTAR 1, these collapse times show that:
“… the structure below the level of collapse initiation offered minimal resistance to the falling building mass at and above the impact zone. The potential energy released by the downward movement of the large building mass far exceeded the capacity of the intact structure below to absorb that energy through energy of deformation.
Since the stories below the level of collapse initiation provided little resistance to the tremendous energy released by the falling building mass, the building section above came down essentially in free fall, as seen in videos. As the stories below sequentially failed, the falling mass increased, further increasing the demand on the floors below, which were unable to arrest the moving mass.”
In other words, the momentum (which equals mass times velocity) of the 12 to 28 stories (WTC 1 and WTC 2, respectively) falling on the supporting structure below (which was designed to support only the static weight of the floors above and not any dynamic effects due to the downward momentum) so greatly exceeded the strength capacity of the structure below that it (the structure below) was unable to stop or even to slow the falling mass. The downward momentum felt by each successive lower floor was even larger due to the increasing mass.
From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse. Neither the duration of the seismic records nor video evidence (due to obstruction of view caused by debris clouds) are reliable indicators of the total time it took for each building to collapse completely.
Non riesco a convincermi come sia potuto accadere nella maniera descritta dal NIST…. Qui si dice che le strutture di suporto erano progettate per sostenere solo il peso statico dei piani superiori e non per reggere l’effetto dinamico del movimento di caduta della parte superiore. Ma il concetto di ridondanza non esiste?
Se veramente era il Core quello che si vede da alcune foto e alcuni video restare in piedi per alcuni secondi dopo il collasso delle torri questo significa che hanno ceduto tutte le colonne esterne contemporanenamente ai supporti che legavano i singoli piani al core centrale….. Tutto ciò simultaneamente? Senza la minima resistenza?? E quando si piega in avanti la parte superiore del WTC2, quella massa non gravava in parte fuori dal perimetro della torre? E in questo caso come ha potuto causare il crollo di tutta la torre quasi istantaneamente?
11. Why do some photographs show a yellow stream of molten metal pouring down the side of WTC2 that NIST claims was aluminum from the crashed plane although aluminum burns with a white glow?
NIST reported (NCSTAR 1-5A) that just before 9:52 a.m., a bright spot appeared at the top of a window on the 80th floor of WTC 2, four windows removed from the east edge on the north face, followed by the flow of a glowing liquid. This flow lasted approximately four seconds before subsiding. Many such liquid flows were observed from near this location in the seven minutes leading up to the collapse of this tower. There is no evidence of similar molten liquid pouring out from another location in WTC 2 or from anywhere within WTC 1.
……………………
NIST concluded that the source of the molten material was aluminum alloys from the aircraft ……………………
Pure liquid aluminum would be expected to appear silvery. However, the molten metal was very likely mixed with large amounts of hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions and computers) which can display an orange glow, much like logs burning in a fireplace. The apparent color also would have been affected by slag formation on the surface.
I muri divisori, la moquette e pc rendono giallo l’alluminio fuso? E cosa sono le slag formation??
12. Did the NIST investigation look for evidence of the WTC towers being brought down by controlled demolition? Was the steel tested for explosives or thermite residues? The combination of thermite and sulfur (called thermate) "slices through steel like a hot knife through butter."
NIST did not test for the residue of these compounds in the steel……
Qui ci si mette una bella pietra sopra…….Non ci hanno guardato.
13. Why did the NIST investigation not consider reports of molten steel in the wreckage
from the WTC towers?
NIST investigators and experts from the American Society of Civil Engineers (ASCE) and the Structural Engineers Association of New York (SEONY)—who inspected the WTC steel at the WTC site and the salvage yards—found no evidence that would support the melting of steel in a jet-fuel ignited fire in the towers prior to collapse. The condition of the steel in the wreckage of the WTC towers (i.e., whether it was in a molten state or not) was irrelevant to the investigation of the collapse since it does not provide any conclusive information on the condition of the steel when the WTC towers were standing.
NIST considered the damage to the steel structure and its fireproofing caused by the aircraft impact and the subsequent fires when the buildings were still standing since that damage was responsible for initiating the collapse of the WTC towers.
Under certain circumstances it is conceivable for some of the steel in the wreckage to have melted after the buildings collapsed. Any molten steel in the wreckage was more likely due to the high temperature resulting from long exposure to combustion within the pile than to short exposure to fires or explosions while the buildings were standing.
Sotto certe circostanze è ipotizzabile che parte dell’acciaio nel cumulo si sia fuso dopo che le torri collassarono? Qualsiasi acciaio fuso nei detriti è più probabilmente dovuto alle alte temperature risultanti da una lunga esposizione alla combustione sotto la pila che non a piccole esposizioni a fuoco o esplosioni quando le torri erano ancora in piedi?? Qui siamo alle ipotesi pure…… E’ più probabile sulla base di cosa?? Perché?? Come ha fatto a fondere sotto le macerie?? Come a fatto a non soffocare il fuoco e il calore in assenza di ossigeno?? C’era chi tra gli addetti alla rimozione dei detriti ha dichiarato di passare in posti dove a lati vi erano rivoli di metallo fuso che fuoriuscivano dalle macerie!!! Non stiamo parlando quindi di una profondità sotto le macerie, stiamo parlando di soccorritori che camminano sulla superficie circondati da rivoli di metallo fuso…….
Sul WTC7 la spiegazione abbozzata da adito a numerose domande:
14. Why is the NIST investigation of the collapse of WTC 7 (the 47-story office building that collapsed on Sept. 11, 2001, hours after the towers) taking so long to complete? Is a controlled demolition hypothesis being considered to explain the collapse?
When NIST initiated the WTC investigation, it made a decision not to hire new staff to support the investigation. After the June 2004 progress report on the WTC investigation was issued, the NIST investigation team stopped working on WTC 7 and was assigned full-time through the fall of 2005 to complete the investigation of the WTC towers. With the release and dissemination of the report on the WTC towers in October 2005, the investigation of the WTC 7 collapse resumed. Considerable progress has been made since that time, including the review of nearly 80 boxes of new documents related to WTC 7, the development of detailed technical approaches for modeling and analyzing various collapse hypotheses, and the selection of a contractor to assist NIST staff in carrying out the analyses. It is anticipated that a draft report will be released by early 2007.
The current NIST working collapse hypothesis for WTC 7 is described in the June 2004 Progress Report on the Federal Building and Fire Safety Investigation of the World Trade Center Disaster (Volume 1, page 17, as well as Appendix L), as follows:
• An initial local failure occurred at the lower floors (below floor 13) of the building due to fire and/or debris-induced structural damage of a critical column (the initiating event) which supported a large-span floor bay with an area of about 2,000 square feet;
• Vertical progression of the initial local failure occurred up to the east penthouse, and as the large floor bays became unable to redistribute the loads, it brought down the interior structure below the east penthouse; and
• Triggered by damage due to the vertical failure, horizontal progression of the failure across the lower floors (in the region of floors 5 and 7 that were much thicker and more heavily reinforced than the rest of the floors) resulted in a disproportionate collapse of the entire structure.
This hypothesis may be supported or modified, or new hypotheses may be developed, through the course of the continuing investigation. NIST also is considering whether hypothetical blast events could have played a role in initiating the collapse. While NIST has found no evidence of a blast or controlled demolition event, NIST would like to determine the magnitude of hypothetical blast scenarios that could have led to the structural failure of one or more critical elements.
Il NIST sta considerando se ipotetici eventi esplosivi possano avere avuto un ruolo nell’iniziare il collasso!!! E vuole calcolare la magnitudine di ipotetiche esplosioni che possano avere portato al cedimento strutturale……anche se non ha trovato evidenze di una demolizione controllata con esplosivi…. Ma la spiegazione che da è:
Cedimento locale al 13° piano a causa del fuoco e/o detriti ha indotto a un danno strutturale a una colonna critica che supportava un piano di 2000 piedi quadrati… Il cedimento locale si è propagato verticalmente provocando la caduta della struttura interna facendo partire la progressione per linee orrizontali del crollo…….
Domanda: ma nessuno ha idea di come era la struttura del WTC7? Esistono progetti, piantine, copie cianografiche??
Scusate le considerazioni e le domande forse banali ma mi sono venute spontanee…
In particolare ho trovato importanti queste dichiarazioni:
6. How could the WTC towers collapse in only 11 seconds (WTC 1) and 9 seconds (WTC 2)—speeds that approximate that of a ball dropped from similar height in a vacuum (with no air resistance)?
NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A).
As documented in Section 6.14.4 of NIST NCSTAR 1, these collapse times show that:
“… the structure below the level of collapse initiation offered minimal resistance to the falling building mass at and above the impact zone. The potential energy released by the downward movement of the large building mass far exceeded the capacity of the intact structure below to absorb that energy through energy of deformation.
Since the stories below the level of collapse initiation provided little resistance to the tremendous energy released by the falling building mass, the building section above came down essentially in free fall, as seen in videos. As the stories below sequentially failed, the falling mass increased, further increasing the demand on the floors below, which were unable to arrest the moving mass.”
In other words, the momentum (which equals mass times velocity) of the 12 to 28 stories (WTC 1 and WTC 2, respectively) falling on the supporting structure below (which was designed to support only the static weight of the floors above and not any dynamic effects due to the downward momentum) so greatly exceeded the strength capacity of the structure below that it (the structure below) was unable to stop or even to slow the falling mass. The downward momentum felt by each successive lower floor was even larger due to the increasing mass.
From video evidence, significant portions of the cores of both buildings (roughly 60 stories of WTC 1 and 40 stories of WTC 2) are known to have stood 15 to 25 seconds after collapse initiation before they, too, began to collapse. Neither the duration of the seismic records nor video evidence (due to obstruction of view caused by debris clouds) are reliable indicators of the total time it took for each building to collapse completely.
Non riesco a convincermi come sia potuto accadere nella maniera descritta dal NIST…. Qui si dice che le strutture di suporto erano progettate per sostenere solo il peso statico dei piani superiori e non per reggere l’effetto dinamico del movimento di caduta della parte superiore. Ma il concetto di ridondanza non esiste?
Se veramente era il Core quello che si vede da alcune foto e alcuni video restare in piedi per alcuni secondi dopo il collasso delle torri questo significa che hanno ceduto tutte le colonne esterne contemporanenamente ai supporti che legavano i singoli piani al core centrale….. Tutto ciò simultaneamente? Senza la minima resistenza?? E quando si piega in avanti la parte superiore del WTC2, quella massa non gravava in parte fuori dal perimetro della torre? E in questo caso come ha potuto causare il crollo di tutta la torre quasi istantaneamente?
11. Why do some photographs show a yellow stream of molten metal pouring down the side of WTC2 that NIST claims was aluminum from the crashed plane although aluminum burns with a white glow?
NIST reported (NCSTAR 1-5A) that just before 9:52 a.m., a bright spot appeared at the top of a window on the 80th floor of WTC 2, four windows removed from the east edge on the north face, followed by the flow of a glowing liquid. This flow lasted approximately four seconds before subsiding. Many such liquid flows were observed from near this location in the seven minutes leading up to the collapse of this tower. There is no evidence of similar molten liquid pouring out from another location in WTC 2 or from anywhere within WTC 1.
……………………
NIST concluded that the source of the molten material was aluminum alloys from the aircraft ……………………
Pure liquid aluminum would be expected to appear silvery. However, the molten metal was very likely mixed with large amounts of hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions and computers) which can display an orange glow, much like logs burning in a fireplace. The apparent color also would have been affected by slag formation on the surface.
I muri divisori, la moquette e pc rendono giallo l’alluminio fuso? E cosa sono le slag formation??
12. Did the NIST investigation look for evidence of the WTC towers being brought down by controlled demolition? Was the steel tested for explosives or thermite residues? The combination of thermite and sulfur (called thermate) "slices through steel like a hot knife through butter."
NIST did not test for the residue of these compounds in the steel……
Qui ci si mette una bella pietra sopra…….Non ci hanno guardato.
13. Why did the NIST investigation not consider reports of molten steel in the wreckage
from the WTC towers?
NIST investigators and experts from the American Society of Civil Engineers (ASCE) and the Structural Engineers Association of New York (SEONY)—who inspected the WTC steel at the WTC site and the salvage yards—found no evidence that would support the melting of steel in a jet-fuel ignited fire in the towers prior to collapse. The condition of the steel in the wreckage of the WTC towers (i.e., whether it was in a molten state or not) was irrelevant to the investigation of the collapse since it does not provide any conclusive information on the condition of the steel when the WTC towers were standing.
NIST considered the damage to the steel structure and its fireproofing caused by the aircraft impact and the subsequent fires when the buildings were still standing since that damage was responsible for initiating the collapse of the WTC towers.
Under certain circumstances it is conceivable for some of the steel in the wreckage to have melted after the buildings collapsed. Any molten steel in the wreckage was more likely due to the high temperature resulting from long exposure to combustion within the pile than to short exposure to fires or explosions while the buildings were standing.
Sotto certe circostanze è ipotizzabile che parte dell’acciaio nel cumulo si sia fuso dopo che le torri collassarono? Qualsiasi acciaio fuso nei detriti è più probabilmente dovuto alle alte temperature risultanti da una lunga esposizione alla combustione sotto la pila che non a piccole esposizioni a fuoco o esplosioni quando le torri erano ancora in piedi?? Qui siamo alle ipotesi pure…… E’ più probabile sulla base di cosa?? Perché?? Come ha fatto a fondere sotto le macerie?? Come a fatto a non soffocare il fuoco e il calore in assenza di ossigeno?? C’era chi tra gli addetti alla rimozione dei detriti ha dichiarato di passare in posti dove a lati vi erano rivoli di metallo fuso che fuoriuscivano dalle macerie!!! Non stiamo parlando quindi di una profondità sotto le macerie, stiamo parlando di soccorritori che camminano sulla superficie circondati da rivoli di metallo fuso…….
Sul WTC7 la spiegazione abbozzata da adito a numerose domande:
14. Why is the NIST investigation of the collapse of WTC 7 (the 47-story office building that collapsed on Sept. 11, 2001, hours after the towers) taking so long to complete? Is a controlled demolition hypothesis being considered to explain the collapse?
When NIST initiated the WTC investigation, it made a decision not to hire new staff to support the investigation. After the June 2004 progress report on the WTC investigation was issued, the NIST investigation team stopped working on WTC 7 and was assigned full-time through the fall of 2005 to complete the investigation of the WTC towers. With the release and dissemination of the report on the WTC towers in October 2005, the investigation of the WTC 7 collapse resumed. Considerable progress has been made since that time, including the review of nearly 80 boxes of new documents related to WTC 7, the development of detailed technical approaches for modeling and analyzing various collapse hypotheses, and the selection of a contractor to assist NIST staff in carrying out the analyses. It is anticipated that a draft report will be released by early 2007.
The current NIST working collapse hypothesis for WTC 7 is described in the June 2004 Progress Report on the Federal Building and Fire Safety Investigation of the World Trade Center Disaster (Volume 1, page 17, as well as Appendix L), as follows:
• An initial local failure occurred at the lower floors (below floor 13) of the building due to fire and/or debris-induced structural damage of a critical column (the initiating event) which supported a large-span floor bay with an area of about 2,000 square feet;
• Vertical progression of the initial local failure occurred up to the east penthouse, and as the large floor bays became unable to redistribute the loads, it brought down the interior structure below the east penthouse; and
• Triggered by damage due to the vertical failure, horizontal progression of the failure across the lower floors (in the region of floors 5 and 7 that were much thicker and more heavily reinforced than the rest of the floors) resulted in a disproportionate collapse of the entire structure.
This hypothesis may be supported or modified, or new hypotheses may be developed, through the course of the continuing investigation. NIST also is considering whether hypothetical blast events could have played a role in initiating the collapse. While NIST has found no evidence of a blast or controlled demolition event, NIST would like to determine the magnitude of hypothetical blast scenarios that could have led to the structural failure of one or more critical elements.
Il NIST sta considerando se ipotetici eventi esplosivi possano avere avuto un ruolo nell’iniziare il collasso!!! E vuole calcolare la magnitudine di ipotetiche esplosioni che possano avere portato al cedimento strutturale……anche se non ha trovato evidenze di una demolizione controllata con esplosivi…. Ma la spiegazione che da è:
Cedimento locale al 13° piano a causa del fuoco e/o detriti ha indotto a un danno strutturale a una colonna critica che supportava un piano di 2000 piedi quadrati… Il cedimento locale si è propagato verticalmente provocando la caduta della struttura interna facendo partire la progressione per linee orrizontali del crollo…….
Domanda: ma nessuno ha idea di come era la struttura del WTC7? Esistono progetti, piantine, copie cianografiche??
Scusate le considerazioni e le domande forse banali ma mi sono venute spontanee…
Messaggio orinale: https://old.luogocomune.net/site/newbb/viewtopic.php?forum=4&topic_id=1908&post_id=45024