Citat:
Ursprungligen postat av Azzabrazza
Inte tillräkligt radikalt att en kollaps var att förvänta
Vad baserar du det på?
Citat:
Ursprungligen postat av Azzabrazza
I NIST hypotes är det ju inte eldens styrka som är avgörande, utan den bygger för och främst på spridningen av elden och hur vissa delar blivit kritiskt ansatta. Det är iallafall så jag tolkar det.
NIST skriver så här
"the WTC towers collapsed because: (1) the impact of the planes severed and damaged support columns, dislodged fireproofing insulation coating the steel floor trusses and steel columns, and widely dispersed jet fuel over multiple floors; and (2) the subsequent unusually large, jet-fuel ignited multi-floor fires weakened the now susceptible structural steel."
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm
Vad menar du med styrka?
Mer detaljerat men ändå kortfattat om förloppet skriver man om WTC 1 att
"In WTC 1, the fires weakened the core columns and caused the floors on the south side of the building to sag. The floors pulled the heated south perimeter columns inward, reducing their capacity to support the building above. Their neighboring columns quickly became overloaded as columns on the south wall buckled. The top section of the building tilted to the south and began its descent. The time from aircraft impact to collapse initiation was largely determined by how long it took for the fires to weaken the building core and to reach thesouth side of the building and weaken the perimeter columns and floors."
och om WTC 2 att
In WTC 2, the core was damaged severely at the southeast corner and was restrained by the east and south walls via the hat truss and the floors. The steady burning fires on the east side of the building caused the floors there to sag. The floors pulled the heated east perimeter columns inward, reducing their capacity to support the building above. Their neighboring columns quickly became overloaded as columns on the east wall buckled. The top section of the building tilted to the east and to the south and began its descent. The time from aircraft impact to collapse initiation was largely determined by the time for the fires to weaken the perimeter columns and floor assemblies on the east and the south sides of the building. WTC 2 collapsed more quickly than WTC 1 because there was more aircraft damage to the building core and there were early and persistent fires on the east side of the building, where the aircraft had extensively dislodged insulation from the structural steel."
http://wtc.nist.gov/pubs/NCSTAR1ExecutiveSummary.pdf