alobee a écrit:
Il ne reste que les explosifs...
Bin non...Souviens-toi de l'incontournable
question des détonateurs...
alobee a écrit:
All four test specimens sustained the maximum design load for approcimatively 2 hours without collapsing. NIST P.143
Intéressant mais alors elle sont tombées comment ces tours ?
Suffisait de le demander. Puisque c'est ce que tu lis en diagonale en ce moment, tu n'as qu'à consulter le
NIST. Comme tu le disais si bien...
Ouvrez vos yeuxLa manoeuvre magique consiste à abandonner la superbe page 143 et à ramper jusqu'à l'horrible page 150.
Il est cependant vrai que, comme je l'ai mentionné ce matin, nous n'aborderons le délicat chapître de la compréhension de texte que l'année prochaine.
Citer:
6.14.6 Probable WTC 1 Collapse Sequence (pp.150-151)
Aircraft Impact Damage
The aircraft impact severed a number of exterior columns on the north wall from the 93rd to the 98th floors, and the wall section above the impact zone moved downward.
After breaching the building’s perimeter, the aircraft continued to penetrate into the building, severing floor framing and core columns at the north side of the core. Core columns were also damaged toward the center of the core. Insulation was damaged from the impact area to the south perimeter wall, primarily through the middle one-third to one-half of the core width.Finally, the aircraft debris removed a single exterior panel at the center of the south wall between the 94th and 96th floors.
The impact damage to the exterior walls and to the core resulted in redistribution of severed column loads, mostly to the columns adjacent to the impact zones. The hat truss resisted the downward movement of the north wall.
Loads on the damaged core columns were redistributed mostly to adjacent intact core columns and to a lesser extent to the north perimeter columns through the core floor systems and the hat truss.
As a result of the aircraft impact damage, the north and south walls each carried about 7 percent less gravity load after impact, and the east and west walls each carried about 7 percent more load. The core carried about 1 percent more gravity load after impact.
Thermal Weakening of the Structure
Under the high temperatures and stresses in the core area, the remaining core columns with damaged insulation were thermally weakened and shortened, causing the columns on the floors above to move downward. The hat truss resisted the core column shortening and redistributed loads to the perimeter walls. The north and south walls’loads increased by about 10 percent, and the east and west walls’loads increased by about 25 percent, while the core’s loads decreased by about 20 percent.
The long-span sections of the 95th to 99th floors on the south side weakened with increasing temperatures and began to sag. Early on, the floors on the north side had sagged and then contracted as the fires moved to the south and the floors cooled. As the fires intensified on the south side, the floors there sagged, and the floor connections weakened. About 20 percent of the connections on the south side of the 97th and 98th floors failed.
The sagging floors with intact floor connections pulled inward on the south perimeter columns, causing them to bow inward.
Collapse Initiation
The bowed south wall columns buckled and were unable to carry the gravity loads. Those loads shifted to the adjacent columns via the spandrels, but those columns quickly became overloaded as well. In rapid sequence, this instability spread all the way to the east and west walls.
The section of the building above the impact zone (near the 98th floor), acting as a rigid block, tilted at least 8 degrees to the south.
The downward movement of this structural block was more than the damaged structure could resist, and global collapse began.
C'est PRESQUE comme tu l'avais compris alobee...
PRESQUE
Aucun dommage d'impact d'aéronef
PRESQUE
Aucun affaiblissement structurel dû à la chaleur
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