didn’t find this question after a cursory glance thru the archives, so I’ll give a shot.
The second WTC Tower to fall was actually the first one hit, and there was, at the time, speculation that it only actually collaped as a result of the other Tower destabilizing its foundation.
So the question here is if only the second tower (the second tower to be hit) had been hit as low down on the building as it was, would both have eventually collapsed anyway? and in if so, would this have (as I suspect) actually caused more casualties?
My reasoning here is that perhaps fewer peolpe might have evacuated the tower that wasn’t hit, then upon the collapse of the first tower they would have been trapped inside by the rubble of the first tower, until theirs (the one not hit) collapsed as well.
Purely a speculative question, not questioning the efficacy of the attacks, but i was wondering in my head what had happened if the Air Force had been able to scramble and intercept the second plane? unfortunately I realize that this is an entirely different question, as the second plane was the one that did more damage, and caused the inital collapse. So this one is purely theoretical.
I don’t think it would have; from all the information I have seen, it wasn’t the impact damage that caused the towers to fall; it was the loss of structural strength in the steel as a result of the fires.
You can see when the second tower collapses, it doesnt even ‘‘collapse’’ from the ground, but from the section it was hit, and from there on it is just a domino effect.
Part of their collapse was caused by the enormous shockwave from the towers comming down. The walls of nearby buildings were blown in.
as for the OP - both towers were being evac’ed after the 1st attack - some stayed to watch but this is always the case. If only one plane hit I would guess the 2nd would have stood but might have had to be knocked at a latter time down due to structural problems.
Contrary to what I still hear in the media from time-to-time, they were very strong buildings that were very well built. According to every anecdotal engineering source I know, the falling of one tower should not have seriously damaged the other to the point where it should fall as well.
The north tower (WTC1) was the first to be hit, but the south tower was the first to fall after having been hit further down. There was, I believe, about 20 minutes gap between the two collapses. Both buildings remained standing after the impacts; the fires caused the collapses.
All the buildings were on their own foundations, which rest on bedrock, so they weren’t connected structurally. The lower surrounding buildings were damaged not only by the air blast but by flying debris, including very large H-beams falling from great heights.
I’ve been to a presentation made by some of the investigating engineers and read numerous articles in engineering magazines. One of the things they’re struggling with is why some buildings collapsed and others didn’t. The hotel at the base of the towers performed well, despite having first flaming airplane debris, and then a whole building fall on it. It’s still unclear why 7 WTC came down, but they were focusing on apparently fire-damaged steel recovered from that building, speculating that flaming debris from the towers may somehow have touched off underground fuel tanks for emergency generators in that building.
I know the WTC towers were somewhat uniqie in how the were built (sort of the “tube concept”), in that you could remove a chunk of a side and the building would stand. It did not depend on internal structure as much, rather, the perimiter girders/beams held it up and used the others for redundancy Like a paper roll, if you stood it up on end and removed half the mass from an area, it’d stand…like it did.
It didn’t face any “problems” per se, because the steel structure permitted it to be flexible, strong and space efficient - Something clumsier buildings (which depended on concrete and other limitting desing) couldn’t match.
Some buildings with a stronger exterior might have deflected more of the plane’s mass, and less fuel might have entered the buiding. In high rise buildings with lots of glass and steel, much of the plane will explode inside rather than outside, and fire will doom it.
Many buildings are just as succeptable as the WTC was. You just can’t have steel that stands those temps. Shorter buildings can be built like fortresses, where concrete does more deflecting.
So, you can have castles all over big cities, or you can build tall , flexible steel and glass structures.
Both buildings collapsed because of steel failure from temps. Surrounding buildings took a debris bombing and shockwave blast. The whole area was very connected.
according to two recent TV programmes here in UK, there were several problems with the WTC design that might have sped up the collapse. The first was the flimsy fireproofing of the central core and surrounding the steel girders. A concrete core would have slowed the fire and allowed more people to escape. The second place was the method of attachment of the crossbeams to the steel frame outside which gave way under the extreme heat.
I don’t think it was so much “flimsy fireproofing” as it was that no one expected a plane crash into the buildings to be direct (rather than glancing) and deliberate.
Most skyscrapers have a steel inner skeleton, and the outside is merely a “curtain” that hangs off this solid inner framework. The WTC towers, however, were designed like big steel tubes. They had a very solid (yet still flexible) steel outer skeleton, combined with a core that housed stairs, elevators, and other supporting elements. This allowed for very open floor plans, which made the towers attractive office real estate.
Inside the towers, floors were made of concrete panels above a steel lattice, riveted at both ends to the steel core and exterior. The steel was sprayed with fireproofing material. These riveted floors helped the outer and inner supporting structure to keep each other aligned; they didn’t bear weight, but they kept things in line.
When the planes hit, they caused massive damage to the floor panels they struck. The initial explosion knocked most of the fireproofing material off the steel latticework under the other nearby floor panels, exposing the steel to the burning jet fuel. The steel didn’t have to actually melt; the increased heat weakened the steel enough that it could bend more easily.
So, with the floor panels collapsed and collapsing away, in essence the upper portion of each tower was supported by only rigid steel “stilts” perhaps 60 feet long. A massive weight can’t balance like that for long; the slightest twist brings it all down. Plus, with the fire weakening the steel, eventually they had to give.
My conclusion: no, the collapse of one tower would not have caused the other to collapse, based on its internal design. Internal floor sections would have to be destroyed and the steel outer and inner skeletons would have to be weakened before collapse would be possible.