why did the twin towers collapse?

Question

i know the planes crashed into them!! but why didnt the bottom stay put, was it due to extra explosions inside or is to do with how they are built

Answer 1

A combination of factors. The force of the planes crashing through the main structure would have taken out many of the load bearing supports (as obviously buildings are not built to withstand an attack like this but rather to stay upright in high winds etc); the explosion of the impact would have created further structural damage; the heat of the burning jet fuel would have then (quite likely) super heated any remaining steel supports creating a weakening...the combination would eventually lead to the upper floors falling down towards the point of impact. At that point a critical mass of gravity takes over, tens of thousands of tons of building materials falling directly down would cause crushing impact that could not and was not sustained by the structurual support and as the tiop part fell it gained momentum with increased weight adding to the overall collapsing effect - all the way to the bottom

Answer 2

As with what the sensible people above said. The Twin Towers were supported by a central column of steel with struts going outwards, rather than an external 'jacket' of steel round the outer walls like many other high structures. So as the weight of the building above crashed down, the force would have been highly concentrated around the central column which then collapsed. If the buildings had had an external 'jacket' then perhaps the bottom half would have survived as the weight would have been more dissipated, but who knows? These buildings were designed to support their own weight and accomodate wind and other forces, but were not built to withstand a large impact force from above - why would they be?

Answer 3

Plenty will probably answer this by the time I've typed it out.
The planes had just taken off so they were full of fuel, that's why they made hollywood style fireballs on impact.
Besides the damage caused by the impact, the buildings remained standing. The problem was that because of the fuel there were very intense fires tat heated the steel frame of the building to the point where it became softer and could no longer hold up the building above the point of impact.
Once the couple of damaged floors collapsed, the immense weight of the floors above fell on the floor below. That's like holding your neighbours house over yours and dropping it on top. This made the next floor down collapse, that rubble added to the wieght above and it was just a domino effect until the whole lot was on the floor.

Answer 4

Don't believe the conspiracy theory nutjobs. If you watch the video of the buildings collapsings you can see that as the top floors that were damaged started to fall the weight started a chain reaction. Go watch a video of a controlled collapse,and then watch the video of the towers they are nothing alike,and there is no series of explosions in the Twin towers that would be needed for a controlled colapse.

Answer 5

The planes crashed near the center top of the building, causing damage and fire. The fires weakened the inner framework of the towers causing them to give way. The top part of the tower came crashing down on the rest of the structure.

Answer 6

It is generally accepted that the impacts and explosions caused a large fire, which melted the central support, and as that gave way at the top (where the fire was) it started a chain reaction, and the falling weight of the top section brought the whole building down. This was more or less the conclusion of the official investigation.

There is, however, a popular conspiracy theory on the internet, in which the US government was complicit in the attack, and the towers were brought down by controlled demolotion.

Answer 7

If a building is 110 stories high and comes straight down, how could the bottom floors stay intact? No, there were not any internal explosions, and no it was not a conspiracy. The end.

Answer 8

it had explosion at the bottom of the towers. i think there is a DVD about the truth what actually happened on 9/11.

Answer 9

Faulty high-rise buildings highly wired with smokes detectors and cooking gas with highly combustible furnishing that gave way to the building collaspe in planet of apes.
The mystery of us-911 on a highly fuse building waiting for time to go off.

Answer 10

I have heard that when one of the journalists was filming at the scene he heard loud bangs and said so on his report. Then the towers started to collapse.

This supports the assumption, that the planes were not entirely liable.