Demand the Truth

[Dr3am]

"I don't care about any of that. I want to know physically how the towers collapsed. I want to know why there was controlled demolition of tower 7. Those are the only questions I want answered. I don't care about anything beyond those two specific issues.

Answer my questions please."

I did a report on this for college years ago and I remember some of the details, so here goes. It has been a while so my details might be off here or there, but you get the picture.

1) Why did the steel girders melt at such low temperatures?
The answer to this lies within something called phase transitions when you heat metal. Sure the melting point of steel occurs much higher than jet fuel burns, but we don't need to melt the girders to make the building fall. At 700f industrial steel goes through its first phase transition and loses more than half of its tensile strength.
If you investigate the building itself you find that the steel coating the outside of the building is connected to a steel core in the middle of the building via steel trusses. These trusses keep the skin of the building in place, and as major wind forces hit the building it spreads the stress along the skin, through the trusses, and into the interior of the build. When the tensile strength of the buildings gave out, the trusses softened, causing the outside skin to buckle. Once this happened, the weigh to of the building above no longer was supported by the skin of the building in that area, resulting in the top of the building pushing down into nothing. This resulted in a collapse of the top of the building via the 6 stories of melted trusses. Look at it like a straw, and when you push straight down on the top of a straw it holds far more weight than it should due to the skin of the straw reinforcing itself throught its length. Now take the same straw and fold it then try to push down again- because the skin is no longer aligned the weight on top causes it to almost immediately give and no longer hold weight.

2) The buildings fell at the speed of freefall- had you dropped a penny from the top floor at the beginning of the collapse, it would impact the ground at the same time the top floor did.
This is true and the reasons behind it are amazing to consider. The building design (that I allude to above) was created for each floor to hold the static weight of all floors above it. In each case the buildings were struck with between 20 and 40 floors above them- and when they fell their weight became dynamic and not static. When that dynamic weight pushed on the floors below, it actually pulverized them because the static weight is nowhere near as immense as the dynamic weight. Bear in mind these buildings were not normal office buildings- they occupied an entire NY city block. Each. Their dynamic weight was so immense that the floors below could not even begin to resist it- they simply pulverized into dust. The forces involved when an entire city block sized 20 to 40 story building bears down on another force is hard to imagine much less calculate.

3) Tower 7 fell like a controlled demolition.
The lower floors of Tower 7 were completely obliterated by the falling debris by the trade centers, and all the load bearing structures on that floor were decimated. A key structural support that held the entire building together, at the center of the building, was destroyed. This is why the building was evacuated and expected to fall, and why it fell within its own footprint. It's actually a miracle that it stood as long as it did.

4) The twin towers fell like a controlled demolition.
http://www.cleveland.com/science/ind...1_attacks.html
Halfway down on the right hand side you will see a picture of the second tower collapsing at the initiation of the collapse. You can clearly see from this picture that the tower top fell to the left and then down, because the plane hollowed out and softened the support structures on the left of that tower.