How the WTC collapsed...

www.tms.org...

Why Did the World Trade Center Collapse? Science, Engineering, and Speculation by Thomas Eagar and Christopher Musso

There have been numerous reports detailing the cause of the World Trade Center Tower collapse on September 11, 2001. Most have provided qualitative explanations; however, simple quantitative analyses show that some common conclusions are incorrect; for example, the steel could not melt in these flames and there was more structural damage than merely softening of the steel at elevated temperatures. Some guidelines for improvements in future structures are presented.

INTRODUCTION
The collapse of the World Trade Center (WTC) towers on September 11, 2001, was as sudden as it was dramatic; the complete destruction of such massive buildings shocked nearly everyone. Immediately afterward and even today, there is widespread speculation that the buildings were structurally deficient, that the steel columns melted, or that the fire suppression equipment failed to operate. In order to separate the fact from the fiction, we have attempted to quantify various details of the collapse.

The major events include the following:

The airplane impact with damage to the columns.

The ensuing fire with loss of steel strength and distortion (Figure 1).

The collapse, which generally occurred inward without significant tipping (Figure 2).

Each will be discussed separately, but initially it is useful to review the overall design of the towers.




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[edit on 12-9-2004 by Banshee]

This is a good and seemingly sound analysis of the structural collapse of the towers. I also like the philosophical observations. It's probably not a good idea to post the whole article, though.

[edit on 04/9/12 by GradyPhilpott]

The floors pancaked down on one another, after the implosion.
Notice the way the towers collapsed inward? Sucking some of the smoke inwards?

Ever give any thought to the boilers in the basement of the WTC, and the amount of oil that was held in the boiler rooms? The boilers had to be HUGE to gv pressure to force heat/hot water to the 110th flr.
The Titanic had 29 boilers and caused an explosion upon impact with the icy water.

[edit on 12-9-2004 by LL1]

I don't know how any of you will find this, but if you watch 9/11: The Filmmaker's Commemorative Edition, the best documentary on the WTC event, there is a firefighter shown talking to his buddies and one of the things he brings up is his astonishment at how the floors "pancaked." He used the exact words "like it was a controlled detonation" or something like that.

So even the people who were inside those buildings saw that the collapse was unusual.

Originally posted by sweatmonicaIdo
He used the exact words "like it was a controlled detonation" or something like that So even the people who were inside those buildings saw that the collapse was unusual.

Read the article, monica. The collapses are explained in very technical terms. The collapse began on the floors where the fires were and went down from there. If you watch the videos, this much is obvious.

[edit on 04/9/12 by GradyPhilpott]

Scroll to see the Implosion...

www.civil.usyd.edu.au...

BTW the buildings were rather hollow.