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Single Point of Failure - How the Loss of One Column May Have Led to the Collapse of WTC 7

More food for thought for the 9/11 truthers.

http://www.structuremag.org/article.aspx?articleID=284

Single Point of Failure:
How the Loss of One Column May Have Led to the Collapse of WTC 7
Ramon Gilsanz, P.E., S.E., Willa Ng

The collapses of World Trade Center 1 (WTC 1) and World Trade Center 2 (WTC 2) on September 11, 2001 were attributed to the impact of two airplanes and the ensuing fires. The subsequent collapse of World Trade Center 7 (WTC 7), which was not directly struck by airplanes, is more of an enigma. Additionally, the nature of its collapse, which occurred nearly seven hours after WTC 1 and WTC 2 failed, has led to rampant speculation.
http://www.structuremag.org/images/1107-f2-1.jpg

The following analysis shows that, although there were several phases leading to the global collapse of WTC 7, the building likely would have remained standing if not for the failure of one critical column. The location of this column, and its role as a key structural component, meant that its local failure caused the global failure of WTC 7.
The Federal Emergency Management Agency (FEMA) Building Performance Assessment Team and the National Institute of Standards and Technology (NIST) formed a team to analyze the collapse of WTC 7. The effort began with the collection of structural pieces, existing plans, eyewitness accounts, and photos and videos taken that day. This information led to the formation of several probable collapse theories. The team then created a computerized model of the building, using existing plans and information, to test these theories.
http://www.structuremag.org/images/1107-f2-2.gif

WTC 7, one of the seven buildings that formed the World Trade Center complex in New York City, was bounded by Washington Street, West Broadway, Barclay Street and Vesey Street. This 47-story commercial office building was approximately 330 feet long, 140 feet wide and 610 feet tall, and was constructed over a pre-existing electrical substation owned by Con Edison. The original plans for the substation included the construction of a high-rise tower above it. However, the final footprint of WTC 7 was larger than the originally planned high-rise tower. As a result, there were discontinuities between the columns in the Con Edison substation and the columns for the rest of WTC 7. Braced frames, transfer trusses and transfer girders at floors 5 through 7 transferred loads between the discontinuous columns. These elements, though serving the purpose of shifting loads from one set of columns to another, also essentially "tied" the columns to each other. The columns were numbered for ease of identification and will be referred to by their number herein.
The failure of WTC 1 and WTC 2 sent flaming debris into the southern face of WTC 7. This impact and fire damage initiated a sequence that would lead to global collapse. Eyewitness observations by building occupants, NYPD, FDNY and bystanders indicated that the damage was located on the south face between floors 8 and 18, and that there was a fully involved fire on the south side of floor 7, which included the transfer elements. From 3:00 to 5:00 PM, fires were still burning in the building, which may explain why it took several hours for it to collapse. The continued heat of the fire weakened steel structural components until they failed at 5:21 PM, nearly seven hours after the collapse of WTC 1 and WTC 2.
http://www.structuremag.org/images/1107-f2-3.gif

The final collapse of WTC 7 occurred over 8.2 seconds and was recorded on several videos from locations northeast and northwest of the building. Study of these videos led to the development of the timeline of the visible external sequence of events. The images accompanying this article are taken from a CBS News Archives video to show key points observed during the collapse. As seen in the photos, a kink develops in the east penthouse before it falls into the building. The west penthouse then fails, followed by a kink in the entire façade of the building. Total collapse follows.
This sequence of events, with roof elements sinking into a building with an intact façade, suggests an interior failure. An interior failure would explain the appearance of a "controlled" collapse with a relatively small debris field, as seen with WTC 7.
The sequence of final collapse can be interpreted using knowledge of the building’s framing from existing plans. For instance, the observed collapse of the east penthouse may signify a failure in a line of columns on the east side of the building (columns 76-81). In particular, interior columns 79, 80 and 81 were located directly below the east penthouse and supported relatively large tributary areas.
http://www.structuremag.org/images/1107-f2-4.gif

The final collapse hypothesis can be summarized as follows:
1) Debris from the collapse of WTC 1 and WTC 2 caused damage from impact and fire.
2) Fire significantly weakened structural steel and caused the failure of one or more of the columns on the eastern side of the building, as evidenced in the sinking of the east penthouse. This indicated a vertical progression of failure from the damage on the lower floors to the failure of the penthouse on the roof.
3) The sinking of the west penthouse, as well as the shifting of a clear kink from the east penthouse towards the middle of the structure, indicates that the collapse then progressed horizontally, as the localized failure of the eastern columns was distributed to the other columns through the transfer elements at floors 5 through 7.
4) Global collapse was the ultimate result.

http://www.structuremag.org/images/1107-f2-5.gif

Full Article: http://www.structuremag.org/article.aspx?articleID=284

More good info: http://www.debunking911.com/pull.htm


Added: Jun-9-2012 Occurred On: Jun-9-2012
By: j_ramone
In:
Conspiracy
Tags: wtc 7, collapse, pull, 9/11
Location: United States (load item map)
Views: 3289 | Comments: 34 | Votes: 0 | Favorites: 0 | Shared: 0 | Updates: 0 | Times used in channels: 1
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  • "pull it"

    Posted Jun-9-2012 By 

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  • You know what? I don't have a hard time believing that weakened structures can collapse. I don't have a hard time believing that damaged columns in WTC lead to its collapse.

    It's the way all of them collapse (pancaking) that really perplexes me. I'm sorry, but buildings don't collapse like that naturally. Sure, it's possible. Having one of these 3 collapse like that is a believable coincidence. Having all 3 of them collapse like that is something else altogether. In any case, there's nothing we More..

    Posted Jun-9-2012 By 

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  • troofers are funny!

    Posted Jun-9-2012 By 

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  • That's an incredibly weak argument, since nothing even close ever happened before. But the pro-government nitwits who want to believe the government's ridiculous lies, will simply go "well that settles it. The government was right all along! No conspiracy, tin foil hat wearing trooofers!"

    Posted Jun-9-2012 By 

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  • You waste your time.
    The last thing Truther's want to hear is the truth.

    Posted Jun-9-2012 By 

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  • I'm pretty sure that Rosie O'Donnell had it right when she said: "I do believe it's the first time in history that fire has melted steel"

    I'm gonna go with her on this....

    Posted Jun-9-2012 By 

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  • This is about as accurate as the 9/11 Commision Report. Pure BULLSHIT!

    Posted Jun-9-2012 By 

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  • LOFL, The minions are back to try to prove to you that building 7 fell on it's own. BIG FUCKING JOKE!. Pres. George Washington is at my house right now playing cards with me.

    Posted Jun-9-2012 By 

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  • all the videos show a controlled demolition u fucking moron

    Posted Jun-9-2012 By 

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  • Its magic physics Sunday!

    Posted Jun-10-2012 By 

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  • Democrazy of peace........and freedom

    Posted Jun-10-2012 By 

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  • rofl,theories,dreams,wishes lol,there's some good stuff to start a war with rofl.wow,with hypothesis like this it's a wonder anything over 10' tall can stand up when anyone passes gas in the vicinity,the 'official' story is a sham,sorry,but there is no way,every 'theory' posted by 'debunkers' i have heard so far is as full of holes as the 'official' story,impact,fire etc etc could not cause the collapse of these buildings,noone would spend the time and money on building demolition that they do i More..

    Posted Jun-10-2012 By 

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  • You guys are in overdrive here recently for some reason. Must be a shitty job.

    Removal method: 1xHigh school physics textbook. Read about conservation of energy. Apply this to WTC7 NIST admitted freefall and all your debunking needs are satisfied.

    Posted Jun-9-2012 By 

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    • @N4CR NIST admitted free-fall because there was no possible way to lie their way out of that. Everything after that is mostly a complete lie. The buildings still had thousands of tons of perfectly intact steel structure UNDER the damage area and the buildings fell straight down at free-fall speed ANYWAY? How does physics explain that? Shoot a 50 cannon ball up into the air then measure the free-fall speed. Now put an empty, 3 or 4 story building in the way and measure how long it took to fal More..

      Posted Jun-9-2012 By 

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    • @N4CR LOL!!! Do you have a physics book? Do you know what average means in an acceleration profile?

      NIST admits an AVERAGE of 2.5 seconds of free fall ACCELERATION on a SINGLE point on the NORTH WALL of WTC 7. NEVER do they mention the whole building is freefalling but only a single point on the OUTER facade. Funny enough that the place they measured is where the east penthouse collapsed and left a void for the roofline of the outer structure.

      Lastly, if freefall is your only proof that WTC 7 More..

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    • Comment of user 'MrPadaso' has been deleted by author (after account deletion)!
    • @Fine_Just_Fine
      >_< I was trying to make the same point and not side with them. All good. You get where I was going with it lol.

      Posted Jun-10-2012 By 

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    • @barogers619

      Considering facade point they measured is attached to the rest of the building, conservation of energy still applies. Freefall is impossible without additional energy input to remove supports.

      Posted Jun-10-2012 By 

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  • DOn't you relize that HIGH SCHOOL KIDS explained the collapse was an inside job ? They wrote the book ,
    "Loose Change" that has gone on to cult religious status
    like ALGore and his global warming pridictions that Wall street would be under water by the year 2010..
    oh
    yes he did predict that.

    Posted Jun-9-2012 By 

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    • @Airedale I predict Al Gore made enough money off his bullshit agenda that he won't ever need to write another work of fiction or do a paid speech ever again if he doesn't want to. So since he made his "fuck you" money hopefully Gore will simply fuck OFF. With his stupid nonsense.

      Posted Jun-9-2012 By 

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  • Comment of user 'MrPadaso' has been deleted by author (after account deletion)!
    • @MrPadaso
      Are you aware of the Citigroup (formerly Citicorp) building engineering crisis? You'd be surprised how often mistakes and changes lead to structurally unsound buildings. Here's a link: http://en.wikipedia.org/wiki/Citigroup_Center#Engineering_crisis_of_1978

      Posted Jun-9-2012 By 

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    • Comment of user 'MrPadaso' has been deleted by author (after account deletion)!
    • @MrPadaso
      But still, changes and mistakes are made, and the NYC construction industry was pretty corrupt in the 80's. Still, with bldg 7 we're looking at a lot of things coming together at one time. Other than a major earthquake, if WTC 1 had not damaged the building and caused the fires, it would still be standing today.

      Posted Jun-9-2012 By 

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    • Comment of user 'MrPadaso' has been deleted by author (after account deletion)!