9/11: An Architect's Guide
Part 1 - World Trade Center Building 7

Take this short quiz after watching the presentation in order to test your understanding of the material.

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1. Your Information:

Name:

Email address:

City, State:

Architect, Engineer, or Other?

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2. Prior to 9/11/01 how many steel-framed high-rise buildings have suffered complete collapse due to fire?

a. Zero

b. 2

c. 8

d. 15

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3. Because typical office fires travel somewhat chaotically and because they burn out in a given area after approximately 20 minutes, if a high-rise building were to suffer a fire-induced failure, it would most likely fail:

a. Slowly, allowing time for occupants to evacuate.

b. In stages, taking hours or many minutes, rather than seconds.

c. Asymmetrically, such as tipping over or collapsing on one side — not falling straight down through the path of greatest resistance.

d. Any of the above are likely.

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4. True or False: Sudden onset of collapse, symmetry (i.e., falling straight down), and near-free-fall acceleration are three typical features associated with fire-induced failure.

True

False

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5. Another typical feature of controlled demolition that was exhibited in the destruction of WTC 7 was:

a. Total dismemberment of the structural steel frame.

b. Enormous clouds of pulverized concrete.

c. Sounds of explosions heard by witnesses.

d. All of the above.

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6. According to the 2008 report from the National Institute of Standards and Technology (NIST), World Trade Center Building 7 collapsed primarily due to:

a. Diesel fuel fires from the diesel generators on the 5th floor.

b. Structural damage caused by debris from the collapse of WTC 1.

c. Normal offices ignited by debris from the collapse of WTC 1.

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7. The series of structural failures that NIST found to be the most likely cause of the collapse involved:

a. The thermal expansion of fire-protected, long-span floor beams.

b. The lateral movement and walk-off of the building’s largest girder, which was later proven to be connected to the concrete floor slab above it with 30 shear studs.

c. A complete failure of the internal structural steel system in less than 20 seconds, triggered by the failure of a single column.

d. A complete collapse of the building’s exterior shell in less than 7 seconds.

e. All of the above.

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8. Per NIST: For what period of time and over what distance (in terms of stories) was WTC 7 in absolute free fall?

a. There was no period of free fall. Fire cannot cause a building to collapse that quickly.

b. For less than one second over a distance of one story, i.e., a fairly insignificant duration.

c. For 2.25 seconds over a distance of eight stories, i.e., one-third of its 7-second fall.

d. For 7 seconds over a distance of 47 stories, i.e., the whole way down.

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9. True or False: NASA thermal imaging conducted on September 16, 2001, found temperatures as high as 1,340°F in the debris field of WTC 7.

True. The surface temperatures were hotter than most office fires ever get, even though there were no fires on the surface of the debris field.

False. The temperatures in WTC 7’s debris field could not have been anywhere near that hot on September 16, 2001.

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10. True or False: NIST included in its final report a detailed examination of the sulfidated steel from WTC 7 that was documented in Appendix C of the FEMA report - which The New York Times had called “perhaps the deepest mystery uncovered in the investigation.”

True. NIST included a detailed examination and a plausible explanation for the sulfidation of steel from WTC 7.

False. NIST did not follow up on the analysis documented in Appendix C of the FEMA report.

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11. What substance was discovered and analyzed in multiple, independently collected World Trade Center dust samples, according to a team of scientists led by Dr. Niels Harrit (professor of chemistry from the University of Copenhagen)?

a. Unreacted nano-thermite, a form of thermite with explosive properties engineered at the nano-level.

b. Conventional thermite, an incendiary typically used for welding railroad ties and in grenades.

c. RDX, a high-energy explosive.

d. Paint chips.

(This concludes the quiz. The following questions are optional.)

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12. Optional: Do you believe that a new investigation into the collapse of World Trade Center Building 7 is warranted?

Yes

Other (please specify)

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13. Optional: Would you like to receive our occasional email news bulletins?

Yes!

No, thank you

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