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NIST Final Report on the Collapse of the World Trade Center Towers, Sept. 2005
Part I: Sept 11, 2001
PDF page numbers: pp.51-96 corresponding to NIST page numbers: 1-46

chapter 1: NYC's World Trade Center

1. who were the architects and structural engineers for the WTC?
2. How many buildings comprise the WTC complex as of 2001?
3. How many levels were below grade and how deep was the excavation to bedrock?
4. Which airliner and speed of impact was considered in the structural design of the WTC?
5. What was the original purpose of the "hat truss" at the 107th floor of the WTC towers?
6. Describe the fireproofing used for columns and trusses in the WTC.
7. Describe the fireproofing used for core stairwells.
8. How much floor area were the sprinklers designed for?
9. Describe the alarm system in the WTC.
10. Is there any evidence that a fire caused by jet fuel was considered in the design of the WTC? Would such a consideration now be required by code?
11. Describe the "geometry" of egress stairs within the building core. In other words, how and why did the stairs move around in plan and section?

1. what is the length and wingspan of the Boeing 767-200ER that crashed into WTC 1?
2. how much jet fuel was probably on board when the jet hit tower #1?
3. Describe the damage done to the 94th floor of tower #1 due to the impact of the jet (i.e., within the first 0.7 seconds after impact).
4. Why were sprinklers not working?
5. According to NIST, would the buildings have remained standing if the fire was controlled?
6. What percentage of the 10,00 gallons of jet fuel initially burned inside the building?
7. How long did it take for people below the impact floors to descend 10 floors from their original location? How long did it take before 90% of the survivors had left the building?
8. How many occupants were able to escape from WTC 1?

1. What announcements were made at 9:00 and 9:02 am that caused some confusion in the evacuation of WTC 2?
2. How many exterior and core columns were severed in the first 0.6 seconds after impact?
3. How many egress stairs were still passable after impact?
4. What caused some exterior columns to begin bowing inward?

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