building7-closeup-burningAlthough Popular Mechanics states the office fires in WTC 7 reached temperatures of 1,100°F, both critics and supporters of the official story with technical expertise have pointed out that there is no evidence for fires that hot.The Popular Mechanics chapter regarding the mysterious collapse of World Trade Center 7 (WTC 7) shows itself to be no more promising than its previous chapter on the Twin Towers.

PM begins this section by summarizing the history of the controversy surrounding WTC 7 and the numerous investigations carried out regarding its collapse. PM correctly notes that many agencies were located in the building as tenants, including the Secret Service, Central Intelligence Agency, Department of Defense, Internal Revenue Service, Securities and Exchange Commission, and New York City's Office of Emergency Management.1

The chapter discusses the initial FEMA investigation and how, after FEMA failed to provide an explanation for WTC 7's collapse, the task was then handed over to NIST. PM touts the NIST report on WTC 7 as having finally proved the building was not destroyed with explosives. Contrary to PM's assertion that the reason for WTC 7's collapse is “less complicated and even more remarkable” (pg 66) than controlled demolition, it is apparent that the cause of collapse is still demolition, and that the NIST WTC 7 report utterly fails to provide a reasonable explanation of what actually caused the collapse of the building.

The first section of PM's WTC 7 chapter mainly discusses the fire and damage to WTC 7 and how this supposedly caused the building to collapse. Here is a summary of what NIST claims caused the collapse of WTC 7:

  1. The fires caused sufficient thermal expansion in the steel beams on the east side of WTC 7 to force the steel girder connecting Columns 44 and 79 to lose its connection with the latter, and to damage the floor framing on floors near Column 79.

  2. The loss of that girder's connection to Column 79, along with fire–induced damage to the floor systems around Column 79, caused Floor 13 to collapse.

  3. The collapse of Floor 13 caused all the floors below it down to Floor 5 to collapse.

  4. Column 79, being left with inadequate lateral support, buckled between Floors 5 and 14.

  5. This buckling caused the downward movement of Column 79 (which caused the collapse of the east penthouse).

  6. Columns 80 and 81, having also lost support, buckled, causing all the floors on the east side of WTC 7, which had been weakened by the fire, to collapse. . . .

  7. All the other interior columns then failed, leaving the building a hollow shell.

  8. After most of the collapse had already occurred in the building's interior, where it could not be seen from the outside, the exterior columns failed, completing the collapse.2

However, each of these points in this fantastic scenario is problematic:

  1. Though PM claims that the fires in WTC 7 reached temperatures ranging from 299°C (570°F) to 593°C (1,100°F), scientists on both sides of the argument have concluded that the fires could not have become this hot and could not have reached the temperatures claimed by NIST:

    [R]aising those five floor beams to a temperature of 600°C would require an enormous amount of energy, far more than was available from the burning of the office furnishings underneath the floor beams. — Kevin Ryan 3

    NIST's collapse initiation hypothesis requires that structural steel temperatures on floors 12/13 significantly exceeded 300°C (570°F) — a condition that could never have been realized with NIST's postulated 32 kg/m2 fuel loading. — Dr. Frank Greening 4


  2. The fire that NIST claims started the collapse (via thermal expansion of long-span beams) had actually burned out in the area of the collapse more than an hour before the collapse. It could not, therefore, have caused the collapse at 5:20 p.m., as NIST claims:

    • Around 4:45 p.m., a photograph showed fires on Floors 7, 8, 9, and 11 near the middle of the north face; Floor 12 was [entirely] burned out by this time.5

    Examination of the photographs in the Final Report shows that the fire had burned out in the area of the collapse more than an hour before the collapse.

  3. NIST arbitrarily added 10% to the result of their Fire Dynamics Simulator (FDS). This is simply not done in a scientific analysis:

    • Case A used the temperature data as obtained from the FDS simulation. Case B increased the Case A gas temperatures by 10%.6

    • Only the fire-induced damage produced by Case B temperatures was carried forward as the initial condition for the building collapse analysis.7

  4. NIST applied this arbitrarily increased temperature for 4 hours of heating, ignoring their statement that the fires lasted only 20 to 30 minutes in any location:

    • column-76Popular Mechanics repeats NIST's claim that the failure of column 79 caused the collapse of the entire building, even though the scientific evidence contradicts this theory. The building response is examined at 3.5 h and 4.0 h of heating. At 3.5 h, the floor systems had fire–induced damage and failures of some connections, beams, and girders. After 4.0 h of heating, substantially more damage and failures had occurred in the WTC 7 structural floor system, particularly in the northeast region surrounding Column 79.8

  5. NIST applied the 4 hours of heating in 1–½ seconds over the entire northeast part of the floor, again creating an unrealistic situation and result:

    • Ramping up the temperatures for the beams and the girder then commenced at 1.1 s, leveling off at temperatures of 600°C for the beams and 500°C for the girder at 2.6 s. These temperature histories were prescribed uniformly for all nodes of the beams and the girder, respectively.9

  6. NIST heated the steel beams, but not the concrete slab above, and then claimed that the temperature differential caused the shear studs to fail. In reality, the fire would have heated them both nearly uniformly — without significant differential expansion.

    • No thermal expansion or material degradation was considered for the concrete slab.10

Concrete expands at 85% the rate of steel. Leaving this expansion out of the calculations in order to show failure of the shear studs is both unscientific and fraudulent.

Certainty of impending collapse

David Ray Griffin noted in The Mysterious Collapse of WTC Seven: Why NIST's Final 9/11 Report is Unscientific and False:

[I]f NIST did engage in fraudulent science, this would not be particularly surprising. NIST is an agency of the US Department of Commerce. During the years it was writing its World Trade Center reports, therefore, it was an agency of the Bush-Cheney administration. In 2004, the Union of Concerned Scientists put out a document charging this administration with “distortion of scientific knowledge for partisan political ends.” By the end of the Bush administration, this document had been signed by over 15,000 scientists, including 52 Nobel Laureates and 63 recipients of the National Medal of Science.

Moreover, a scientist who formerly worked for NIST has reported that it has been “fully hijacked from the scientific into the political realm,” with the result that scientists work ng for NIST “lost [their] scientific independence, and became little more than ‘hired guns.'” Referring in particular to NIST's work on the World Trade Center, he said everything had to be approved by the Department of Commerce, the National Security Agency, and the Office of Management and Budget–“an arm of the Executive Office of the President,” which “had a policy person specifically delegated to provide oversight on [NIST's] work.”

Part 8: WTC 7 Wreckage Pile

1 For the full list of WTC 7 tenants, see:

2 Summary adapted from The Mysterious Collapse of World Trade Center 7, by David Ray Griffin, pg 210–211

3 Quoted from:

4 Quoted from:– GreeningCommentsNCSTAR1-9.pdf

5 NIST “L” pg 26 [pdf pg 30]

6 NIST NCSTAR 1A pg 32 [pdf pg 74] get_pdf.cfm?pub_id=861610

7 NIST NCSTAR 1A pg 36 [pdf pg 78]

8 NIST NCSTAR 1–9 Vol. 2 pg 493 [pdf pg 155]:

9 NIST NCSTAR 1–9 Vol. 1 pg 352 [pdf pg 396]

10 NIST NCSTAR 1–9 Vol. 1 pg 352 [pdf pg 396]