destruction of the twin towers n.
Skip this Video
Loading SlideShow in 5 Seconds..
Destruction of the Twin Towers PowerPoint Presentation
Download Presentation
Destruction of the Twin Towers

Destruction of the Twin Towers

161 Vues Download Presentation
Télécharger la présentation

Destruction of the Twin Towers

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Destructionof the Twin Towers

  2. The Event

  3. AA-11 & UA175 Flight Paths The Event Alleged flight paths (lost to radar for part of trip)

  4. The Event

  5. AA-11 Impact on WTC-1 The Event One landing gear

  6. The Event

  7. UA-175 Impact on WTC-2 The Event Landing gear, engine, fuselage section

  8. The Stage

  9. The Buildings: Layout World Trade Center Building 7 N North Tower South Tower

  10. The Buildings: Heights World Trade Center N 110 stories 47 stories

  11. Columns WTC 1-2 Construction 47 central core columns, 244 perimeter columns

  12. in Progress WTC 1-2 Construction Basement, first 10 floors of WTC1

  13. 47 Central Core Columns WTC 1-2 Construction 14”x36” near bottom, various smaller forms near top

  14. 244 Perimeter Columns WTC 1-2 Construction Truss mounting points Diagonal- brace mounting points 3-column-3-floor assemblies alternating across 3 floors, connected by welded/bolted spandrel plates

  15. WTC 1-2 Destruction Features Perimeter cross-link strength Acting like a Roman arch over the hole

  16. Floor Support Trusses WTC 1-2 Construction

  17. Floor Support Trusses WTC 1-2 Construction Perimeter column loops stick up into grooves on metal deck, act as shear studs Core column Main trusses: these were double

  18. Floor Support Trusses WTC 1-2 Construction Transverse truss: at right angles to main trusses

  19. “Hat” Truss WTC 1-2 Construction Floors 106-110: Helps spread stress forces within core and between core and perimeter, and supports communications tower on top

  20. The Reports

  21. The Reports • FEMA -- 2002 • 9/11 Commission -- 2004 • NIST: National Institute of Science and Technology -- 2005

  22. FEMA Investigation/Report • Carried out by “volunteers” from the American Society of Civil Engineers • Bush administration agency (Katrina) • Headed by man who headed Okla.City bombing study • No “authority to impound pieces of steel before they were recycled” • No subpoena powers -- couldn’t get blueprints • “The ‘official investigation’ blessed by FEMA ... is a half-baked farce that may already have been commandeered by political forces whose primary interests, to put it mildly, lie far afield of full disclosure” -- Fire Engineering Magazine • Basic theory: Impact and fire caused a “pancake” collapse • Report+comment:

  23. FEMA Investigation/Report Conclusion: Pancaking (PBS)

  24. 9/11 Commission Report • Chairmen: "fullest possible account of the events surrounding 9/11.” • Provided intensely detailed description of situation in buildings and actions of emergency personnel • Mentioned that the buildings collapsed (period)

  25. NIST Report

  26. Problems with NIST Report • Institutional -- NIST was politicized • Coverage -- Only covered what they claim happened up until the beginning of “collapse;” virtually no analysis of what “inevitably” then happened -- wasn’t part of their assignment • Evidence -- Used questionable computer model, used little (and ignored) real evidence • Reality -- the “collapse” displayed too many features inconsistent with a gravity-driven model.

  27. NIST Problems:Institutional NIST had become “fully hijacked from the scientific into the political realm...scientists lost scientific independence and became little more than ‘hired guns.’...By 2001, everyone in NIST leadership had been trained to pay close heed to political pressures... Everything that came from the hired guns was by then routinely filtered through the front office and assessed for political implications before being released,” and was also scrutinized by the NSA, OMB, and the Commerce Department headquarters. -- whistleblower (former NIST employee)

  28. So, what did NIST say?

  29. NIST’s approach A Computer Model (ignored much physical evidence)

  30. NIST: Computer model approach • Set up three scenarios with assumptions representing different degrees of damage • See which one creates collapse • If none do, tweak the worst one further and divorce it further from empirical evidence by denigrating that evidence. • Example: South damage range was 3-10 damaged columns, only using 10 did job

  31. NIST: Computer model approach • "Upon a preliminary examination of the middle case, it became clear that the towers would likely remain standing...[so] the most severe case ... was used for the global analysis of each tower.”-- NIST Final Report • "To the extent the [severe-case] simulations deviated from the photographic evidence or eyewitness reports, the investigators adjusted the input.” -- NIST

  32. NIST: Computer model approach • "[A] fundamental problem with using computer simulation is the overwhelming temptation to manipulate the input data until one achieves the desired results. Thus what appears to be a conclusion is actually a premise... NIST tweaked the input and the buildings feel down”-- architect Eric Douglas

  33. NIST’s sequence • Plane impact • Severed some core columns • Removed fireproofing from most core columns and much of floor-supporting trusses • Fires created tremendous heat • weakened core columns • Caused floor trusses to weaken and sag, pulling in the perimeter columns, reducing peripheral support • Global collapse commenced • Top of tower above damage acted as pile driver • Floors below couldn’t resist • Out of thousands of pages, they only devoted a paragraph to this, with no indication of analysis of the process

  34. NIST: Severed Core Columns • North: 6 severed, South: 10 -- but: • North hit higher, where columns weaker • Only engines capable of such damage, but North hit head on, South off to side, so should have been other way around • There is no actual visual record • All NIST has is a computer model • Only 256 pieces of steel out of thousands saved

  35. NIST: About that steel... • NIST, 2003: "adequate for purposes of the Investigation. Regions of impact and fire damage were emphasized in the selection of steel for the Investigation.”andsteel analysis "includes...estimating the maximum temperature reached by available steel."BUT • NIST, 2005: Steel is merely “sufficient for determining quality and mechanical properties”

  36. NIST: Fire weakens steel Fire Retardant • Fire retardant coating good for 2 hours • So have to assume massive dislodging of fire retardant by impact. • NIST: of 47 core columns, FR dislodged on 43 in North, 39 in South. How know? • No evidence, just 15 shotgun blasts at flat plates (not beams) in a plywood box.

  37. NIST: Fire weakens steel Temperature Behavior • Building is an interconnected grid of thousands of tons of steel • Steel conducts heat (though not ideal) • Therefore, building sucks heat away from any place that has heat locally applied to it • Therefore, it takes a LONG time before steel temperature reaches local air temperature. • But jet fuel was consumed within 15 minutes, and office fires tend to burn out in any one area after about 20 minutes.

  38. NIST: Fire weakens steel Temperature claims • Model: 1000°C only 15-20 mins in any one place, otherwise 500°C • NIST: physical evidence indicates max temp of any steel (not necessarily columns) was 600°C • NIST: examination of perimeter steel indicated max was 250°C • Core had less oxygen than perimeter, so likely not as hot, and no evidence that it actually did get that hot • Structural steel begins to soften at 425°C • Kinda problematic for a claim of weakened columns

  39. NIST: Fire weakens steel Floor trusses sag • Basic idea (I’ve seen two quoted) • Sagging pulls in the perimeter columns • Sagging doesn’t pull in the perimeter columns, but when they cool and contract, that happens • Were they trusses or girders?

  40. NIST: Fire weakens steel Floor trusses sag

  41. NIST: Fire weakens steel Floor trusses sag • (Creep note: happens at ~30% of melting point, in this case ~920°C, so shouldn’t have happened) • Sag per model: w/creep: 44”, w/out creep: 24” • Problem: NIST paid UL $250K to test truss behavior, max deflection was 4” • NIST: UL tests weren’t representative, all had fireproofing • Actually, all had LESS fireproofing than build specs • This is a complex issue, and I’ve seen a lot of different takes on it.

  42. NIST: Fire weakens steel Sagging trusses pull wall inward

  43. NIST: Fire weakens steel Sagging trusses pull wall inward

  44. Non-NIST Observation Sagging floors? Trouble is, the floors at the perimeter walls could not have sagged if the trusses were able to pull in the walls.

  45. Let’s get technical ! • for NIST’s “pile driver” to cause collapse? • to expand the large, fast dust clouds? • to throw heavy beams fast and far? Was there ENOUGH ENERGY available from a GRAVITY DRIVEN collapse

  46. Let’s get technical ! Mind-numbing analytical details and calculations moved to the end of the presentation, where they may never be seen again . . .

  47. So we got technical ! And guess what? There was notENOUGH ENERGY available for any of these theories or observations: • NIST’s “pile driver” theory of collapse • expansion of the large, fast dust clouds • Heavy columns thrown far and fast

  48. If gravity didn’t have what it takes,What did?

  49. TheAlternativeTheory

  50. The Alternative Theory:Definition Controlled Demolition the bringing down of a building by the use of explosives/incendiaries to simultaneously remove critical supporting structure