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FACT: Jet fuel burns at 800° to 1500°F, not hot enough to melt steel (2750°F). However, experts agree that for the towers to collapse, their steel frames didn't need to melt, they just had to lose some of their structural strength — and that required exposure to much less heat. "I have never seen melted steel in a building fire," says retired New York deputy fire chief Vincent Dunn, author of The Collapse Of Burning Buildings: A Guide To Fireground Safety. "But I've seen a lot of twisted, warped, bent and sagging steel. What happens is that the steel tries to expand at both ends, but when it can no longer expand, it sags and the surrounding concrete cracks."
"Steel loses about 50 percent of its strength at 1100°F," notes senior engineer Farid Alfawak-hiri of the American Institute of Steel Construction. "And at 1800° it is probably at less than 10 percent." NIST also believes that a great deal of the spray-on fireproofing insulation was likely knocked off the steel beams that were in the path of the crashing jets, leaving the metal more vulnerable to the heat.
But jet fuel wasn't the only thing burning, notes Forman Williams, a professor of engineering at the University of California, San Diego, and one of seven structural engineers and fire experts that PM consulted. He says that while the jet fuel was the catalyst for the WTC fires, the resulting inferno was intensified by the combustible material inside the buildings, including rugs, curtains, furniture and paper. NIST reports that pockets of fire hit 1832°F.
"The jet fuel was the ignition source," Williams tells PM. "It burned for maybe 10 minutes, and [the towers] were still standing in 10 minutes. It was the rest of the stuff burning afterward that was responsible for the heat transfer that eventually brought them down."
FACT: Once each tower began to collapse, the weight of all the floors above the collapsed zone bore down with pulverizing force on the highest intact floor. Unable to absorb the massive energy, that floor would fail, transmitting the forces to the floor below, allowing the collapse to progress downward through the building in a chain reaction. Engineers call the process "pancaking," and it does not require an explosion to begin, according to David Biggs, a structural engineer at Ryan-Biggs Associates and a member of the American Society of Civil Engineers (ASCE) team that worked on the FEMA report.
ПАЗИ
FACT: "There is no scientific basis for the conclusion that explosions brought down the towers," Lerner-Lam tells PM. "That representation of our work is categorically incorrect and not in context."
The report issued by Lamont-Doherty includes various graphs showing the seismic readings produced by the planes crashing into the two towers as well as the later collapse of both buildings .
ЕВЕ ЈА СЕДМИЦАТА
There are two other possible contributing factors still under investigation: First, trusses on the fifth and seventh floors were designed to transfer loads from one set of columns to another. With columns on the south face apparently damaged, high stresses would likely have been communicated to columns on the building's other faces, thereby exceeding their load-bearing capacities.
Second, a fifth-floor fire burned for up to 7 hours. "There was no firefighting in WTC 7," Sunder says. Investigators believe the fire was fed by tanks of diesel fuel that many tenants used to run emergency generators. Most tanks throughout the building were fairly small, but a generator on the fifth floor was connected to a large tank in the basement via a pressurized line. Says Sunder: "Our current working hypothesis is that this pressurized line was supplying fuel [to the fire] for a long period of time."
WTC 7 might have withstood the physical damage it received, or the fire that burned for hours, but those combined factors — along with the building's unusual construction — were enough to set off the chain-reaction collaps
There are two other possible contributing factors still under investigation: First, trusses on the fifth and seventh floors were designed to transfer loads from one set of columns to another. With columns on the south face apparently damaged, high stresses would likely have been communicated to columns on the building's other faces, thereby exceeding their load-bearing capacities.
Second, a fifth-floor fire burned for up to 7 hours. "There was no firefighting in WTC 7," Sunder says. Investigators believe the fire was fed by tanks of diesel fuel that many tenants used to run emergency generators. Most tanks throughout the building were fairly small, but a generator on the fifth floor was connected to a large tank in the basement via a pressurized line. Says Sunder: "Our current working hypothesis is that this pressurized line was supplying fuel [to the fire] for a long period of time."
WTC 7 might have withstood the physical damage it received, or the fire that burned for hours, but those combined factors — along with the building's unusual construction — were enough to set off the chain-reaction collaps
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consulted more than 300 experts and organizations in its investigation into 9/11 conspiracy theories. The following were particularly helpful.
Air Crash Analysis
Cleveland Center regional air traffic control
Bill Crowley special agent, FBI
Ron Dokell president, Demolition Consultants
Richard Gazarik staff writer, Pittsburgh Tribune-Review
Yates Gladwell pilot, VF Corp.
Michael K. Hynes, Ed.D.,
ATP, CFI, A&P/IA president, Hynes Aviation Services; expert, aviation crashes
Ed Jacoby Jr. director,
New York State Emergency Management Office (Ret.); chairman, New York State Disaster Preparedness Commission (Ret.)
Johnstown-Cambria County Airport Authority
Cindi Lash staff writer, Pittsburgh Post-Gazette
Matthew McCormick manager, survival factors division, National Transportation Safety Board (Ret.)
Wallace Miller coroner, Somerset County, PA
Robert Nagan meteorological technician, Climate Services Branch, National Climatic Data Center
Dave Newell director, aviation and travel, VF Corp.
James O’Toole politics editor, Pittsburgh Post-Gazette
Pennsylvania State Police Public Information Office
Jeff Pillets senior writer,
The Record, Hackensack, NJ
Jeff Rienbold director, Flight 93 National Memorial, National Park Service
Dennis Roddy staff writer, Pittsburgh Post-Gazette
Master Sgt. David Somdahl public affairs officer,
119th Wing, North Dakota
Air National Guard
Mark Stahl photographer; eyewitness, United Airlines Flight 93 crash scene
Air Defense
Lt. Col. Skip Aldous (Ret.) squadron commander,
U.S. Air Force
Tech. Sgt. Laura Bosco public affairs officer,
Tyndall Air Force Base
Boston Center regional air traffic control
Laura Brown spokeswoman,
Federal Aviation Administration
Todd Curtis, Ph.D. founder, Airsafe.com; president, Airsafe.com Foundation
Keith Halloway public affairs officer, National Transportation Safety Board
Ted Lopatkiewicz director, public affairs, National Transportation Safety Board
Maj. Douglas Martin public affairs officer,
North American Aerospace Defense Command
Lt. Herbert McConnell public affairs officer,
Andrews AFB
Michael Perini public affairs officer, North American Aerospace Defense Command
John Pike director, GlobalSecurity.org
Hank Price spokesman, Federal
Aviation Administration
Warren Robak RAND Corp.
Bill Shumann spokesman,
Federal Aviation Administration
Louis Walsh public affairs officer, Eglin AFB
Chris Yates aviation security editor, analyst, Jane’s Transport
Aviation
Fred E.C. Culick, Ph.D., S.B., S.M. professor of aeronautics, California Institute of Technology
Clint Oster professor of public and environmental affairs, Indiana University; aviation safety expert
Capt. Bill Scott (Ret. USAF) Rocky Mountain bureau chief, Aviation Week
Bill Uher News Media Office, NASA Langley Research Center
Col. Ed Walby (Ret. USAF)
director, business development, HALE Systems Enterprise, Unmanned Systems, Northrop Grumman
Image Analysis
William F. Baker member, FEMA Probe Team; partner, Skidmore, Owings, Merrill
W. Gene Corley, Ph.D., P.E., S.E. senior vice president, CTL Group; director,
FEMA Probe Team
Bill Daly senior vice president, Control Risks Group
Steve Douglass image analysis consultant, Aviation Week
Thomas R. Edwards, Ph.D. founder, TREC; video forensics expert.
Ronald Greeley, Ph.D. professor of geology, Arizona State University
Rob Howard freelance photographer; WTC eyewitness
Robert L. Parker, Ph.D. professor of geophysics,
University of California, San Diego
Structural Engineering / Building Collapse
Farid Alfawakhiri, Ph.D. senior engineer, American Institute of Steel Construction
David Biggs, P.E. structural engineer, Ryan-Biggs Associates; member, ASCE team for FEMA report
Robert Clarke structural engineer, Controlled Demolitions Group Ltd.
Glenn Corbett technical editor, Fire Engineering; member, NIST advisory committee
Vincent Dunn deputy fire chief (Ret.), FDNY; author, The Collapse Of Burning Buildings: A Guide To Fireground Safety
John Fisher, Ph.D. professor of civil engineering, Lehigh University; professor emeritus, Center for Advanced Technology; member, FEMA Probe Team
Ken Hays executive vice president, Masonry Arts
Christoph Hoffmann, Ph.D. professor of computer science, Purdue University; project director, September 11 Pentagon Attack Simulations Using LS-Dyna, Purdue University
Allyn E. Kilsheimer, P.E.
CEO, KCE Structural Engineers PC; chief structural engineer, Phoenix project; expert in blast recovery, concrete structures, emergency response
Won-Young Kim, Ph.D. seismologist, Lamont-Doherty Earth Observatory, Columbia University
William Koplitz photo desk manager, FEMA
John Labriola freelance photographer, WTC survivor
Arthur Lerner-Lam, Ph.D. seismologist; director,
Earth Institute, Center for Hazards and Risk Research, Columbia University
James Quintiere, Ph.D. professor of engineering, University of Maryland member, NIST advisory committee
Steve Riskus freelance photographer; eyewitness, Pentagon crash
Van Romero, Ph.D. vice president, New Mexico Institute of Mining and Technology
Christine Shaffer spokesperson, Viracon
Mete Sozen, Ph.D., S.E. Kettelhut Distinguished Professor of Structural Engineering, Purdue University; member, Pentagon Building Performance Report; project conception, September 11 Pentagon Attack Simulations Using LS-Dyna, Purdue University
Shyam Sunder, Sc.D.
acting deputy director, lead investigator, Building and Fire Research Laboratory, National Institute of Standards and Technology
Mary Tobin science writer, media relations, Earth Institute, Columbia University
Forman Williams, Ph.D. professor of engineering, physics, combustion, University of California,
San Diego; member, advisory committee, National Institute of Standards and Technology
преку 300 експерти и организации жал ми е што глуп филм ви го пере мозокот
на вистината и науката!!!!
..тоа што се случи на 9/11 е нешто што НИ ЕДНА терористтичка организација, а која не се вика УСА, Русија.......Кина и..................толку, нема други такви...не може да го организира. 
