[quote]JustTheFacts wrote:
That’s why it’s so important that people reevaluate what really happened on 9/11…
BYU professor thinks bombs, not planes, toppled WTC
Deseret Morning News
The physics of 9/11 - including how fast and symmetrically one of the World Trade Center buildings fell - prove that official explanations of the collapses are wrong, says a Brigham Young University physics professor.
http://deseretnews.com/dn/view/1%2C1249%2C635160132%2C00.html[/quote]
Sorry JTF, but this has been disproven. The following is a good read. Although very long, it is at the same time very interesting. A panel of M.I.T. folks were involved in this.
When the Twin Towers Fell
One month after the attack on the World Trade Center, M.I.T. structural engineers offer their take on how and why the towers came down.
by Steven Ashley
weighed about 3,200,000 pounds."
Why the Towers Fell
With all of its structural redundancies, “the World Trade Center was probably one of the more resistant tall building structures,” McNamara said, adding that “nowadays, they just don’t build them as tough as the World Trade Center.” His statement is bolstered by the fact that the support structures of both twin towers withstood the initial hits of the two kamikaze airliners despite the breaching of many levels of framing. After the deletion of key structural members from about the 90th to 96th floors on the north face of the north tower, One WTC, and from about the 75th to the 84th floors of the south, east and north faces of the south tower, Two WTC, the buildings’ skeletons found alternative paths to take the loads. Each impact and following explosion imparted first a large local lateral force and then an omnidirectional force to the structures, together causing massive initial damage to the columns and floor systems at the elevation of the crash.
Despite shocks and explosions estimated to be equivalent to that of the 1995 truck bombing of the Alfred P. Murrah Federal Building in Oklahoma City (about 400 tons of TNT), the towers remained upright. “The buildings displayed a tremendous capacity to stand there despite the damage to a major portion of the gravity system, and for an hour or so they did stand there,” McNamara said. “The lateral truss systems redistributed the load when other critical members were lost. It’s a testament to the system that they lasted so long.”
Newspapers and TV newscasts reported that the twin towers had been designed to withstand a collision with a Boeing 707. The events of September 11th show that this was indeed the case. “However, the World Trade Center was never designed for the massive explosions nor the intense jet fuel fires that came next?a key design omission,” stated Eduardo Kausel, another M.I.T. professor of civil and environmental engineering and panel member. The towers collapsed only after the kerosene fuel fire compromised the integrity of their structural tubes: One WTC lasted for 105 minutes, whereas Two WTC remained standing for 47 minutes. “It was designed for the type of fire you’d expect in an office building?paper, desks, drapes,” McNamara said. The aviation fuel fires that broke out burned at a much hotter temperature than the typical contents of an office. “At about 800 degrees Fahrenheit structural steel starts to lose its strength; at 1,500 degrees F, all bets are off as steel members become significantly weakened,” he explained.
Some have raised questions about the degree of fire protection available to guard the structural steel. According to press reports, the original asbestos cementitious fireproofing applied to the steel framework of the north tower and the lower 30 stories of the south were removed after the 1993 terrorist truck bombing.
Others have pointed out the possibility that the aviation fuel fires burned sufficiently hot to melt and ignite the airliners’ aluminum airframe structures. Aluminum, a pyrophoric metal, could have added to the conflagrations. Hot molten aluminum, suggests one well-informed correspondent, could have seeped down into the floor systems, doing significant damage. "Aluminum melts into burning ‘goblet puddles’ that would pool around depressions, [such as] beam joints, service openings in the floor, stair wells and so forth…The goblets are white hot, burning at an estimated 1800 degrees Celsius. At this temperature, the water of hydration in the concrete is vaporized and consumed by the aluminum. This evolves hydrogen gas that burns. Aluminum burning in concrete produces a calcium oxide/silicate slag covered by a white aluminum oxide ash, all of which serve to insulate and contain the aluminum puddle. This keeps the metal hot and burning. If you look at pictures of Iraqi aircraft destroyed in their concrete shelters [during the Persian Gulf war], you will notice a deep imprint of the burned aircraft on the concrete floor.
Though the Boeing 767s airliners that hit the towers were somewhat larger than the Boeing 707 (maximum takeoff weights: 395,000 pounds versus 336,000 pounds) the structures were designed to resist, the planes carried a similarly sized fuel load as the older model?about 24,000 gallons versus 23,000 gallons, according to Kausel. “Most certainly,” he continued, “no building has or will resist this kind of fire.” The sprinkler system, which was probably compromised, would have been are useless against this kind of fire, he said, adding, “The World Trade Center towers performed admirably; they stood long enough for the majority of the people to be successfully evacuated.”
Kausel also reported that he had made estimates of the amount of energy generated during the collapse of each tower. “The gravitational energy of a building is like water backed up behind a dam,” he explained. When released, the accumulated potential energy is converted to kinetic energy. With a mass of about 500,000 tons (5 x 108 kilograms), a height of about 1,350 ft. (411 meters), and the acceleration of gravity at 9.8 meters per second 2, he came up with a potential energy total of 1019 ergs (1012 Joules or 278 Megawatt-hours). “That’s about 1 percent of the energy released by a small atomic bomb,” he noted.
The M.I.T. professor added that about 30 percent of the collapse energy was expended rupturing the materials of the building, while the rest was converted into the kinetic energy of the falling mass. The huge gray dust clouds that covered lower Manhattan after the collapse were probably formed when the concrete floors were pulverized in the fall and then jetted into the surrounding neighborhood. “Of the kinetic energy impacting the ground, only 0.1 percent was converted to seismic energy,” he stated. “Each event created a (modest-sized) magnitude 2 earthquake, as monitored at Columbia University’s Lamont-Doherty Observatory, which is located about 30 kilometers away from New York City.” Kausel concluded that the “the largest share of the kinetic energy was converted to heat, material rupture and deformation of the ground below.”
Despite the expert panel’s preliminary musings on the failure mechanisms responsible for the twin towers’ fall, the definitive cause has yet to be determined. Reportedly, the National Science Foundation has funded eight research projects to probe the WTC catastrophe. The American Society of Civil Engineers is sponsoring several studies of the site. Meanwhile the Structural Engineering Institute of the American Society of Structural Engineers has established an investigative team to analyze the disaster and learn from the failure. W. Gene Corley, senior vice president of the Construction Technology Laboratory in Skokie, Ill., is said to be heading the ASSE study team through its initial phase of data gathering, and then William Baker, a structural engineer at the Chicago-based firm of Skidmore Owings & Merrill in Chicago, will lead the following analysis phase. The Structural Engineering Institute is to partner with the American Institute of Steel Construction, the National Fire Protection Association and the Society of Fire Protection Engineers. The Federal Emergency Management Agency has been invited to join as well.
How the Towers Fell
Given the lack of firm conclusions regarding how the collapses occurred, the M.I.T. panel participants asked their audience to consider various theories they put forth. In general, it was agreed that as the structure warped and weakened at the top of each tower, the frame, along with the concrete slabs, furniture, file cabinets and other materials, became an enormous consolidated weight that eventually crushed the lower portions of the structure below. The details of how the frame members failed remain under contention.
Professor Connor’s theory focused on weaknesses in how the vertical and horizontal structural members were tied together. During construction, he explained, each prefabricated floor system was lifted into place by a crane and “supported at the ends like a hinge, where they were bolted and welded to the inner and outer framing tubes” so that part of the gravity load went through the core and the other part through the exterior structure. “The floor trusses sat on beams and were tied down so the core was locked to the exterior,” he said. “It was an unusual system and very lightweight. If you lose the connection between them, however, you lose the ability to carry the floor loads and allow the floors to slide back and forth under stress. If a damaged floor system were to fall, it would break the end connections in the lower floors and down and down the floors would go.”
“In my theory, the hot fire weakened the supporting joint connection,” Connor continued. “When it broke, one end of a floor fell, damaging the floor system underneath, while simultaneously tugging (pulling) the vertical members to which it was still attached toward the center of the building and down.” This phenomenon started a parasitic process that accelerated until total failure and the structure fell in on itself, he said.
Eduardo Kausel proposed an alternative failure explanation that he acknowledged was independently developed by Zdenek Bazant, a professor at Northwestern University. “I believe that the intense heat softened or melted the structural elements?floor trusses and columns?so that they became like chewing gum, and that was enough to trigger the collapse,” he said. “The floor trusses are likely to have been the first to sag and fail. As soon as the upper floors became unsupported, debris from the failed floor systems rained down onto the floors below, which eventually gave way, starting an unstoppable sequence. The dynamic forces are so large that the downward motion becomes unstoppable.”
Via two simple models, Kausel was able to determine that the fall of the upper building portion down onto a single floor must have caused dynamic forces exceeding the buildings? design loads by at least an order of magnitude. He also performed some computer simulations that indicate the building material fell almost unrestricted at nearly the speed of free-falling objects. “The towers’ resistive systems played no role. Otherwise the elapsed time of the fall would have been extended,” he noted. As it was, the debris took about nine seconds to reach the ground from the top.
“It’s difficult to judge which of these failure mechanisms occurred first; probably all occurred and interacted,” said panel member Oral Buyukozturk, professor of civil and environmental engineering at M.I.T.. “The prolonged effect of high heat is likely to have led to the buckling of the columns, collapse of the floors, as well as to the shearing of the floors upon the failure the joints.” He noted that videotapes of the catastrophe showed some tilting of the top portion of the south tower before it collapsed. “This indicates the buckling of one building face while the adjacent face was bending [placed into tension].” After that, the upper portions of the tower are shown disintegrating, with “a dynamic effect and amplification process” following that led to a progressive collapse?“a kind of pancaking or deck of cards effect”?down to ground zero, Buyukozturk stated.
Kausel addressed the oft-asked question of why the towers did not tip over like a falling tree. “A tree is solid, whereas building is mostly air or empty space; only about 10 percent is solid material. Since there is no solid stump underneath to force it to the side, the building cannot tip over. It could only collapse upon itself.” Robert McNamara said his failure mechanism theory “focuses on the connections that hold the structure together,” but he cautioned that “we really need to wait for a detailed investigation, before we decide if we have to up the code ratings for these connections in signature structures.”
More from folks smarter than us.
http://architecture.about.com/library/weekly/aawtc-collapse.htm
[quote]
BYU Professor Has Plenty of Company in the Academic Community, Including 60 Faculty Members from Two Utah Universities who Concur a Controlled Demolition Most Likely Brought Down the WTC and Further Investigation Is Needed
Sounds like these folks know what the hell their talking about.
http://www.thenewamerican.com/artman/publish/article_1253.shtml
Demolition charges. “The planes did not bring those towers down; bombs did. So why use planes? It seems they were a diversionary tactic ? a grand spectacle.” So writes Randy Lavello in an article on www.prisonplanet.com, one of the Internet sites of shortwave radio broadcaster and video producer Alex Jones.
“The World Trade Center was not destroyed by terrorists. It was a controlled demolition, an inside job!” says “Geronimo Jones” in an article on the Internet site letsroll911.org.
“The fact that the towers fell this quickly (essentially at the rate of free-fall) is conclusive evidence that they were deliberately demolished,” he claims.
This is also a major theme of the vonKleist video, 911 In Plane Site, which, like a number of other video productions, attempts to liken the World Trade Center collapses to the 1995 attack on Oklahoma City’s Alfred P. Murrah Federal Building. Some of these 9/11 productions even cite Gen. Partin as an authority to back their theories about the Twin Towers. General Partin exposed the evidence that the OKC blast included internal demolition charges, in addition to the Ryder truck bomb.
But Partin says the OKC and WTC incidents are completely different. The Murrah building was only nine stories tall and made of heavy steel-reinforced concrete. And, since the Ryder truck was outside the building, the damage it caused was primarily from the shock wave of pressurized air. The Twin Towers, on the other hand, were 110 stories tall, supported by steel columns, and the planes ? which served as missiles ? dumped large quantities of high-energy, hot fuel.
“The claims that the explosions and fires would not have generated enough heat to cause the building to collapse are nonsense,” Partin told THE NEW AMERICAN. “Steel doesn’t have to ‘melt’ as some of these people claim. The yield strength of steel drops very dramatically under heat, and the impact of the airliners would have severely impacted the support columns. When they could no longer support the upper stories and the top started coming down, the dynamic loading caused a very rapid collapse, or ‘pancaking,’ that would have very nearly approached free-fall rate. No demolition charges were needed to accomplish this.”
Edward Peik, vice president of Alpine Environmental, Inc. of Chelmsford, Mass., agrees. Peik, a civil engineer, with 40 years of engineering experience in government and industry, grew up in New York City and is familiar with the structure of the Twin Towers. “I was at home watching all of this unfold on TV” on 9/11, he told The New American. “My first reaction was, ‘My God, they’ve got to get everybody out of there right away, because it’s going to come down fast!’ I called my son Ron, who is also an engineer. We were both beside ourselves because we knew that they wouldn’t stay up very long. As soon as fire hits steel, it loses strength fast and those towers had relatively lightweight steel beams spanning large distances. The building was supported by the steel outer walls. When the upper part of the building started coming down, the floors below could not support the weight crashing down on them. It was a vertical domino effect.”
The opinions of Partin, Peik, and several other structural experts we consulted agree with the official consensus that the WTC towers collapsed as a result of the severe damage caused by the planes and the ensuing fires, not as a result of controlled demolition. General Partin says that he was contacted by vonKleist, who wanted him to support his position, which Partin was not willing to do.
This article does a pretty good job of debunking some of the myths as well
http://www.popularmechanics.com/science/defense/1227842.html?page=4&c=y
THE WORLD TRADE CENTER
The collapse of both World Trade Center towers–and the smaller WTC 7 a few hours later–initially surprised even some experts. But subsequent studies have shown that the WTC’s structural integrity was destroyed by intense fire as well as the severe damage inflicted by the planes. That explanation hasn’t swayed conspiracy theorists, who contend that all three buildings were wired with explosives in advance and razed in a series of controlled demolitions.
Widespread Damage
CLAIM: The first hijacked plane crashed through the 94th to the 98th floors of the World Trade Center’s 110-story North Tower; the second jet slammed into the 78th to the 84th floors of the 110-story South Tower. The impact and ensuing fires disrupted elevator service in both buildings. Plus, the lobbies of both buildings were visibly damaged before the towers collapsed. “There is NO WAY the impact of the jet caused such widespread damage 80 stories below,” claims a posting on the San Diego Independent Media Center Web site (sandiego.indymedia.org). “It is OBVIOUS and irrefutable that OTHER EXPLOSIVES (… such as concussion bombs) HAD ALREADY BEEN DETONATED in the lower levels of tower one at the same time as the plane crash.”
FACT: Following up on a May 2002 preliminary report by the Federal Emergency Management Agency (FEMA), a major study will be released in spring 2005 by the National Institute of Standards and Technology (NIST), a branch of the U.S. Department of Commerce. NIST shared its initial findings with PM and made its lead researcher available to our team of reporters.
The NIST investigation revealed that plane debris sliced through the utility shafts at the North Tower’s core, creating a conduit for burning jet fuel–and fiery destruction throughout the building. “It’s very hard to document where the fuel went,” says Forman Williams, a NIST adviser and a combustion expert, “but if it’s atomized and combustible and gets to an ignition source, it’ll go off.”
Burning fuel traveling down the elevator shafts would have disrupted the elevator systems and caused extensive damage to the lobbies. NIST heard first-person testimony that “some elevators slammed right down” to the ground floor. “The doors cracked open on the lobby floor and flames came out and people died,” says James Quintiere, an engineering professor at the University of Maryland and a NIST adviser. A similar observation was made in the French documentary “9/11,” by Jules and Gedeon Naudet. As Jules Naudet entered the North Tower lobby, minutes after the first aircraft struck, he saw victims on fire, a scene he found too horrific to film.
“Melted” Steel
CLAIM: “We have been lied to,” announces the Web site AttackOnAmerica.net. “The first lie was that the load of fuel from the aircraft was the cause of structural failure. No kerosene fire can burn hot enough to melt steel.” The posting is entitled “Proof Of Controlled Demolition At The WTC.”
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.”
Puffs Of Dust
CLAIM: As each tower collapsed, clearly visible puffs of dust and debris were ejected from the sides of the buildings. An advertisement in The New York Times for the book Painful Questions: An Analysis Of The September 11th Attack made this claim: “The concrete clouds shooting out of the buildings are not possible from a mere collapse. They do occur from explosions.” Numerous conspiracy theorists cite Van Romero, an explosives expert and vice president of the New Mexico Institute of Mining and Technology, who was quoted on 9/11 by the Albuquerque Journal as saying “there were some explosive devices inside the buildings that caused the towers to collapse.” The article continues, “Romero said the collapse of the structures resembled those of controlled implosions used to demolish old structures.”
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.
Like all office buildings, the WTC towers contained a huge volume of air. As they pancaked, all that air–along with the concrete and other debris pulverized by the force of the collapse–was ejected with enormous energy. “When you have a significant portion of a floor collapsing, it’s going to shoot air and concrete dust out the window,” NIST lead investigator Shyam Sunder tells PM. Those clouds of dust may create the impression of a controlled demolition, Sunder adds, “but it is the floor pancaking that leads to that perception.”
Demolition expert Romero regrets that his comments to the Albuquerque Journal became fodder for conspiracy theorists. “I was misquoted in saying that I thought it was explosives that brought down the building,” he tells PM. “I only said that that’s what it looked like.”
Romero, who agrees with the scientific conclusion that fire triggered the collapses, demanded a retraction from the Journal. It was printed Sept. 22, 2001. “I felt like my scientific reputation was on the line.” But emperors-clothes.com saw something else: “The paymaster of Romero’s research institute is the Pentagon. Directly or indirectly, pressure was brought to bear, forcing Romero to retract his original statement.” Romero responds: “Conspiracy theorists came out saying that the government got to me. That is the farthest thing from the truth. This has been an albatross around my neck for three years.”