8:46am - The first American Airlines plane hit the North Tower of the World Trade Center. McNamara said that this concept was now somewhat discredited, as similar refuges in the WTC would not have ultimately saved anyone. Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. They were probably powerful enough to blow out an entire section of each building. Explore our digital archive back to 1845, including articles by more than 150 Nobel Prize winners. Continue reading with a Scientific American subscription. I presume that this is what happened within the Twin Towers, and that the molten aluminium then began to run down into the floors below. They were the hub of the bustling Financial District, a top tourist attraction and a symbol of America. "Both scientific experiments and 250 reported disasters suffered by the aluminium industry have shown that the combination of molten aluminium and water releases enormous explosions," says Simensen. As many as 200 people fell from the Twin Towers to their deaths on 9/11 The man, one of as many as 200 victims of the attack known as 'jumpers', had chosen to escape the fire and smoke of the. However the site changed its name to the World Trade Center Site after New York mayor Michael Bloomberg urged the city to rename the site. Content on this website is for information only. The latter consideration concerns not only structural integrity but also "requires developing an acceptable comfort level for the occupants" by avoiding too much swaying. The materials along the track of the collision must also have burned. Feb. 26, 1993, Arab terrorists packed a truck with explosives and drove it into the Trade Centers cavernous basement parking garage. The buildings withstood the impact, but their steel cores were undermined by the intense heat of the burning fuel. Opposition to lateral motion is controlled by "the design's structural mass [weight], the stiffness of its lateral members and the degree of structural damping employed," Fowler said. To handle these immense forces, the engineers "designed the World Trade Center essentially as a large beam section," explained another panel member, Robert McNamara, president of the engineering firm McNamara and Salvia. More than 2,800 lives were lost with them leaving an irreparable hole in the heart, soul and skyline of Gotham. Browse 368 twin towers silhouette stock photos and images available, or start a new search to explore more stock photos and images. Click here to get The Sun newspaper delivered for FREE for the next six weeks. To do so successfully means boosting a building's structural redundancythe provision of additional means to assist system function. "The towers' resistive systems played no role. Reportedly, the National Science Foundation has funded eight research projects to probe the WTC catastrophe. Some have raised questions about the degree of fire protection available to guard the structural steel. panel participants asked their audience to consider various theories they put forth. "However, the World Trade Center was never designed for the massive explosions nor the intense jet fuel fires that came nexta key design omission," stated Eduardo Kausel, another M.I.T. The morning of Tuesday, September 11 was fine and sunny, with New Yorkers navigating the manic rush-hour commute to work or school under a cloudless blue sky. The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by the militant Islamic extremist network al-Qaeda against the United States on Tuesday, September 11, 2001. Once high temperatures weakened the towers' supporting steel structures, it was only a matter of time until the mass of the stories above initiated a rapid-sequence "pancaking" phenomena in which floor after floor was instantly crushed and then sent into near free fall to the ground below. Significantly, the panel stated that any mitigating reinforcements and redundancies added to these buildings could have only delayed the inevitable failure, though they would have bought more time for the evacuation of the occupants. Simensen continues: "I regard it as extremely likely that it was these explosions that made the skyscrapers collapse by tearing out part of the internal structure, and that this caused the uppermost floors of the buildings to fall and crush the lower parts. LICENSE TYPE. professor of civil and environmental engineering and panel member. They excavated more than 1.2 million cubic yards of earth, which were used to create 23.5 acres of land along the Hudson todays Battery Park City. Another 200,000 people visited daily. The National 9/11 Memorial & Museum opened on September 11, 2011, at the original World Trade Center site in time for the 10th anniversary of the attacks. ScienceDaily. "The best we can do is to ensure that it will stand long enough for all the people to escape." It's a testament to the system that they lasted so long.". Businessmen who would be forced to relocate protested in the streets and in court. Though the recent "disaster couldn't be envisioned as a design scenario in the 1970s, it means we have to change the way we design and construct tall buildings in the future," Buyukozturk said. Towers Falling . 9:03am - Just 20 minutes later, a second plane crashed into the South Tower. The first American Airlines Boeing 767 Flight 11 crashed into the north tower of the World Trade Center at 8:45am at a speed of 466mph (790km/h). ISBN-13. 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. It has been 17 years since the devastating 9/11 attacks. Knowledge awaits. "It was designed for the type of fire you'd expect in an office buildingpaper, desks, drapes," McNamara said. If my theory is correct, tonnes of aluminium ran down through the towers, where the smelt came into contact with a few hundred litres of water. Both large and small clumps of particles have since been found embedded in the walls of these buildings. After first describing the highly redundant structural system that kept the 110-story twin towers standing for decades despite hurricane-force winds and a terrorist truck bomb, the engineers then delineated how that system was breached and finally overcome on that fateful day when America was attacked. Aluminum, a pyrophoric metal, could have added to the conflagrations. The south tower succumbed first spewing thick clouds of dust and soot and tons of concrete, steel and glass as it crumbled. All told, they would have 15 million square feet of floor space. The centrepiece is One World Trade Center which now rises even higher than the Twin Towers at 1,776 feet tall. Kausel pointed out problems with the twin towers' emergency communications systems ("just when coordination was most critical, the people didn't know what to do"), the emergency illumination system and protection against smoke ("the great killer in building fires is smoke inhalation"). McNamara opined that the position of impact seems significant. The aviation fuel fires that broke out burned at a much hotter temperature than the typical contents of an office. 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. On the morning of Tuesday, September 11, 2001, 19 Islamic terrorists hijacked four planes in a coordinated attack on US soil. Panel members discussed providing improved fire protection for the structural elements, alternative load paths to stand in for damaged structures and fixing diaphragm floor beams more strongly to vertical members. Taking less than an hour to burn, the south tower collapsed in a massive cloud of dust and smoke. ", "How could explosions in the centre of a building cause a whole tower to collapse? We pay for videos too. Its twin collapsed soon after. Royalty-free. This configuration created a complete exterior tube around the building and a center tube down the middle. The term is used to describe the site of a nuclear explosion and later was used to refer to the point of any dramatic or violent event. "Why should we believe your alternative theory rather than the official explanation? The names of all 2,996 victims are engraved on the 152 bronze panels surrounding the pools, arranged by where individuals were on the day of the attacks, so coworkers and people on the same flight are remembered together. New theory explains collapse of World Trade Center's Twin Towers. But the towers survived. "The Sun", "Sun", "Sun Online" are registered trademarks or trade names of News Group Newspapers Limited. The expert panel then turned its attention to changes for future tall structures in the wake of what has been learned. One hour later, WTC2. 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. Two of the planes were flown into. Coverage of the American Airlines flight 11 tragedy during which nearly 3,000 perished was the main priority that day for most Western news agencies (the scenes of the twin towers collapsing were witnessed by an estimated two billion people - a third of the human race). This keeps the metal hot and burning. At the bottom, the columns are much heavier and stronger and so they would have taken a much larger load." From other disasters and experiments carried out by the aluminium industry, we know that reactions of this sort lead to violent explosions. DATE RANGE. October 2001 Length. IMAGE . ", "Yes, as a matter of fact it could. Video Unavailable. 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. One lesson is that we could develop means of rapidly emptying sprinkler systems in the floors under the point of impact. Discover world-changing science. Given that the amount of aluminium involved was large in comparison with the quantity of water, and since rust was probably also present, I believe that it is highly likely that the building collapsed as a result of a series of extremely energy-rich aluminium-water explosions. The election of Rockefellers brother Nelson as New York governor in 1959 gave the plan the political clout and momentum needed. 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). The only research that comes close to being an official account is buried deep in an appendix of the huge report into why the towers collapsed, conducted by the National Institute for Standards. . The Freedom Tower, also on the original World Trade Center site, opened in November 2014. It was in the morning New York time on September 11, 2001, when two Boeing 767 passenger planes flew into the World Trade Center's "Twin Towers" in Manhattan in New York. Helpful . At any rate, the building caught fire, which got out of control. The 47-storey third tower, located 110 meters (350 feet) away from the World Trade Centre, collapsed seven hours after the twin towers. After all, the World Trade Center was retrofitted with 10,000 viscoelastic dampers to reduce its swaying, so safety improvements can't be ignored. "There will never be a building that won't fall," Kausel noted. The late Seattle-based architect Minoru Yamasaki designed the World Trade Center. Experiments could also be carried out to find out whether fuel tanks are cut cleanly when they plough through a network of steel beams at a speed of 800 kilometres an hour. ScienceDaily, 21 September 2011. Annotation. Evidence, he says, of the biggest cover-up . The whole surface, including all its pores, is covered by the material that they carry along. "The floor trusses are likely to have been the first to sag and fail. ground zero. Called structural tubes in the business, each twin tower was strongly framed in structural steel. Connor offered that one would "need graduate-level engineering training to choose the prime target location.". When his plan was unveiled in 1964, critics cried foul, complaining that the silvery twin monoliths would destroy New Yorks skyline, ruin TV reception and severely strain city services. It consists of two reflecting pools with waterfalls rushing down where the Twin Towers once rose into the sky. Back when the WTC was built, no one seems to have anticipated the need to evacuate an entire large building at once. A lively discussion then ensued about whether the terrorist pilots knew where to hit the buildings for maximum effect. You can WhatsApp us on 07423 720 250. Christina Asquith. This evolves hydrogen gas that burns. Given the lack of firm conclusions regarding how the collapses occurred, the M.I.T. In 1962, architect Minoru Yamasaki of Troy, Michigan was picked to design the project in collaboration with Emery Roth & Sons of New York. They were the hub of the bustling Financial District, a top tourist attraction and a symbol of America. Two of the planes were flown into the Twin Towers of the World Trade Center in New York City while the others went to Washington DC and Pennsylvania. What we know is that these drag material with them on their way through the soil layer. Read more. NASA's Moon-Bound Megarocket Will Send a Spacecraft to an Asteroid, Too, 'Portable Oasis' Extracts Water from Dry Desert Air. ScienceDaily. "I believe that it is overwhelmingly probable that the theories regarding the cause of the collapse of WTC1 and WTC2 are wrong, but that the report very likely came to the correct conclusion as regards WTC7," says Simensen. Explosive meeting of molten aluminium and water. 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. ", "WTC7 may have taken more of these impacts than the other buildings. The Freedom Tower, also on the original World Trade Center site, opened in November 2014. A year later, engineers John Skilling and Leslie Robertson were chosen as the builders. In order to build the towers, engineers needed to dig down 70 feet to reach bedrock. The memorial Reflecting Absence" sits outside the museum in an eight-acre park. "Of the kinetic energy impacting the ground, only 0.1 percent was converted to seismic energy," he stated. For other inquiries Contact Us. They disagree with the investigation done by the US National Institute of Standards and Technology . The Sun website is regulated by the Independent Press Standards Organisation (IPSO), Pictures of the collapse of the Twin Towers are some of the most iconic in history, The memorial to those killed sits in the shadow of the One World Trade Center, which replaced the Twin Towers, Incredible images show Americas heroes trying to save lives on September 11, Independent Press Standards Organisation (IPSO). ", "Would it be possible to perform scientific experiments that can support your theory? 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. "Though the twin towers were not much taller than their famous uptown predecessor, the Empire State Building, the World Trade Center rose during the late 1960s, a new era of construction characterized by rapidly erected, lightweight steel structures rather than heavy masonry walls," explained Robert Fowler, senior engineer at the structural engineering firm of McNamara and Salvia. Clearly, these top engineers would reply in the definite affirmative. 2022 Scientific American, a Division of Springer Nature America, Inc. The image in question can be seen above on the cover of the disc. All the water above the hot aircraft bodies must have turned to steam. The dynamic forces are so large that the downward motion becomes unstoppable.". www.sciencedaily.com/releases/2011/09/110921074747.htm (accessed November 3, 2022). Views expressed here do not necessarily reflect those of ScienceDaily, its staff, its contributors, or its partners. ", "What sort of evidence do you have for the theory that you are putting forward? "In my theory, the hot fire weakened the supporting joint connection," Connor continued. 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.". "That's about 1 percent of the energy released by a small atomic bomb," he noted. 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 modelabout 24,000 gallons versus 23,000 gallons, according to Kausel. Kausel concluded that the "the largest share of the kinetic energy was converted to heat, material rupture and deformation of the ground below.". Click here to upload yours. As with all large buildings, the main structural engineering design criteria for the facility's 1,362-foot-tall south tower and 1,368-foot-tall north tower centered on two things: ensuring resistance to the gigantic gravity loads of the buildings themselves as well as to sideways or lateral forces caused by high winds and earthquakes, which can generate huge overturning forces at the bases. Yamaskai studied the models of more than 100 different building configurations before settling on twin towers that would soar more than a quarter-mile over a five-acre plaza, surrounded by three low-rise office buildings. Click here to upload yours. As 2021 marks the 20th anniversary, we looked back on how much has changed at the site of the World Trade Center. Just before the two New York skyscrapers collapsed on Sept. 11, 2001, powerful explosions within the building could be heard, leading many people to believe that overheated steel beams in the building were not the cause of the collapse. Questions? To see all content on The Sun, please use the Site Map. NUMBER OF PEOPLE AGE PEOPLE COMPOSITION ETHNICITY. Financial support for ScienceDaily comes from advertisements and referral programs, where indicated. ", "It would certainly be possible to look specifically for solidified droplets of aluminium and aluminium oxide in the walls of the neighbouring buildings. The objections came loud and clear from the other side of the Hudson: the PA was a bi-state agency, but all the projects benefits would go to New York. Seven years and eight months later, terrorists struck again. Such reactions are particularly powerful when rust or other catalysts are present, which can raise the temperature to more than 1500o C.", "The aluminium industry has reported more than 250 aluminium-water explosions since 1980. 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. "As the Trade Center was so much lighter in comparison to earlier designs, it was a watershed building in the history of skyscrapers," he added. In order to build the towers, engineers needed to dig down 70 feet to reach bedrock. In other words, I believe that these were the explosions that were heard by people in the vicinity and that have since given life to the conspiracy theories that explosives had been placed in the skyscrapers. It was in the morning New York time on September 11, 2001, when two Boeing 767 passenger planes flew into the World Trade Center's "Twin Towers" in Manhattan in New York. Publication date. 9:37am - Later, a third plane then hit the Pentagon in Washington DC. Kausel addressed the oft-asked question of why the towers did not tip over like a falling tree. Putin made 'catastrophic errors' in Ukraine war but tyrant hanging on to power, Gabby's family file suit against police & allege cop threatened mistress, Trespasser at Trump's Mar-a-Lago resort prompts huge Secret Service response, NXIVM member says cult 'will be back' & slams 'crazy' claims in Seduced doc, 2020 THE SUN, US, INC. ALL RIGHTS RESERVED | TERMS OF USE | PRIVACY | YOUR AD CHOICES | SITEMAP, Pictures of the collapse of the Twin Towers are some of the most iconic in history, The memorial to those killed sits in the shadow of the One World Trade Center, which replaced the Twin Towers, Incredible images show Americas heroes trying to save lives on September 11. It is the tallest building in the United States and Western Hemisphere. Other ideas floated included installing better fire-suppression systems, using the aqueous film-forming foams employed in aviation fires, and creating protected access ways for firefighters. The office floors, which each comprised a 35- to 60-foot clear span from the core to the exterior grid, were panelized structural members supported by open web joists with steel decks above them, he said. You can WhatsApp us on 07423 720 250. They lost: the courts gave the plan a green light. Existing skyscrapers should probably be retrofitted with some additional safety measures, but the professors say that it doesn't make sense economicallyand aestheticallyto protect them all physically from similar catastrophes. ", "WTC1 and WTC2 took huge amounts of aviation fuel, fragments of steel and, if my theory is correct, large quantities of molten aluminium when they collapsed. As LaGanga walked toward the north tower, smoke and dust began to fill the cerulean sky. Do you have a story for The Sun news desk? "A tree is solid, whereas building is mostly air or empty space; only about 10 percent is solid material. "Though the WTC towers stood over 1,360 feet above the street level, the structures' bases were actually set 70 feet into the ground, and one had a 100-foot-tall antenna atop it, so with 205-foot widths, they had a lot of [exterior] area facing the wind," the engineer stated. Outside of the basin, the temperature would have been much lower. ", "Many people in New York reported that they had heard explosions just before the buildings collapsed. ", "Could your theory be used to protect human life and material values if other skyscrapers are ever hit by large aircraft? Towers Falling [Rhodes, Jewell Parker] on Amazon.com. Skip recommended stories carousel and go to main content. ISBN-10. During the September 11 attacks, the Twin Towers were struck by two hijacked commercial aeroplanes. Email us at exclusive@the-sun.co.uk or call 02077824104. Negotiations eased New Jerseys qualms: the PA agreed to take over the bankrupt Hudson and Manhattan Railroad (now PATH), and build major container ports near Elizabeth. ", "To put it as succinctly as possible: because the federal government commission did not take sufficiently into account the fact that the aircraft brought 30 tonnes of aluminium into each of the two towers. Film taken of the buildings also showed explosions in the floor below the impacts. Email us at exclusive@the-sun.co.uk or call 02077824104. Fires. This article highlights the vulnerabilities of ultra-tall buildings to fire and points out steps that could be taken to lessen them. When New York City's giant World Trade Center towers plunged to earth following successive suicide terrorist attacks on September 11th, the world was confronted with one of most shockingand sickeningsights of modern times.

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