Tower 1 and tower 2........North tower..........also is tower 1.......lockers 1 and 2......Hallowell.....where they used to put the computer at......to give u a bed.............Hallowell lockers.............2 random ones at the end...shorter than the rest......like tower 1 and 2........
Collapse of the World Trade Center
Coordinates: 40°42′41.12″N 74°00′44.00″W
The original World Trade Center in Lower Manhattan, New York City was destroyed during the terrorist attacks of September 11, 2001, after being struck by two hijacked commercial airliners. One World Trade Center (WTC 1) the "North Tower" was hit at 8:46 a.m. Eastern time and collapsed at 10:28 a.m. Two World Trade Center (WTC 2) the "South Tower" was hit at 9:02 a.m. and collapsed at 9:59 a.m. The resulting debris severely damaged or destroyed more than a dozen other adjacent and nearby structures, ultimately leading to the collapse of Seven World Trade Center at 5:21 p.m.
A total of 2,763 people were killed in the collapses, including 2,192 civilians, 343 firefighters, and 71 law enforcement officers as well as all the passengers and crew on the airplanes, which included 147 civilians and the ten hijackers.
In September 2005, the National Institute of Standards and Technology (NIST) published the results of its investigation into the collapse. The investigators did not find anything substandard in the design of the twin towers, noting that the severity of the attacks was beyond anything experienced in buildings in the past. They determined the fires to be the main cause of the collapses, finding that sagging floors pulled inward on the perimeter columns, causing them to bow and then to buckle. Once the upper section of the building began to move downwards, a total progressive collapse was unavoidable.
The cleanup of the World Trade Center site involved round-the-clock operations and cost hundreds of millions of dollars. Some surrounding structures that were not hit by the airplanes still sustained significant damage, requiring them to be torn down. Demolition of the surrounding damaged buildings continued even as new construction proceeded on the Twin Towers' replacement, the new One World Trade Center, which was opened in November 2014.[1]
Background
Upon completion, the Twin Towers were briefly the tallest buildings in the world, and at the time of the terrorist attacks they were still in the top five. One World Trade Center (WTC 1) the "North Tower" was, at 1,368 feet (417 m), six feet taller than Two World Trade Center (WTC 2) the "South Tower", which stood 1,362 ft (415 m) tall. At the time of the attacks only the then recently completed Petronas Towers in Kuala Lumpur, Malaysia and the Willis Tower (known then as the Sears Tower) in Chicago were taller.[2] Built with a novel design that maximized interior space, the towers had a high strength to weight ratio as they utilized a new "framed tube" design that required 40 percent less steel than more traditional steel framed skyscrapers.[3] In addition, atop WTC 1 stood a 362 ft (110 m) telecommunications antenna that was erected in 1978 bringing the total height of that tower to 1,730 ft (530 m), though as a nonstructural addition, the antenna was not officially counted.
Structural design
The towers were designed as framed tube structures, which provided tenants with open floor plans uninterrupted by columns or walls. The buildings were square and 207 ft (63 m) on each side but had chamfered 6 feet 11 inches (2.11 metres) corners making the exterior of each building roughly 210 ft (64 m) wide.[4] Numerous, closely spaced perimeter columns provided much of the strength to the structure, along with gravity load shared with the steel box columns of the core.[5] Above the tenth floor, there were 59 perimeter columns along each face of the building spaced 3 feet 4 inches (1.02 metres) on center.[5] While the towers were square, the interior cores were rectangular and were supported with 47 columns that ran the full height of each tower.[4] All of the elevators and stairwells were located in the core, leaving a large column-free space between it and the perimeter that was bridged by prefabricated floor trusses.[5] As the core was rectangular this created a long and short span distance to the perimeter columns.
The floors consisted of 4-inch-thick (10 cm) lightweight concrete slabs laid on a fluted steel deck.[4] A grid of lightweight bridging trusses and main trusses supported the floors with shear connections to the concrete slab for composite action.[5] The trusses had a span of 60 feet (18 m) in the long-span areas and 35 feet (11 m) in the short-span area. The trusses connected to the perimeter at alternate columns, and were therefore on 6.8-foot (2.1 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the perimeter side and a channel welded to interior box columns on the core side. The floors were connected to the perimeter spandrel plates with viscoelastic dampers, which helped reduce the amount of sway felt by building occupants.[5]
The towers also incorporated a "hat truss" or "outrigger truss" located between the 107th and 110th floors, which consisted of six trusses along the long axis of core and four along the short axis.[4] This truss system allowed optimized load redistribution of floor diaphragms between the perimeter and core, with improved performance between the different materials of flexible steel and rigid concrete allowing the moment frames to transfer sway into compression on the core, which also mostly supported the transmission tower. These trusses were installed in each building to su
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