7 World Trade Center#Original building .281983.E2.80.932001.29

The former 7 World Trade Center ( abbreviated: 7 WTC, also: WTC 7 or Salomon Brothers Building; German World Trade Center - building 7, to distinguish even the original 7 World Trade Center called ) was an office building in Manhattan (New York City). It collapsed after persistent fires in the buildings which had been caused by falling to the terrorist attacks on 11 September 2001 wreckage of the building WTC 1. From 2002 to 2006 was built on the property, the new 7 World Trade Center.

Construction

The old WTC 7 was built as a building in the complex of the World Trade Center 1984-1987 and opened in March 1987 with an office area of 174,000 m². The design was by architects Emery Roth & Sons. The building stood to the north of Vesey Street outside the actual World Trade Center quadrangle. It had 47 floors and a height of 174 meters, was covered with a reddish granite facade and connected via a pedestrian bridge to the main complex. It bridged an underground electric station and therefore had a special design around an atrium that few, associated with horizontal steel beams supporting pillars wore large areas of the building and thus extremely heavy weights.

Tenant 2001

The administration of the World Trade Center leased office space among other things, financial and insurance companies and government institutions. Thus, the banking companies Salomon Smith Barney, American Express Bank International, Standard Chartered Bank and Provident Financial Management, and the insurance company ITT Hartford Insurance Group, First State Management Group, Inc., Federal Home Loan Bank and the National Association of Insurance Commissioners ( NAIC) were (NAIC Securities ) housed in the building.

In addition, in WTC7, the U.S. Securities and Exchange Commission and the Equal Employment Opportunity Commission ( EEOC ) were housed.

Collapse

The building was hit in the collapse of WTC 1 on September 11, 2001 by the debris and severely damaged. It came on several floors and sides of the building to persistent fires that were fueled by materials in the building. Attempts to delete the fires were abandoned about 15:30 local time clock and deducted the firefighters involved in order to expose them to any danger. At the same time, the area was around the building evacuated over large areas so that no people were injured in the collapse.

The building collapsed at 17:20 clock in a progressive collapse in on itself. The first is bulging east side of the building drew the west side diagonally downward. The visible at different video recordings outer collapse began with the collapse of the first eastern, about ten seconds later the Western penthouse on the roof, which was followed by a medium- slight bend in the horizontal roof and the rapid collapse of the remaining whole building.

Due to the collapse of some adjacent buildings were damaged, including the west standing Barclay - Vesey Building, and particularly the north neighboring building 30 West Broadway. It was demolished in May 2009 to November 2009. A similarly large bridge subsequently was completed in August 2012.

Investigation reports

FEMA investigated the collapse of building a temporary basis, based on known data and building of video and photo material. In its report of 2003, she participated in a collapse of structural elements in the building, which preceded the externally visible total collapse and began in lower floors of the eastern part of the building. Weight shifts would then transfer support and / or buttress buckle in the middle part and let fail. This failure had spread to the western part of the building. From what had been failing support element on which floor the total collapse initiated, can be established only after future detailed individual studies. The report cited the collapse sequence:

The final phase took about seven seconds on the north side of the building after video footage of it. The total collapse time of up to 44 seconds disproves a widespread conspiracy theory that the collapse had taken place almost in the rate of free fall, and thus must have been caused by a controlled demolition.

The U.S. Government National Institute of Standards and Technology ( NIST) published in 2002 a preliminary report on the WTC collapses on a tight part on WTC 7 The announced final report for this building has been postponed several times. This was speculation and conspiracy theories for food September 11, 2001. 2006 declared the head of the investigation Shyam Sunder, the final report was due to lack of staff, budget shortages and difficulties to verify the initial hypotheses about the collapse delayed. In 2007 he reported on progress of the investigation thanks to improved technology and knowledge to the first studied collapse of WTC 1 and 2

On 21 August 2008 NIST announced presented the final report. This construction plans, witness statements and video recordings as well as an elaborate computer reconstruction and simulation were evaluated. After falling debris of the Twin Towers sparked persistent fires inside the building, which were favored by a failure of a built-in sprinkler system and their herd of firefighters were not accessible. The initial guess, diesel fuel from tanks in the basement have contributed to the heat and so the collapse, not hardened. The fire caused by the thermal expansion of the vertical and horizontal steel beams initially led to the sacking of false ceilings and buckling of some buttress. Especially between the 10th and 13th floor of the horizontal ceiling beam of the supporting pillars number 79 jumped off, until he came to stand freely on nine floors, and finally buckled by overload. This led to the last "progressive collapse" of the building.

The report identifies thermal expansion as new, previously unknown cause of a structural collapse of steel frame structures. It excludes that even the cascading rubble of the Twin Towers, the building structurally so badly damaged that it had to collapse. Also, a blast of the building is excluded, since all indications are missing this: the required amount of explosives could not be unobserved installed in the building and there properly. Similarly, the investigators found no testimony for a - necessarily serious - explosion.

A documentary by the BBC, the ZDF broadcast 7 September 2008, presented this collapse causes. Specialists for building demolitions pointed out that there was no evidence for the theory of a demolition of the building, because neither cable nor residues detonators or explosives residues were found. An unobserved preparation of such demolition is hardly possible. Thus they rejected the conspiracy theory that an intentional demolition traces of a government involvement in the terrorist attacks of September 11 was intended to blur.