What was the width of the twin towers

What shape are twin towers? How thick was the steel in the Twin Towers? Who owned Windows on the World? What was found in the rubble of 9 11? What time was the first tower hit? How long did the World Trade Center smoke? How far did the smoke from travel? When did the first plane crash on ? What is the highest floor someone survived 9 11? 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.

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.

Eduardo Kausel proposed an alternative failure explanation that he acknowledged was independently developed by Zdenek Bazant, a professor at Northwestern University. 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. He also performed some computer simulations that indicate the building material fell almost unrestricted at nearly the speed of free-falling objects.

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. Kausel addressed the oft-asked question of why the towers did not tip over like a falling tree.

Since there is no solid stump underneath to force it to the side, the building cannot tip over. It could only collapse upon itself. Though the recent "disaster couldn't be envisioned as a design scenario in the s, it means we have to change the way we design and construct tall buildings in the future," Buyukozturk said.

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.

To do so successfully means boosting a building's structural redundancythe provision of additional means to assist system function. 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.

One audience attendee, a West Coast-based structural engineer who did not give his name, created a provocative moment when he claimed that it would cost about 10 percent more than the original building cost to install floor joint reinforcements for greater redundancy. Though it's horrible to contemplate," he continued, "a human life is valued for insurance purposes at about a million dollars apiece, so this helps put the extra investment into perspective. After all, the World Trade Center was retrofitted with 10, viscoelastic dampers to reduce its swaying, so safety improvements can't be ignored.

Building clients have to become more demanding, even if the probabilities of a repeat disaster are very slim 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".

He also suggested that more effort should be expended to create "alternative escape routes, so evacuees aren't faced with a wall of smoke. If two stairwells are close together," he noted, "one explosion could block them both. There was also mention of the need to harden stairwells and egress pathways, and perhaps develop "deployable evacuation systems" for building occupants. Beyond robotic stairway evacuation devices, deployable systems might include escape tubes deployed out windows, exterior people-lowering machines, flying platforms or even parachutes.

Their response indicated that a concrete structure would have probably lasted for a couple of more hours than did the steel World Trade Center towers. Robert McNamara stated that many of the more recent superskyscrapers were constructed of reinforced concrete mainly because of the high cost of steel in Asia. He also mentioned that the Petronas Towers contain "safe refuge floors" to allow building occupants to reach fresh air during fires. McNamara said that this concept was now somewhat discredited, as similar refuges in the WTC would not have ultimately saved anyone.

A lively discussion then ensued about whether the terrorist pilots knew where to hit the buildings for maximum effect. McNamara opined that the position of impact seems significant. The earlier [truck bomb] attack showed that the explosion at bottom had little effect and that it's much easier to collapse a building from the top than the bottom.

If they had hit the very top of the building, the fire damage wouldn't have had such a catastrophic effect. At the bottom, the columns are much heavier and stronger and so they would have taken a much larger load. Clearly, these top engineers would reply in the definite affirmative. Inevitably, they said, new tall towers will rise. Already a subscriber?

Sign in. The World Trade Center was conceived in early by the Association of Lower Manhattan Development, aiming to revitalize the seedy area occupied primarily by electronic stores. The chairman of Chase Manhattan Bank, David Rockefeller, founder of the development association, and his brother, New York governor Nelson Rockefeller, pushed for carrying out the project, insisting it would benefit the entire city. Under this complex, access to the train station to Jersey City, and three stations were subway lines.

These are words of Minoru Yamasaki who with the design of the Twin Towers posed to the Big Apple and all the citizens of New York coexistence on arrogance, represented by the duality of the two towers.

These became the new image of the city, the gateway transmitting a message of brotherhood for which had to be some time before it came to be captured by the popular intuition. Most are surface was occupied by offices of 28 different countries, but also had exhibition halls, auditoriums, restaurants, a hotel with rooms, equipment rooms and service.

To plant were 41 and 74 Express lifts, with lobbies at those levels, connecting with a second network of elevators that let the traveler in other plants, thereby avoiding some stops and making the climb in less time. Also there was a direct lift from the first floor to the , without any stop. It was occupied by bank branches, offices telecommunications, Sun Microsystems technology , units of the New York Stock Exchange on floors 28 and 30, Siemens Telecommunications, insurance companies and investment, publishing, Department of Finance and Treasury of New York and veranda on the and plant.

From this apartment , where a restaurant offering sweeping views of the city, you could access the terrace which was in the th floor via escalators. It was one of the few places open and accessible to the public. There were seven underground levels including amenities, parking with spaces, shops, a railway station and several subway. The entire perimeter surrounding the central core was played with dried modules.

The intermediate space between the central core and the perimeter fence, no columns was vertically segmented by the slabs of plant consisting of thin concrete slabs 10 cm thick on a sheet metal decking strapping steel, which in turn is supported in a slender trusses linking the core to the perimeter at alternate columns framing.