The collapsed of the World Trade Center

On september 11 of 2001, three buildings of the compund of teh World Trade Center in New York city collapsed due to structural problems on the day of the terrorist attacks. The south tower fell down exactly at 9:59 am (local hour in NY), after being in flames during 56 minutes in fire caused the attack of the flight numer 175 of the United Airlines at 9:03 am.





By the other hand the north tower fell down at 10:28am after being in flames during 1 hour and 42 minutes in fire caused by the impact of the flight numer 11 of the American Airlines airplane at 8:46 am. The scientist said that the posible cause of the collpased of a third building at 5:20 pm was of the damage by the debris of the twin towers when this ones fell down, also with many series of fire.





Also is clear to know that many buldings near the place of the attack also suffered numerous damage, so they get on fire and they had to demolished. A technical investigation of the federal building and safety of the collapse of the Twin Towers and WTC 7 was conducted by the National Institute of Standards and Technology (NIST) of the Department of Commerce of the United States. The objectives of this investigation, which took into account the construction of the building, materials, and technical conditions that contributed to the collapse of the incidente of that day were investigated, of this investigation there were some bases established like:

• Improve the standars that which the buildings are design, used, manteined and constructed.
• Improve the tools and signs for the construction industry and for those responsible for the security.
• Revisions of the regulations of fire in buildings, standards and practices.
• Improvements in public safety.

Also the report saids that the fire protection of the infrastructure of the Twin Towers were released with the initial impact of the planes, and if this would not happened, the towers of New York would still standed in the city.



The fire weakened the trusses holding the floors, and made that the floors were fell down. When the floors get down, that provokes that the columns were inclinated and also fell down. With the weight of the principal columns, the interior columns cant support it and thats why both of the towers get down.

Sept. 11, when the world trembled

3 years ago, the United States of America suffered and leaves the major terrorist attack on its territory and on it history. The attack was presented by a group of Islamic fanatics that on 11 of September of 2001 attacked the financial heart of the country in New York, the World Trade Center and also the house of defense, the Pentagon in Virginia.

The fact of this terrorist act consisted by this way: the islamics were divided into 4 groups of kidnappers, each of the groups has with them a pilot that was in charged of drive an airplane once already the tripulation was reduced in the machine. The first airplane were of American Airlines, that was the flight 11 and the other were de flight 175 but from United Airlines. Both of the airplanes were starryed against the twin tower in New York, in the World Trade Center of this city, each of the airplane crash against each of the two towers, this caused the fall of the twin towers after two hours approximately.

By other side, the third airplane kidnapped was the American Airlines flight 77 that crashed in the corner of the Pentagon, in Virginia. And the airplane number four, that was the United Airlines flight number 93, cant crash any target that was planned, because the crew made up of the passengers were able to prevent and control it and that genre that this plane has been stopped in an open field in Shanksville, Pennsylvania.

Taking about the deads, is clear to know that apart from the 19 kidnappers, there were about 2973 people confirmed dead and about 30 still missed as the consequences of these attacks. This terrorist attack was characterized by the deads, the consequences and inclusing the use of airplanes as fact of weapons creating a situation and a moment of fear all around the planet and making the start of the war on terrorism. This attacks were called by the UN Security Council as a "Heinous Terrorist Attacks".