On September 11, 2001, Americas World Trade Centers was attacked by a faceless enemy, and the people of America stood in shock and mourning. On lookers watched in horror and disbelief, struggling to comprehend what was happening. But at the time there was no answer. All over the country people turned on their televisions and watched as another Bowing 767 crashed into the second tower. The question that’s in the back of my head is why did the building collapse after the planes crashed into the towers? If the engineers and architects had designed the Twin Towers differently could a tragedy like this have been avoided?
The World Trade Center was built around columns that were closely spaced around the perimeter of the towers. Engineers used light weight steel trusses between the elevator and the columns of each floor. The trusses were designed to support the concrete floor and tie together the perimeter to the core of the building. After the planes initial impact nobody thought the impossible was going to happen. Visually you could tell the crash destroyed many floors and took off a significant number of columns. After the planes crashed the jet fuel enflamed the building with temperatures the building could not withstand. The sprinkler systems in buildings such as these are designed to put out office fires, not explosions caused by a plane crash. Eventually, the fire weakened the structure of the skyscraper, and combined with the damage of the impact, caused the floors to collapse one floor after another leaving behind a pile of steel and smoke.
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More than 2,200 people died in the 9-11 tragedy because they were trapped above the crashed floors. The stairwells were filled with sheetrock and burning materials. This rubble completely blocked the stairwells and prevented evacuation. This wallboard system was very well engineered for a fire, but not a fire that was caused by the impact of a 767. The initial impact was great enough to collapse this system which would have stopped fire and smoke from spreading to the stairwells. Once theses walls where breached, the victims had no chance. There is also the possibility the breached walls allowed the burning fuel to reach the stairwells.
What’s the answer to this problem? It’s as simple as building stronger walls made of either new steel or maybe even a combination of concrete and steel. Another wise decision would be to make wider stairwells for a better flow and have them located on both sides of the each building. This would allow you to access more than one stairwell if there is a fire in between you and the exit. In the case of the Twin Towers stairwells access was designed in the middle of the buildings. In 1945 an Air Force bomber crashed into the 79th floor of the Empire state building, only 14 people died and it stood standing. Its thick masonry walls over came the very hot fire.
In the last 20 years computers have taken over the designing of buildings and nobody really changed the premises for 100 story skyscrapers. In the future when a building is being designed they should make teams that would include structural engineers, architects, fire marshals, and fire engineers. This will allow them to make decisions like, “we can’t have a fire exit there”. After September 11, 2001 the world has changed. In every decision we make we should expect the unexpected. I think this event has opened up Americans eyes and allowed us to realize that we have to be more cautious. We should wonder why there are 5 Taliban’s all learning how to fly a plane. Unfortunately, in this case the twin towers were pushed beyond their limits and we can only try to prevent another September 11. I’m not saying we should hold engineers and architects responsible for 9/11 but just don’t make the same mistake twice. Don’t let there be another situation were 2,200 people die because we didn’t expect the unexpected.
October 6 th was certainly a night to remember. I was on my way home from a friend s house. I hadn t traveled far when I came across my friend s truck on the side of the road. I parked my truck nest to his and got out to help. About thirty minute s later fire trucks and police cars began driving by, lights and sirens filling the night. Where they were headed no one knew, since my friend was a ...