What if world trade center

The building is 1, feet in height, which was by design to have some historical significance. The height pays tribute to the United States being born in The old Twin Towers were 1, feet.

One World Trade Center is the seventh-tallest building in the world. The building has stories, much of which is used for office space. As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell.

The floor below with its 1, t design capacity could not support the roughly 45, t of ten floors or more above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of km per hour. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself.

Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure.

Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a , t structure has too much inertia to fall in any direction other than nearly straight down. The World Trade Center was not defectively designed. No designer of the WTC anticipated, nor should have anticipated, a 90, L Molotov cocktail on one of the building floors.

Skyscrapers are designed to support themselves for three hours in a fire even if the sprinkler system fails to operate. This time should be long enough to evacuate the occupants. No normal office fires would fill 4, square meters of floor space in the seconds in which the WTC fire developed.

Usually, the fire would take up to an hour to spread so uniformly across the width and breadth of the building. This was a very large and rapidly progressing fire very high heat but not unusually high temperature. After all, 1,, t of rubble will require 20, to 30, truckloads to haul away the material. The asbestos fire insulation makes the task hazardous for those working nearby.

Separation of the stone and concrete is a common matter for modern steel shredders. The land-filling of , t of concrete and stone rubble is more problematic. There will undoubtedly be a number of changes in the building codes as a result of the WTC catastrophe. For example, emergency communication systems need to be upgraded to speed up the notice for evacuation and the safest paths of egress. Emergency illumination systems, separate from the normal building lighting, are already on the drawing boards as a result of lessons learned from the WTC bombing in There will certainly be better fire protection of structural members.

Protection from smoke inhalation, energy-absorbing materials, and redundant means of egress will all be considered. A basic engineering assessment of the design of the World Trade Center dispels many of the myths about its collapse. First, the perimeter tube design of the towers protected them from failing upon impact. The outer columns were engineered to stiffen the towers in heavy wind, and they protected the inner core, which held the gravity load. Removal of some of the outer columns alone could not bring the building down.

Furthermore, because of the stiffness of the perimeter design, it was impossible for the aircraft impact to topple the building. However, the building was not able to withstand the intense heat of the jet fuel fire. While it was impossible for the fuel-rich, diffuse-flame fire to burn at a temperature high enough to melt the steel, its quick ignition and intense heat caused the steel to lose at least half its strength and to deform, causing buckling or crippling.

This weakening and deformation caused a few floors to fall, while the weight of the stories above them crushed the floors below, initiating a domino collapse. It would be impractical to design buildings to withstand the fuel load induced by a burning commercial airliner. Instead of saving the building, engineers and officials should focus on saving the lives of those inside by designing better safety and evacuation systems.

As scientists and engineers, we must not succumb to speculative thinking when a tragedy such as this occurs. Quantitative reasoning can help sort fact from fiction, and can help us learn from this unfortunate disaster. As Lord Kelvin said,. We will move forward from the WTC tragedy and we will engineer better and safer buildings in the future based, in part, on the lessons learned at the WTC.

The reason the WTC collapse stirs our emotions so deeply is because it was an intentional attack on innocent people. It is easier to accept natural or unintentional tragedies; it is the intentional loss of life that makes us fear that some people have lost their humanity. Feature: Special Report. Most have provided qualitative explanations; however, simple quantitative analyses show that some common conclusions are incorrect; for example, the steel could not melt in these flames and there was more structural damage than merely softening of the steel at elevated temperatures.

Activities included: Interviews with 1, surviving occupants of the WTC buildings and emergency responders. Extensive reviews of design, construction, maintenance and inspection documents for the buildings Examination of hundreds of structural steel components from WTC buildings Gathering and analyzing thousands of pieces of video, photographic, and audio evidence from professional sources and the public NIST's World Trade Center Investigations.

Featured Content About the Investigation. Investigation Meetings. News Archive. Photos, Videos and Simulations. Publications and Reports. Disaster and Failure Studies Repository. The Reports. Read the blog post from Shyam Sunder. The Legacy. As chance would have it. The kickoff meeting On Nov. On Tuesday, Sept. I had just. I consider myself lucky to have been able to perform contract engineering research and consulting for my entire career. The work environment has been somewhere.