'They burned wrong and fell wrong': debunking conspiracy theories around the September 11 attacks

Countless conspiracy theories have emerged since 11/22, the day terrorists hijacked planes and attacked the World Trade Center in New York. That was XNUMX years ago, but conspiracy theories are still alive and well, writes GreekReporter.

The collapse of the World Trade Center became the subject of intense public attention after planes hijacked by terrorists crashed into the Twin Towers. Both towers collapsed within two hours of the collision, prompting a number of investigations and spawning many conspiracy theories.

Conspiracy theories

In many conspiracy theories of the disaster, it is assumed that the collapse of skyscrapers occurred as a result of the explosion of supporting structures (aircraft could not do this, which means, as conspiracy theorists suggest, the US government did). This conclusion was made on the basis of the similarity of shots of the fall of skyscrapers and the demolition of similar buildings with the help of explosions. Many shots of the twin towers falling, the researchers say, clearly show explosions inside the towers, characteristic of a controlled demolition of buildings.

Some dry facts

Construction of the north and south towers of the World Trade Center began in the 1960s. They were built from steel and concrete using a design that was innovative at the time. Since then, most high-rise buildings have had a similar design.

The investigation into the events of September 11, 2001 was conducted by the US Federal Emergency Management Agency (FEMA) and National Institute of Standards and Technology. The FEMA report was published in 2002. It was followed by a three-year investigation by the National Institute of Standards and Technology (NIST), funded by the US federal government, published in 2005.

Some conspiracy theorists have seized on the fact that the NIST investigation was funded by the federal government, suggesting that the government itself caused the collapse of the Twin Towers or knew it would happen but deliberately failed to act.

On the subject: The 9/11 attacks are overgrown with conspiracy theories: where they come from and why people believe in speculation

Although both reports have been criticized (and the investigations themselves were not flawless), their explanation of the reasons for the collapse of buildings is generally accepted. In their opinion, the cause of the collapse was not a direct collision with the aircraft or the use of explosives, but a fire that broke out inside the buildings after the collision.

So let's debunk some of the most common claims made by conspiracy theorists.

Why didn't the towers collapse immediately?

Some have questioned why the buildings did not “tip” on their sides after the side impact of the plane. But the answer becomes clear when we look at the details.

Airplanes are made from lightweight materials such as aluminum. If you compare the mass of an airplane with the mass of a skyscraper with a height of more than four hundred meters, built of steel and concrete, it becomes clear that the building will not tip over. The mass of the towers was more than a thousand times the mass of the aircraft and were designed to withstand sustained wind loads of more than thirty times the mass of the aircraft.

However, as a result of the plane crash, the fire retardant material that covered the steel columns and steel floor trusses (under the concrete slab) was knocked out of the towers. The lack of fire protection left the steel unprotected.

Therefore, the impact damaged the load-bearing steel columns. When several columns are damaged, the load they carry is transferred to other columns. That is why both towers withstood the initial blows and did not collapse immediately.

Fire or conspiracy?

One of the most common theories surrounding the events of September 11 is that the bomb or explosives must have been detonated somewhere inside the buildings. These theories arose from video footage that showed the towers rapidly collapsing (“collapsing”) some time after the impact, in what appears to be a controlled demolition. However, it is possible that they collapsed in this way without explosives.

The cause of this was a fire, which is believed to have arisen as a result of the combustion of aviation fuel remaining in the aircraft. According to the FEMA report, the fire in the buildings caused the floors to expand thermally horizontally and outward, pushing against the rigid steel columns, which buckled outward but resisted further expansion of the floors.

As the columns resisted, the concrete floors had no room to expand. This caused stress to build up in the sagging floors until the frame and floor joints gave way and collapsed. As a result of the destruction of the floors, the columns were sharply pulled inward, which led to their fracture and the collapse of the floors. The collapsed floors then fell onto other floors below, causing progressive collapse.

This explanation, documented in official records, is widely accepted by experts as the cause of the collapse of the Twin Towers. The South Tower is believed to have collapsed earlier because it suffered more damage from the initial aircraft impact, which also dislodged more fire-retardant material.

The collapse of the North Tower set at least ten floors on fire at the nearby World Trade Center 7, which also collapsed about seven hours later. Although there are different theories as to how the collapse of this building began, investigators unanimously believe that fire was the primary cause of the destruction.

Both official reports made a number of fire safety recommendations for other high-rise buildings, including improving evacuation and emergency response systems. In 2007, the US National Institute of Standards and Technology also published guidance with recommendations for reducing the risk of progressive collapse.

The problem of instability of high-rise structures has not yet been resolved

Before 11/XNUMX, progressive collapse was not much studied by engineers. The disaster highlighted the importance of taking a “global view” of building fire safety rather than focusing on individual elements.

Since then, building codes have been amended to improve fire performance of buildings as well as evacuation capabilities (e.g., adding requirements for stairwells).

At the same time, the collapse of the Twin Towers demonstrated the real danger of fire in high-rise buildings. In the decades since the World Trade Center was designed, buildings have become taller and more complex as society demands sustainable, cost-effective housing in major cities.

About 86 of the world's 100 tallest buildings were built after 11/XNUMX. This has coincided with a significant increase in the number of building façade fires worldwide, which has increased sevenfold over the past three decades.

Part of this growth can be attributed to the widespread use of flammable cladding. It is touted as an innovative, cost-effective and environmentally friendly material, but from a fire safety perspective it has significant disadvantages, as evidenced by the Grenfell disaster in 2017.

The Grenfell fire (and similar cladding fires) is proof that fire safety in high-rise buildings is still a problem. As structures become taller and more complex through the use of new innovative designs and materials, answering fire safety questions will become increasingly difficult. The events of 11/XNUMX may have been difficult to foresee, but the fires that led to the collapse of the towers could have been better prepared for.