(CNN) At least nine people were killed in the 7.4 magnitude (M) earthquake that hit Taiwan on the 3rd of this month. According to an announcement by Taiwan’s Ministry of the Interior Fire Department (Fire and Disaster Management Agency), 770 buildings were also damaged.
The earthquake, the largest earthquake to occur in Taiwan in the past 25 years, caused buildings to shake violently in the capital, Taipei, located about 130 kilometers from the epicenter. However, thanks to a feat of modern engineering, Taipei 101, once the world‘s tallest skyscraper, remained intact.
In images of the earthquake, Taipei 101, which is approximately 508 meters high, appears to be shaking slightly, as the building’s structure is flexible to resist the earthquake’s powerful movements. The fact that the building sways clearly shows that Taipei 101’s most important defense against earthquakes is the reinforced concrete building material itself.
Combining the compressive strength of concrete and the tensile strength of steel, the material is flexible enough to allow the building to sway, yet stiff enough to withstand the strong winds and typhoons that frequently hit Taiwan. (The principle that buildings can withstand earthquake forces by moving with them, rather than resisting them, has shaped traditional architecture in earthquake-prone East Asian countries for centuries, from pagodas in Japan to palaces in China.) (I have supported you for a long time)
But at the top of the building, another innovation protects the 101-story skyscraper. This is a very large ball-like device called a “tuned mass damper” (TMD).
A 660-ton golden steel ball called the Tuned Mass Damper (TMD) is suspended from a thick cable inside Taipei 101/Richard Chung TW/Reuters/File via CNN Newsource
huge counterweight
Suspended by thick cables from the 92nd to 87th floors of the building, the golden steel ball can move about 1.5 meters in all directions, acting like a pendulum to counteract (or “dampen”) the shaking. It is said to perform a function.
“It’s essentially a very large counterweight,” Stefan Ahl, author of “Supertall: How the World‘s Tallest Buildings Are Reshaping Our Cities and Our Lives,” said in a phone interview. explained. “In the case of Taipei 101, it weighs 660 tons. It may seem extremely heavy, but compared to the weight of the entire building, it is only a small fraction.”
“When the building starts to shake,[the TMD]moves in the opposite direction. Taipei 101’s dampers are suspended. Therefore, when the building shakes, it moves in the opposite direction with a delay, absorbing the kinetic energy.” A hydraulic cylinder between the TMD and the building converts this energy into heat and disperses it, Al explained.
TMDs are used in skyscrapers around the world, including New York’s “extra-slim” skyscraper Steinway Tower and Dubai’s sail-shaped Burj Al Arab (which has 11 TMDs). ing. The device will play a vital role in protecting buildings from violent movements caused by “harmonic vibrations” that can cause structural failure during earthquakes, Al said.
He also likened this phenomenon to a tuning fork, saying, “[It’s]when the building resonates on its own and begins to vibrate.” “As (the building) shakes faster and faster, it could lead to it collapsing.”
TMDs, also called harmonic absorbers, are “tuned” to resonate at the same frequency as the building, but can disperse potentially devastating energy at slower or slower wavelengths.
The stability provided by TMD also reduces the discomfort and nausea that can occur to people inside when the building sways during strong winds.
What supports the structure
Taiwanese architectural firm C. Y. Taipei 101, designed by Lee & Partners, was the world‘s tallest building from 2004 to 2007, when it was surpassed by Dubai’s Burj Khalifa. The observation deck overlooking the groundbreaking TMD has now become a popular tourist spot, as the dampers sway during strong winds.
But this gigantic sphere is not the only design feature responsible for stabilizing Taipei 101, which stands near a major fault.
The building rests on a very deep foundation, 380 reinforced concrete and steel piles driven into the bedrock underground. Above this, the building’s core is connected via a massive steel outrigger truss structure to a series of “mega columns” placed around the perimeter.
Taipei 101 also complies with the strict earthquake-resistant building standards unique to an island located along the Pacific Ring of Fire, which surrounds the Pacific Ocean and causes large-scale earthquakes and volcanic activity from Indonesia to Chile.
But the design also involved extensive digital modeling and “shaking table” testing (testing models on equipment that reproduces the motion of an earthquake), which shows that buildings like Taipei 101 are more susceptible to earthquakes than others. , or how the epicenter responds to an earthquake closer to its epicenter, remains to some extent theoretical.
“Even with computer simulations, there are still physical things that you can’t really get from digital simulations,” Al said, adding, “Despite advances in technology, we still don’t do it in wind tunnels or on shaking tables. We are currently testing the design.”