What keeps Taipei 101 safe from wobbling?
Taipei 101 which was formerly known as the Taipei World Financial center is a skyscraper situated in Xinyi District, Taipei, Taiwan. The building architecturally serves as a symbol of the evolution of technology as well as highlights Asian tradition .The Taipei 101 tower comprises 101 floors above ground and 5 floors underground. As good as it looks, it took lot of engineering to make it a reality. The skyscraper has to survived the brunt of heavy winds, thyphoons and earthquakes. There is lot of engineering which one cannot see from the outside but on the inside all is revealed. Wind loads is a very crtitical factor in any skyscraper construction . Heavy winds can cause can cause the top of skyscrapers to move more than a meter. This motion can be in the form of swaying or twisting, and can cause the upper floors of such buildings to move. This is not especially good in case of concrete structures as there is a chance of failure due to excessive movement. So how have engineers tried to keep the movements within limits?
Tuned Mass Damper
A tuned mass damper, also known as a harmonic absorber, is a device mounted in structures to reduce the amplitude of mechanical vibrations. Their application can prevent discomfort, damage, or outright structural failure. They are frequently used in power transmission, automobiles, and buildings.
Taipei 101 consists of a sphere, the largest damper sphere in the world, consists of 41 circular steel plates of varying diameters, each 125 mm thick, welded together to form a 5.5 m diameter sphere. Two additional tuned mass dampers, each weighing 6 tonnes, are installed at the tip of the spire which help prevent damage to the structure due to strong wind loads. The 660- metric ton steel sphere is suspended by eight cables in the upper stories of the tower, and is visible between the 88th and 92nd floors. When the building bends in a certain direction the TMD sphere moves in an opposite direction thus limiting the movement within limits.
On 8 August 2015, strong winds from Typhoon Soudelor swayed the main damper by a record 100 cm. It proved its effectiveness then and in many other cases. But the constrcution of TMD was not cheap. It cost $4 million to build.