Published On: February 27th, 2017 ¦ Categories: Industries, News ¦ 3.3 min read ¦ Views: 6516 ¦

Shanghai Tower: The secret to its stability

The Shanghai Tower is the second-tallest building in the world, after the Burj Khalifa (Dubai).

It took almost seven years to build the gigantic skyscraper, at an estimated cost of between USD 1.5 and 2.4 billion. Located in the heart of Pudong, Shanghai’s financial and economic centre, the Shanghai Tower is in good company, surrounded as it is by the Jim Mao Tower and the Shanghai World Financial Center, known affectionately to the locals as the “bottle opener” due to its unusual shape. However, don’t be deceived by the dense concentration of skyscrapers – the natural conditions in Shanghai pose significant challenges for engineers. Earthquakes and storms cause strong vibrations and compensating for those calls for great skill. But that is precisely where the profiles in our MB Building Kit System come in.

Think big!

It isn’t just the height of the Shanghai Tower that makes a lasting impression. The architectural concept behind the building was the creation of a vertical “city within a city” comprising nine sections, each made up of 12 to 15 floors. A dazzling range of boutiques, shops, gardens, conference and office rooms, and hotels awaits visitors, spread over a floor area of 380,000 m². A total of 128 floors are interconnected by 149 lifts, three of which are the fastest in the world, notching up a travel speed of 65 km/h.

The most visually striking aspect of the building is its spiral shape, but that isn’t just a bit of fun, it is highly effective in a number of ways. The final shape of the Shanghai Tower is based on a series of wind tunnel tests. By factoring the test results into their design, the architects were able to lower effective wind loading by 24 percent. What’s more, this special, stripped-down architecture helped to reduce costs by USD 58 million. But that’s not all – thanks to the spiral design, the building collects rainwater to be used in heating and air conditioning systems.

Reaching for the skies with aluminium

However, it isn’t just the shape of the building that helps it withstand the tough conditions in Shanghai – there is also a 1000 metric ton weight located between the 125th and 126th floors. The weight is suspended from 12 steel cables so that it can oscillate when subjected to vibrations. Underneath the weight are plates of pure copper that are fastened to the reinforced concrete floor using item profiles. Huge permanent magnets on the weight help to induce Eddy currents in the copper plates, thereby generating a magnetic field that works in the opposite direction to the weight to generate a contactless braking effect – even during a power failure. Thanks to the principle of the Eddy current brake, the Shanghai Tower is largely resistant to external vibrations.

Building this solution with steel supports was not an option, because these would have been permanently subject to attraction. Unlike iron, aluminium is paramagnetic. The holding force of the profiles ensures the plates can withstand the enormous force of attraction from the magnets for the long term. In fact, the magnets are powerful enough to lift a 300-metric-ton aircraft. However, the robust aluminium profiles stop the magnets and copper plates from coming into contact and thus maintain the braking effect.

The low weight of the profiles also proved to be a crucial advantage, as they had to be lifted to a height of 600 metres by a tower crane then carried by hand down seven floors. Had steel supports been used, it would have taken more than three times as many construction workers to move them into position. What’s more, no additional tools such as cranes or lifting platforms were required when fixing the profiles in place. Nevertheless, the aluminium design boasts the same strength as 304 stainless steel and even Q235A steel.

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