High-profile storm-proof architecture
The MB Building Kit System’s profile technology also demonstrates its credentials day in, day out in another world-renowned structure that needs to withstand specific weather conditions. It helps protect the Shanghai Tower against vibrations. The architectural concept behind the world’s second highest building was the creation of a vertical “city within a city” comprising nine sections. A single section is made up of 12 to 15 floors. A dazzling range of boutiques, shops, gardens, conference rooms, offices and hotels awaits visitors, spread over a floor area of 380000 square metres. 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 kilometres per hour.
The most visually striking aspect of the building is its spiral shape, but that isn’t just a bit of fun – it’s highly effective in a number of ways. The final shape of the Shanghai Tower is based on an extensive series of wind tunnel tests. By factoring the test results into their design, the architects were able to achieve a 24 percent lower effective wind loading. 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.
The Shanghai Tower owes its excellent stability to innovative technology.
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. A 1000 metric ton weight is located between the 125th and 126th floors. This 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. The principle of the eddy current brake means the Shanghai Tower is largely resistant to external vibrations.
Building this solution with steel supports wasn’t an option, as these would have been permanently subject to attraction. Unlike iron, aluminium is paramagnetic. The holding force of the profiles ensures the copper plates can withstand the enormous force of attraction from the magnets long term. In fact, the magnets are powerful enough to lift an aircraft weighing 300 metric tons. However, the robust aluminium profiles stop the magnets and copper plates from coming into contact and thus maintain the braking effect. Chinese and Japanese profiles were also tested beforehand, but the end result was clear: “In our comparative test, item offered the best quality,” underlines Qian Feng, deputy architect in chief of the Shanghai Tower.
Steel not an option
The low weight of the profiles proved to be another crucial advantage, as they had to be lifted to a height of 600 metres by a tower crane and then carried seven floors down by hand. 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 auxiliary equipment such as cranes or lifting platforms was required when fixing the profiles in place. Nevertheless, the aluminium design boasts the same strength as 304 stainless steel and even Q235A steel.