Industry№ 3 December 2017

The construction of high-rise buildings is often viewed as a symbol of ambition. Yet, within an ever-expanding urban landscape, such buildings offer a practical solution for saving space. It was for this purpose that the very first skyscrapers were built in America a century ago, and today we are following the same trend. Although technological progress has sped up substantially in this area, one main characteristic remains the same – building skyscrapers requires a lot of metal.

By today’s standards, the first skyscraper was only modestly high – with just 10 floors, the Home Insurance Building in Chicago reached only 42m. However, in 1885 it was a sensation. Its architect, William Jenny, installed a bearing steel frame, which reduced the load on the walls.

In 1913, the Woolworth Building (241m, 57 floors) was erected in New York. It was built to steal the title of the tallest building in the world from another one of New York’s skyscrapers, called the MetLife Tower (213m, 50 floors). Thus, the race to build ever-taller buildings began. “In their symbolism, skyscrapers could be compared to palaces and churches around the world. They share a common objective – to highlight the importance of the customer and to push the scientific, technological and even cultural development of society forward,” believes Vladimir Neustruev, a building structures consultant.

Skyscraper Fashion

For a long time, Russia’s tallest buildings were Saints Peter and Paul Cathedral and Saint Isaac’s Cathedral in Saint Petersburg (122.5m and 101.5m respectively). Skyscrapers came into fashion only in the 20th century under the name ‘tucheresy’, meaning ‘cloud cutters’. Moscow led the trend. One by one, the city began to build multi-storey buildings, the most famous of which was the Nirnsee House. With its 11 floors (40m), it was similar to the Chicago Home Insurance Building.

During the Soviet regime, in the 1930s, two important Moscow buildings – the Cathedral of Christ the Saviour and the Sukharev Tower – were demolished. “Soviet people will create more majestic and memorable examples of architectural creativity,” said Stalin, adding the USSR to the race for the tallest building in the world. However, World War II, which reached the country in 1941, interrupted architectural plans, and the construction of the Palace of Soviets was stopped. Later, the Seven Sisters, a group of seven skyscrapers in Moscow designed in the Stalinist style, joined the competition. One of them, the main building of the Moscow State University (239m, 34 floors), held the title of the tallest building in Europe for 37 years; but this is only if one excludes the Television Tower (Ostankino Tower), which from 1967 holds the record in Europe at 540.1m high (compare to Berlin Television Tower – 368m).

In the 21st century, Moscow skyscrapers once again began to compete with each other for the title of the main skyscraper in Europe. The first was the Triumph Palace (264.5m, 57 floors) in 2005, followed by the Moscow International Business Centre, known as the Moscow City. At 374m high (97 floors), one of its skyscrapers – the eastern tower called the Federation Tower – remains the tallest building in Europe. However, it is expected that the St. Petersburg Lakhta Centre will overtake this record in 2018.

The Television Tower (Ostankino Tower), which from 1967 holds the record in Europe at 540.1m high

The Importance of the Filling

When it comes to building skyscrapers, there is no such thing as one size fits all – each project is unique in its own right. The world’s tallest twisted high-rise building, with a twist of 90 degrees, is the Infinity Tower in Dubai (307m, 73 floors). Although at a lesser height – 246m, 55 floors – The Evolution Tower in Moscow has an even greater twist of 156 degrees. It is designed with a vertical structural RC frame supported by a central monolithic reinforced core. It also has one of the most innovative cold-bent glazings in the world, says Petr Zhuk, Professor of the Department of Architectural Materials at the Moscow Architectural Institute.

However, while the structural elements of the Evolution Tower are made of a concrete-containing mixture, its neighbour – the Eurasia Tower (309 m, 71 floors) – uses a frame made entirely of steel. This is a very common solution. In the United States of America, for example, 65% of high-rise buildings are built with steel-only frames. In Russia, however, the monolithic concrete core is more popular. In this respect, the Eurasia Tower is a pioneer of new ideas, although its predecessors, like the Seven Sisters, used the same formula.

But whatever the design, there is always one major prerequisite – every skyscraper needs to be built from materials capable of withstanding enormous loads. In this respect, we are yet to find a replacement to metal. According to Petr Zhuk: “Many have tried to find a replacement, for instance, using composites based on Kevlar fibres. But, so far, no one has managed to complete a project without using metal structures.” The modern use of high-strength metals in high-rise buildings has partly been the result of their popularity in the military industry, car manufacturing and shipbuilding. These metals have also withstood the test of time in bridge building and in the construction of large-span farms, which led to the best practices applied in skyscraper construction today.

Such materials are ready for truly extreme tests. For instance, long steel products by Metalloinvest, used in the construction of Moscow City, have a high resistance to cold temperatures, which facilitates the trouble-free upkeep of buildings and structures even at temperatures as low as –70°С. Products made from high-strength metal brands undergo a cycle of thermo-mechanical tests and have a stable chemical composition. The building of a skyscraper means a high level of responsibility not only for the designers and builders, but also for the material suppliers.

“It all depends on the height. It is particularly important to avoid frame displacements, the vibrations of which can be noticeable and cause discomfort for people on the top floors. This is why skyscrapers progress only as far as steel making progresses.”

Alexander Tusnin

Professor of the Department of Metal and Wood Structures at the Moscow State University of Civil Engineering

Not a Revolution, But an Evolution

The tallest building in the world today is the 163-floor Burj Khalifa (828 m) in Dubai, built in 2010. However, a more ambitious project is already under way – there are grand plans to complete the Dubai Creek Tower for the World Expo-2020 exhibition in the UAE. The height of the main tower should rise 100m above the Burj Khalifa.

For stability, the Dubai Creek Tower designers rely on steel cables, secured onto the reinforced concrete core. One of the metal suppliers for the Tower is the Hamriyah Steel plant, which is part of Metalloinvest. It is a new enterprise, commissioned in 2010 with a planned capacity of 1 million tonnes of steel products per year. The tender was won because the plant’s products met the technological and cost requirements of the Dubai Creek Tower. For any project, the accurate calculation of the cost of construction work and further costs of operation are an absolute necessity, says Vladimir Neustruev. Moreover, skyscrapers have individual characteristics. “If one were to replace high-strength steels with conventional brands, the weight of the structures will increase significantly, which would require more complex and expensive foundations. This would result in either big overheads or less floors,” highlights Neustruev.

When calculating the supporting structures and foundations, suppliers must work with higher values of reliability factors. After 9/11, when the 400-metre sister towers of the World Trade Center collapsed in New York, the issue of protection from progressive collapse in the case of local damage to load-bearing structures is another factor that needs to be considered.

In addition, it is important not to forget that any high-rise building has a special degree of fire safety. It depends not only on the fire protection system itself, but also on many other factors.

“One of the important factors is the fire resistance of the skyscraper frame, which is achieved by processing metal with specialised materials. The World Trade Towers demonstrated the need for high-quality insulation. When building the towers, constructors used metal structures processed with synthetic thermal insulation materials instead of asbestos. The former’s fire resistance at extremely high temperatures, according to studies, did not match design requirements. If these requirements were met, many victims could have survived as the collapse would have been delayed by about four hours,” explains Petr Zhuk.

Then there are the issues of wind and seismic safety. The first high-rise buildings used passive protection systems, which increased the rigidity of the spatial framework. Yet, for several decades, we have utilised adaptive systems that adjust to the direction and strength of the seismic or wind impact. “This could be pre-stressed concrete or cables controlled by a computer,” says Vladimir Neustruev.

However, he adds, in all aspects of high-rise construction, there is an evolutionary rather than a revolutionary process. “We are yet to hear about fundamentally new solutions successfully implemented in the construction of high-rises. The most recent projects are carried out according to the standard scheme, which includes a metal frame, monolithic disks, and a glazed facade.”

Nevertheless, even without revolutions in this area, architects and builders thrive for new heights, and hence the skyscraper race continues.

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