What materials are used to build skyscrapers


From Babel to Taipei

People have been aiming high for thousands of years: the Great Pyramid, together with the other two pyramids of Giza, is the last remaining ancient wonder of the world and was originally almost 147 meters high. The Pharos lighthouse in Alexandria brought it to around 140 meters.

And according to the Old Testament, the Tower of Babel should have grown into heaven - which angered the Lord God so much that he confused people's language and made them diverge in all directions. Nevertheless, to the glory of God, they continued to build: the tallest church tower in the world measures 161 meters. It is in Ulm.

It will never be possible to completely clarify whether these buildings are the result of an addiction to fame and greatness or the desire to banish the fear of heights. What is certain is that not only sacred buildings have been scratching the clouds since the 19th century, but also high-rise buildings with apartments, offices, hotel rooms and television towers, many with a café called "Zur Schöne Aussicht".

At the same time, architects, politicians and urban planners are arguing about how socially acceptable, energetically sensible and, above all, how safe high-rise buildings are. The latter discussion was fueled by the attack on the World Trade Center in New York on September 11, 2001. Yet architects around the world are building taller, bolder, and more conspicuous.

The first skyscrapers

The history of huge cult buildings is thousands of years old, that of high secular buildings, on the other hand, is far more recent. The first of these emerged in the Middle Ages, when wealthy Italian citizens tried to rise above the cityscape with "gender towers". Gender towers are residential towers, with the height of which the respective family wanted to demonstrate their power.

Things only really got going when it came to skyscrapers when the fall-proof elevator, reinforced concrete and modern structural steels were developed in the middle of the 19th century.

With the help of the steel frame construction, the 42 meter high Home Insurance Building in Chicago was built from 1884 onwards. The Tribune Building and New York's Western Union Building in New York were significantly higher at 80 and 71 meters, respectively.

Skyscrapers need foundations that prevent the building from lying on its side when earth is moved. In the 241 meter high Woolworth Building, built from 1910 to 1913 in New York, concrete pillars form such a reinforced foundation. They reach under the street to the bedrock and keep the center of gravity of the building stable.

The pillars were built in underground air pressure chambers below the groundwater line, in which air pressure could be used to keep the water out of the chambers. This new process made the construction of the Woolworth Building possible at all. It is considered by many to be the first skyscraper.

Race to the top

The battle for the tallest building in the world began at the end of the 1920s: New York's Chrysler Building, completed in 1930, was awarded the title of "tallest building in the world" for a year. In the following year, first place went to the Empire State Building.

The protagonists of the first race were Walter Chrysler and John J. Raskob. Using tricks, both tried to stay ahead: Chrysler secretly had a 27-ton steel crown installed inside the shell, which cited the form elements of well-known automobiles and was supposed to tower over the Empire State Building as a roof top.

For his part, Raskob increased the Empire State Building from 80 to 85 floors and added a 60-meter-high crown that even zeppelins were supposed to attach to, but this never succeeded.

The Empire State Building was not replaced as the tallest building until 40 years later: The "Twin Towers" (417 or 415 meters) of the World Trade Center towered over Manhattan from 1972 onwards. They became a legend, although after just two years the Sears Tower in Chicago (442 meters) assumed the title of the tallest building in the world. From 1997 the Petronas Towers (452 ​​meters) in Malaysia's capital Kuala Lumpur were in the lead for a short time.

The Taipei Financial Center, completed in 2004, was the first skyscraper to exceed the 500-meter mark: it rises 508 meters into the sky and also sets standards in building safety, as there are frequent earthquakes and severe storms in Taiwan. But there is no end in sight to the high altitude race.

At the beginning of 2010, the Burj Khalifa skyscraper was inaugurated in Dubai. With a height of 828 meters, it far exceeds any other building in the world.

From the steam elevator to the superlift

Even without the invention of the elevator, it would have been possible to build tall. But expecting tenants to walk more than six flights of stairs at all times would hardly have made economic sense.

Elisha Graves Otis invented a steam powered elevator in 1852. He started a company that built transportation elevators and sold the first passenger elevator in New York in 1857. Serrated guide rails on each side of the elevator shaft held the elevator's gondola in place and clicked into place if the holding ropes failed - a first safety requirement for the construction of elevators and high-rise buildings.

By 1873 there were already 2000 passenger elevators, and electric motors replaced steam engines at the turn of the century. Today elevators are electronically upgraded machines. In skyscrapers, several of them work together ingeniously to transport thousands of people in the shortest possible time - at up to 15 meters per second.

In 1956, Frank Lloyd Wright planned a 1.5 kilometer high skyscraper with 130,000 residents on 528 floors. 56 nuclear-powered elevators were supposed to transport you and your guests. That remained a fantasy - but without powerful elevators, the giant buildings of Taipei, New York and Dubai would be nothing but fantasies.

Storms, tremors, acts of terror

The collapse of the World Trade Center (WTC) after the attack on September 11, 2001 once again put the question of the safety of high-rise buildings at the center of many discussions.

The construction of the WTC was undoubtedly safe. All external supports in the facades formed a tube with an edge length of more than 60 meters. Tubes are more resistant than comparable skeleton structures.

The WTC was even prepared for the impact of an airplane. However, the calculations were based on the largest machine that was available at the time of construction in 1972 - the Boeing 707.

Although large quantities of kerosene exploded in 2001 and the structure burned out from the enormous heat, the south tower was still 45 minutes after the aircraft impact, the north tower even 104 minutes. This saved the lives of thousands of people as they were able to leave the building during that time.

When building at the limits of what is possible, as at the Taipei Financial Center - and in a region where earthquakes and severe storms frequently occur - then the question arises of how much security can still be achieved. How can you get thousands of people out of the building in an emergency and provide access for rescue workers with heavy equipment?

The economy sets a limit to the urge. But the ambition of business people, politicians and architects to erect a monument sometimes goes beyond economic and safety concerns.