Famous construction – Willis Tower on the tubular metal structure

The Willis Tower is a famous building and a symbol of the city of Chicago, just as the Eiffel Tower is identified with Paris. The 110-story structure was the tallest building in the world until 1996.

In 1974, when the building was inaugurated, it was called SearsTower. In March 2009, Willis Group Holding, an insurance broker, rented part of the building and acquired the right to rename it. On July 16, 2009, the building was officially renamed the Willis Tower.

The team of architect Bruce Graham and structural engineer Fazlur Rahman Khan designed the building as nine square structures (each, in essence, a separate building), grouped in a 3 × 3 matrix. All nine structures rise to the 50th floor of the the building. Here the northwest and southeast structures end, and the remaining seven continue. On the 66th floor, those from the northeast and southwest stop, and on the 90th floor, those from the north, east and south. The structures in the center and west continue up to the 108th floor.

The Willis Tower was the first building to use the tubular structure invented by Khan. The innovative design was structurally and economically efficient, offered more space and could be taller than the Empire State Building. Also the costs were lower. This structural system proved extremely influential in the construction of skyscrapers. It has been used in most of the very tall buildings built since then, including the tallest building in the world, the Burj Khalifa.

The Willis Tower is a famous building – surface and use

With an area of ​​approximately 4,560,000 square meters, of which the leasable area is 3,800,000 square meters. The building houses numerous offices and commercial spaces, being an important business center for Chicago. In the building there are 25 kilometers of sanitary installations, 1500 kilometers of electrical cables and 145,000 lighting fixtures. The entire construction weighs more than 222,500 tons and cost more than 175 million dollars.

Welded steel frames were used that form vertical tubes that ensure the necessary rigidity to limit the force of the wind from the side. This system reduces the amount of construction steel required for a high-rise building.

The Willis Tower integrates into the skyline of the city of Chicago, proud and respectful. The exterior construction material shows very little wear, a sign of a durable construction. Many of its details allowed it to remain a modern symbol of the city center.