Did you know...? of the week: The Shake in Tall Buildings and Skyscrapers

The Shake (Skyscrapers)


Did you know...? All buildings move to a greater or lesser extent, whether high, low, or regardless of size. Although this movement is almost imperceptible to people, the reality is that we noted with greater intensity in the upper floors of tall buildings and skyscrapers. Strong winds occur in high-rise buildings a phenomenon known as "Shake" (oscillation Building on the vertical line). In any design process of a tall building, the team of architects and structural engineers must take into account numerous criteria not only in terms of support structure of the building itself, but also on the aerodynamic and static all with the aim of reducing the horizontal loads by wind action and give the building a greater stability for the welfare of the occupants. For this, make several models of different scales building subsequently undergoing extensive testing in the "wind tunnel".

above, the image of the tests that were done to the model of the Burj Khalifa in Dubai in the wind tunnel at the University of Ontario in Canada. In the left graph shows the behavior of the wind in the different sectors of the building facade, low, medium and high; below, numerous sensors attached to the inside of the model of the building, were placed carefully to check the behavior of the facade against the strong winds. However, a connecting cable to send data obtained powerful computers.

The tests in the wind tunnel used to prevent possible deficiencies in the structure or design of the facade before you placed the first stone. These tests will reveal the behavior tall buildings and skyscrapers with respect to strong winds and against typhoons or earthquakes, both individually and in relation to nearby buildings located nearby, in some cases tests are performed including with an enlarged detail specific termination shot top of the building, in order to hear more about their behavior in the strong wind. The results of the computer help certify that the building design itself can withstand extreme conditions by inclement weather to finally be able to carry out its construction. All this in order to avoid a possible disaster by structural collapse and subsequent crash.

above, the image of the two analyzes carried tall buildings, the Turning Torso in Malmo and the Burj Khalifa in Dubai. Both towers have become true collective architectural references in the world of skyscrapers in the beginning of this century, making a real show of architecture, engineering and vanguard down drawings of the different facades of the Turning Torso in which the image is never same.

To give two examples known to all, in the case of HSB Turning Torso in the Swedish city of Malmo, designed by Spanish architect and engineer Santiago Calatrava, which has 190 meters high, the tests in the wind tunnel reflected that the shock would not exceed 30 cm. in the vertical line. In the Burj Khalifa in Dubai, however, architectural height 828 meters, making it currently the world's tallest skyscraper, designed by Skidmore, Owings & Merrill LLP (SOM), the tests in the wind tunnel reflected the shaking would not exceed 125 cm. (1.25 meters).

up, shake Burj Khalifa in Dubai, with the oscillation stop building at the top, 125 cm. The oscillations produced by strong wind tear halfway up and go accusing As the building rises, down himenocallis image, a flower native to the Dubai desert that inspired the American architect Adrian Smith to design the skyscraper highest in the world.

Both structures have in common a very important element for the static function of each tower, the concrete core, circulate in the case of the Turning Torso and irregular hexagonal shape at the Burj Khalifa in Dubai. This central core made ​​of concrete adds stiffness to the structure as if it were made ​​of conventional steel. The construction system of reinforced concrete core was performed in both cases using a climbing formwork, slipform formerly called, the latter which was first used to erect the towers of Marina City residential design great Chicago architect Bertrand Goldberg.

Image HSB Turning Torso Copyright © HSB Malmo / Samark
The HSB Turning Torso, as its name suggests, is inspired by the figure of a human torso rotation. The external structural wall designed by Calatrava that runs vertically on the facade throughout, apart from transmitting the loads to the foundation and provide greater stability to the tower from the wind, gives the building great character and personality down, original sketch architect himself where the metaphor that is used for the design of your building.

In the first case, for the Turning Torso opened in 2005, Calatrava designed an outer steel structural wall by horizontal beams and other diagrid (loaded diagonal) that apart from providing great stability to the building facing the strong wind, help to spread the loads to the foundation. In the case of the Burj Khalifa in Dubai, which was opened five years later in 2010, we designed a giant Mega-spiral structure with "kicks" at different heights to get "cheat the wind" by the oscillations of the tower be as pronounced because of their superhuman dimensions.

above floor of Burj Khalifa in Dubai in the early levels. The hexagonal core reinforced concrete, if uneven, contains vertical circulation Ascesores, emergency stairs and facilities. This provides access to the three wings gallonadas forming Y-shaped 120 ° between them, down, striking image at the foot of the world's tallest skyscraper.

Curiously, the shock of the two buildings, 30 cm. and 125 cm. respectively is proportional to the height of each tower. Although the two separate floors of tall buildings oscillate reach a greater or lesser extent, the occupants hardly notice the feeling that the building moves the least. Not so, however, with the skyscrapers of the second Chicago school such as the John Hancock Center and the famous Sears Tower (Willis Tower), built using a steel-frame, where the oscillations are more than a fact and with which we must live. This shows that the skyscrapers are being improved with the new cutting edge technology, new building systems, new materials and new construction techniques that have made possible to build beautiful buildings but also becoming more resistant. Therefore, the reinforced concrete, thanks to its stiffness and employee in the central core, is presented as the best material of this century for the construction of high-rise buildings.

Image HSB Turning Torso Copyright © HSB Malmo / Ole Jais

The sad bombing of the Twin Towers happened on September 11th 2001 in New York City marked a before and after in the history of skyscrapers and the world. This tragic event has caused architects and engineers from around the world have had to rethink how to build a new high-rise buildings more safely. A good example might be the One World Trade Center design by David Childs of SOM American firm, which is currently being completed in the work of rebuilding Ground Zero in New York. This new skyscraper, which will become its 541 meters high at the tallest skyscraper in the United States of America, has the distinction of possessing a reinforced concrete superstructure in its core combined with a plot perimeter steel columns in the outer ring, making it one of the safest buildings in the world.

In Asia, where many earthquakes occur quite frequently, are real specialists in designing earthquake-proof buildings, strong winds and typhoons, as this geographical region has to live with this kind of adverse weather as usual for much the year, as evidenced by the Taipei Tower in Taiwan island where employment was a huge ball of counterweight on the ground 92, which counteracts the possible movements produced in the building, enduring earthquakes up 7 points on the Richter scale and winds of over 450 km / h.

Related post:

One World Trade Center
Manhattan, New York City, USA
Skidmore, Owings & Merrill LLP

Burj Khalifa (Burj Dubai)
Dubai, United Arab Emirates
Skidmore, Owings & Merrill, SOM

HSB Turning Torso
Malmo, Sweden
Santiago Calatrava

Taipei 101
Taipei, Taiwan
C. Y. Lee & Partners

References / Referencias

The Urban Towers Handbook
John Wiley&Sons, London, 2011
by Eric Firley and Julie Gimbal

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TURNING TORSO - Santiago Calatrava
Bellisco Ediciones, Madrid, 2008
by José Miguel Hernández Hernández
Español - English

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