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Posted Jul 2, 2007, 11:13 PM
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Join Date: May 2007
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The pursuit of new heights
Take a look at this article on NCS. I can see how this has become a controversial issue. What do you think of the Council on Tall Buildings and Urban Habitat standards? Do you think they should remain the same or should they be changed?
Images of the referenced buildings are included on the site.
http://www.newcityskyline.com/Thepursuitofnewheights.html
The pursuit of new heights
Monday, July 02, 2007
By Kelly Matlock
Chicago, IL, US (NCS) - It’s a safe bet to say that nine out of 10 people would have a uniform response to the question “what is a skyscraper?” or “what is a tall building?” At least in a general sense, it’s understood that these refer to buildings with great height or many more stories than their neighbors. Many people would consider these buildings at least 150 meters or 500 feet tall and will often call them “towers.”
But when architectural buffs discuss the issue on a more technical level, the conversation has increasingly turned into a debate: what is inferred by the term “tallest” and what exactly is included in the measurement of a building’s height?
Up until 1998, the tallest building status was essentially uncontested. Counting buildings as structures with floors throughout, and with antennas excluded, the Sears Tower in Chicago (designed by chief architect Bruce Graham and structural engineers Srinivasa “Hal” Iyengar and Fazlur Khan of Skidmore, Owings and Merrill) was considered the tallest.
When the Cesar Pelli-designed Petronas Twin Towers in Kuala Lumpur, Malaysia were built in ’98, controversy arose. While the Petronas’ spires extended nine meters higher than the roof of the Sears Tower, the highest habitable floor of Sears was more than 200 feet higher than the top floor in Petronas with its antennas even higher.
During this time of controversy over height, the Council on Tall Buildings and Urban Habitat (CTBUH), an international organization based at the Illinois Institute of Technology in Chicago, defined four categories in which the world’s tallest building can be measured. The first and most widely and officially used category by the architectural community is the height to the structural or architectural top, including spires and pinnacles, but not antennas, masts or flagpoles. The second category is the height to the highest occupied floor. The third is the height to the top of the roof, and the fourth is the height to the top of the antenna. In all of these categories, the height is measured from the sidewalk of the main entrance.
At that time, Petronas Towers held the record for the first category (to top of spire), and the original World Trade Towers, designed by Minoru Yamasaki, Emery Roth & Sons, held the fourth (to top of antenna). Months later, the Sears Tower added a new antenna and took 1st place in the fourth category. In 2003, architect C.Y. Lee’s Taipei 101 in Taiwan surpassed the record in the first three categories and became “tallest” in terms of height to the spire, height to the highest occupied floor and height to the top of the roof.
There’s also the question of where proposed and under-construction buildings come in. Do in-progress and expected buildings count in the competition for the tallest, or are they excluded from the race until they are officially complete? It seems to be a frequent debate in architecture with no clear cut answer.
As exhibited at the Skyscraper Museum in New York, a museum founded by architectural historian Carol Willis in 1996 as a place to celebrate “the business of skyscrapers and the interaction between buildings and cities,” the currently under construction Burj Dubai on the desert sands of Dubai will soon reign as the tallest building (if measured to the top of the spire).
Scheduled for completion in late 2008, the Skidmore, Owings & Merrill-designed Burj Dubai will most likely pass up Taiwan’s 509-meter, 1,671-foot Taipei 101 this summer. While its projected altitude remains a secret, the spire that stretches above the building’s 160 stories of apartments and office suites will climb at least 808 meters or 2,651 feet, making it more than twice the height of the Empire State Building and around 300 meters taller than Taipei 101.
There are several other towers now under construction that will also surpass the Taipei 101, considering the height to the architectural top or top of the spire. The Jakarta Tower under construction in Jakarta, Indonesia will rise 558 meters when completed in 2009, The Port Tower Complex in Pakistan should be finished within six years and is said to be 593 meters. The Chicago Spire is expected to begin construction in July and will stand 610 meters high upon completion scheduled for 2010. There is also the Sumida Tower in Japan, proposed for completion in 2011 and planned to be 613.5 meters. The Incheon Tower in Korea may become the tallest building, soon to rise 640 meters.
A few other towers throughout the world are under construction or planned to reach around 600 to 700 meters in height. But they may get even taller: Al Burj planned for Dubai might be 1200 meters, The proposed Mubarak al-Kabir Tower in Kuwait would be 1,001 meters. The proposed Murjan Tower in Manama, Bahrain is going to be 1,022 meters, and it is rumored that there is a proposed tower in London if approved and built, will be 1500 meters tall, nearly three times as tall as the Taipei 101.
The sprouting of taller and taller towers everywhere has also stirred up a lot of talk about elevators, as there would be no skyscrapers without elevators. Designing the vertical transport and fitting it into the compact core of mechanical system is a key part of a tower’s design development from the earliest stages. Elevators create a whole new contest between tall buildings: which building has the fastest elevator?
Taipei 101 is known to have two of the world’s fastest, which travel 3,333 feet per minute and can go from ground floor to the 89th floor in 39 seconds.
It is interesting to note how not only the standards for height have changed over the years, but the design trends, the locations of new development and the use of super-tall skyscrapers have changed too.
Until the 1990s, the tallest skyscrapers were almost always giant office buildings made of steel and erected in the United States. Today, like Burj Dubai, they are principally residential or mixed-use buildings made of concrete and glass or composite and located in Asia or the Mideast.
The motivation behind skyscrapers isn’t what it used to be either. While tall building construction has been widely acknowledged as being driven by economic factors in addition to the need for higher density in urban areas and concern for sustainable design, lately people seem to point towards a little thing called ego.
American.com writer Phillip Nobel recently wrote, “The old formula for what drives skyscraper construction—high density plus high land values equals high buildings—is quite undone by the new class of super-tall buildings, rising as they so often do from the wide-open spaces of unformed young cities.”
Still, the financial aspect of skyscraper construction will probably always be a major component of their development. Willis, founder of New York’s Skyscraper Museum, once said “my attachment to the skyscraper is a romantic notion, but my explanation for it is rational.” Willis elaborated on this in her book called “Form Follows Finance,” which talks about how, where and why skyscrapers are increasingly built—and her answer to all three questions involves money.
“Skyscrapers are businesses themselves. The first blueprint is always a balance sheet: if it’s not going to make money, it’s not going to get built,” says Willis.
In addition to the new trends behind how, why and where skyscrapers are built, the shapes of supertall skyscrapers have changed also, from basic rectangle-looking buildings with traditional materials, colors and ornamentation to buildings with all sorts of decoration, in odd shapes including the ever-popular twisting façade that is currently popping up more and more in new tower designs.
The advent of new and improved computer technology that allows three dimensional modeling has helped tremendously with the evolution in design.
The fun part of creating new designs for sky-high buildings does bring architects some new responsibilities and challenges. Architects must consider many issues when designing super-tall skyscrapers that they may not have to focus on when designing short buildings. Wind is a big one. Tall buildings must resist overturning due to lateral forces from wind, earthquakes or even their own weight. Beyond insuring against catastrophic failure, engineers and architects must design structures that do not flex too much, since movement can damage joints, cause leaks and even break windows and façade panels.
In the Burj Dubai exhibition at the Skyscraper Museum in New York, there is a short film on display in the gallery in which William F. Baker, partner in charge of structural engineering at SOM Chicago, explains how the building was engineered to “confuse the wind,” as its constantly changing shape diminishes wind forces which normally accumulate around a tall building.
As presentations like this show, architects are managing to outsmart science, or perhaps create new science, that allows them to design taller and taller buildings with new and improved façades, structures and technologies.
The obsession with spires and artful, innovative designs that stretch up to the sky is only growing, creating more and more argument over the definition of height.
As of now, it seems that most architectural groups accept and apply the Council for Tall Buildings and Urban Habitat standards—height is measured from the sidewalk at the main entrance of the building to the top of the spire or architectural top of the building, excluding antennas—however, it’s almost guaranteed that the definition of height will continue to change and evolve as buildings go higher and technology forges ahead to lead the way.
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