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Innovation - Life, Inspired

Episode 1: Building to Extremes
Special Report

Skyscrapers Then and Now

A Thoroughly Modern Structure

The skyscraper, icon of modernity and engineering prowess, came to dominate all major urban landscapes in the 20th century. Every city intent on asserting its presence as a cultural center and participant in world affairs threw its resources into constructing a tall building to anchor the downtown area and make the skyline instantly recognizable around the world. To individuals, a skyscraper rising alone above the crowd seems to hold a special allure -- even King Kong couldn't resist the tallest building around.

Although humans have always strived to erect awe-inspiring structures -- think of the pyramids, the Coliseum or the Taj Mahal -- it was not, until recently, feasible to construct buildings that were very tall. As floors were added to a building, the walls of the base had to be thickened to sustain the huge amounts of weight exerted downward by multiple stories stacked atop one another. This left little room on the ground floor and made such buildings impractical.

In the 19th century, however, advances in manufacturing iron and steel made it possible to support great amounts of weight without taking up much space. In addition, the invention of elevators allowed tenants to work on upper floors without having to walk up an inordinate amount of stairs. Other improvements and refinements made occupancy tolerable, so that working in a location far removed from the ground was not uncomfortable or inconvenient. Economic factors drove the construction of buildings that went up instead of out; as precious downtown space became more expensive the only way for buildings to expand was by going up.

Skyscraper construction truly emerged in the 20th century, and the United States dominated the discipline for most of that period. The field truly took off in the late 1920s, when three New York City builders entered into a feverish competition to erect the world's tallest structure. Those connected with the buildings eagerly sought the cachet that came with that distinction, and they were not above using trickery to outwit their competitors. Two buildings begun in 1929, the Chrysler Building and the Bank of Manhattan Tower, were designed for identical heights of 925 feet. After construction started, H. Craig Severance, architect of the Bank of Manhattan Tower, added two feet to his building's height and claimed it as the world's tallest. But William Van Alen, the Chrysler architect, had secretly secured permission to add a seven-story spire to his building. The spire was furtively assembled inside the upper floors of the building and quickly hoisted to the top one day in November 1929, reaching to a height of 1,048 feet. The Chrysler building's triumph was short-lived, however, as the 1,250-foot Empire State Building -- erected in a mere 410 days -- surpassed it by a wide margin just six months later.

Asia Takes The Lead

In the 1990s, the action shifted around the globe to Asia. Countries such as Malaysia and China wanted to make the statement that they had arrived as participants in world affairs, and would play integral roles in the global economy. Constructing the world's tallest building was a dramatic way for a city to announce its presence as a commercial and financial capital.

In 1996, the 88-story twin Petronas Twin Towers, named after a Malaysian oil company, were completed in Kuala Lumpur, Malaysia. Although the occupied portion of the building reaches only 1,229 feet, the spires reach to 1,483 feet -- or 33 feet higher than the Sears Tower. The Petronas Twin Towers' reign as tallest building was short-lived however. In the Republic of Taiwan, the Taipei 101 Tower, completed in 2003, eclipsed the Petronas Twin Towers by 184 feet. Located in Taiwan's capital city, the building is 101 stories high, comprising a series of stacked pagoda shapes. In Shanghai, China, another 101-floor building, known as the Shanghai World Financial Center, is under construction. This building, delayed by financial setbacks, is slated to be finished in 2007, and it may surpass the Taipei 101 Tower in height.

Safety Innovations in Asia

Asia is a perilous region in which to erect tall buildings because it is beset with earthquakes and typhoons, either of which can prove disastrous to a building with a structural weakness. To offset this threat, calculations must be precise and the precautions exhaustive -- changing a skyscraper's design or structure after construction begins is very expensive if possible at all.

The new Asia skyscrapers incorporate safety innovations to withstand the forces of nature. To endure earthquakes, the Taipei 101 Tower includes immense welded steel columns combined with a massive steel cage wrapped around the entire building that is designed to flex and bend to absorb seismic energy. (This design is meant to withstand the strongest earthquakes in a 2,500-year cycle.) To counteract the effects of wind, the same building has a "damping" device in the form of a 660-ton steel pendulum placed near the top of the structure.

U.S. elevator codes don't prescribe firefighter lifts. Instead, safety codes require elevators to automatically go to the ground floor if smoke is detected in the building. (Arriving firefighters can reactivate the cars using special keys.) This may change soon, however; the National Institute of Standards and Technology has come to preliminary conclusions that elevator use in emergency situations offers advantages to both occupants and firefighters. More research must be conducted before policy officially changes, however.

Recommendations After September 11

The September 11 attack raised many questions about skyscraper safety. To address these concerns, experts in professional organizations such as the Council on Buildings and Urban Habitat and the Institution of Structural Engineers, have issued recommendations to improve the performance of skyscrapers during emergencies. The main suggestions include:

- Incorporate alternative load paths so that weight will automatically shift to another load-bearing element if one component is taken out. The World Trade Center towers remained standing immediately after the planes hit because weight no longer borne by damaged columns was transferred to the giant truss on the roof. The subsequent fires eventually weakened the steel in remaining columns and the truss, but the delay in the collapse gave many people -- an estimated 20,000 -- time to escape.

- Set evacuation strategies that can accommodate many people simultaneously and protect them from smoke and fire. These innovations in planning, while low-tech, can greatly improve safety compared with buildings of earlier design. This includes allowing inhabitants to escape by both stairs and elevators that have adequate space. After the September 11 attack, experts at the Petronas towers designed and implemented an escape plan using the elevators that halved the evacuation time to 20 minutes. Those unable to walk down far enough to escape the fire can go to a smoke-proof waiting area for rescue by a service elevator. In the Taipei 101 Tower, each floor includes emergency escape corridors leading to fire-safe rooms, and there are outdoor balconies every eight floors allowing refuge. Asian buildings also have specially reinforced fire or "bomba" elevators that are dedicated exclusively to emergency crews and fire departments, allowing rapid access to fires and avoiding conflict with those trying to evacuate.

- Have both passive and active fire protection features. The passive features are mainly fire-resistant materials that will not be compromised by damage to the building. (At the World Trade Center, fireproofing material that had been sprayed onto the steel beams was knocked off by the impact of the planes and was thus ineffective). The active features mainly consist of sprinkler systems that automatically turn on during fires but should not be counted on for extreme events.

- Integrate building systems to provide on-site and remote information to the appropriate authorities. This allows both those on the scene and those at remote locations to get a complete picture of what is going on inside the building, where fires or damage has occurred, and where people may be trapped.

Most experts agree, however, that it is not practical to design skyscrapers to completely withstand devastating terrorist attacks, including being rammed by a fuel-laden jet airplane.

Others Join The Race to the Top

It appears the competition for the tallest building will continue as other nations join in. A considerable number of even taller buildings are at various stages of planning, although it is impossible to foresee which ones will make it past the drafting table. Tentative plans have been made for the construction of a building in the Arabian Gulf state of Dubai that will be 800 meters high -- easily smashing all current records.

A more likely prospect, however, should bring the title back to New York if only temporarily. The new Freedom Tower that will replace the World Trade Center is to be 1776 feet, or 541 meters. At this height, it would probably be the world's tallest building upon completion in 2008 or 2009. For a short while, at least, the race for the tallest building will have come full circle.

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