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It's normal because architects are working more closely with engineers, bringing them in at the very start of the design process to assure the stability of their daredevil schemes and superhigh altitudes. "As the buildings get taller and taller, you really need the input of the structural engineer at the beginning," says Ysrael Seinuk, whose firm, Cantor-Seinuk, is the structural engineer for the Freedom Tower at the World Trade Center site. Towers have got not just taller but stranger--asymmetrical and askew. No need to worry though, says Charles Thornton of Thornton-Tomasetti Engineers, which worked on a new tower in Taipei, among many others. "Two new developments allow us to produce any shape anyone wants to do," he says. "One is the ability to 'build' a building on the computer with programs that even factor in the dimension of time. We can see how components react to stress over the years, so that building doesn't go out of plumb." The second is that with computers, engineers and architects can also produce accurate three-dimensional designs, then a 3-D model, which is easier for subcontractors to follow accurately than the old two-dimensional blueprints or specs. "We give that to the fabricators, the steel erector, the exterior wall façade supplier," says Thornton. "The 3D model makes for less error in the construction phase."
No matter what the exterior looks like, the skyscraper can be a problematic building--isolated, aloof from its neighbors and boring inside, a pancake stack of identical floor plates with a lobby at the bottom and maybe a restaurant at the top. For years now, Rem Koolhaas, the oracular Dutch architect and urban theorist, has conducted an unrelenting rhetorical campaign against the skyscraper. "The promise it once held," he wrote recently, "has been negated by repetitive banality [and] carefully spaced isolation."
Anybody who rides the elevator in an office or apartment building knows how true that is. So the interior space of the tall tower is lately subject to a complete reimagining. The most famous answer from Koolhaas has been his cantilevered proposal for the CCTV tower, headquarters of China's government television operation in Beijing. It's a building that somersaults over itself to provide the maximum space in which people can connect with one another. This year United Architects, an alliance of several architectural offices, entered a no less astonishing submission in a competition to design the Frankfurt, Germany, headquarters of the European Central Bank--an undulating sphere, 504 ft. high. Although it wasn't the winner, it made plain the radical direction in which things are moving.
The competition for the World Trade Center site, held in 2002, also made people aware, as never before, of how quickly architects are moving the skyscraper into uncharted territory. United Architects entered a widely seen proposal in the competition, an ensemble of five slightly inebriate towers. Some of them rise on the diagonal, and all of them eventually lean into one another and touch at their 60th floors. At that juncture they produce their most spectacular feature, a five-story corridor spanning the length of all five towers horizontally, making a fully enclosed loggia hundreds of feet long--a city street in midair.