skyscraper: Definition and Much More from Answers.com

n.

A very tall building.

Background

There is no precise definition of how many stories or what height makes a building a skyscraper. "I don't think it is how many floors you have. I think it is attitude," architect T. J. Gottesdiener told the Christian Science Monitor. Gottesdiener, a partner in the firm of Skidmore, Owings & Merrill, designers of numerous tall buildings including the Sears Tower in Chicago, Illinois, continued, "What is a skyscraper? It is anything that makes you stop, stand, crane your neck back, and look up."

Some observers apply the word "skyscraper" to buildings of at least 20 stories. Others reserve the term for structures of at least 50 stories. But it is widely accepted that a skyscraper fits buildings with 100 or more stories. At 102 stories, the Empire State Building's in New York occupied height reaches 1,224 ft (373 m), and its spire, which is the tapered portion atop a building's roof, rises another 230 ft (70 m). Only 25 buildings around the world stand taller than 1,000 ft (300 m), counting their spires, but not antennas rising above them.

The tallest freestanding structure in the world is the CN Tower in Toronto, Canada, which rises to a height of 1,815 ft (553 m); constructed to support a television antenna, the tower is not designed for human occupation, except for a restaurant and observation deck perched at 1,100 ft (335 m). The world's tallest occupied structure is the Petronas Twin Towers in Kuala Lumpur, Malaysia, which reach a height of 1,483 ft (452 m), including spires. The Sears Tower in Chicago boasts the highest occupied level; the roof of its 110th story stands at 1,453 ft (443 m).

In some ways, super-tall buildings are not practical. It is cheaper to build two half-height buildings than one very tall one. Developers must find tenants for huge amounts of space at one location; for example, the Sears Tower encloses 4.5 million square feet (415,000 square meters). On the other hand, developers in crowded cities must make the fullest possible use of limited amounts of available land. Nonetheless, the decision to build a dramatically tall building is usually based not on economics, but on the desire to attract attention and gain prestige.

History

Several technological advances occurred in the late nineteenth century that combined to make skyscraper design and construction possible. Among them were the ability to mass produce steel, the invention of safe and efficient elevators, and the development of improved techniques for measuring and analyzing structural loads and stresses. During the 1920s and 1930s, skyscraper development was further spurred by invention of electric arc welding and fluorescent light bulbs (their bright light allowed people to work farther from windows and generated less heat than incandescent bulbs).

Traditionally, the walls of a building supported the structure; the taller the structure, the thicker the walls had to be. A 16-story building constructed in Chicago in 1891 had walls 6 ft (1.8 m) thick at the base. The need for very thick walls was eliminated with the invention of steel-frame construction, in which a rigid steel skeleton supports the building's weight, and the outer walls are merely hung from the frame almost like curtains. The first building to use this design was the 10-story Home Insurance Company Building, which was constructed in Chicago in 1885.

The 792-ft (242-m) tall Woolworth Building, erected in New York City in 1913, first combined all of the components of a true skyscraper. Its steel skeleton rose from a foundation supported on concrete pillars that extended down to bedrock (a layer of solid rock strong enough to support the building), its frame was braced to resist expected wind forces, and its high-speed elevators provided both local and express service to its 60 floors.

In 1931, the Empire State Building rose in New York City like a 1,250-ft (381-m) exclamation point. It would remain the world's tallest office building for 41 years. By 2000, only six other buildings in the world would surpass its height.

Raw Materials

Reinforced concrete is one important component of skyscrapers. It consists of concrete (a mixture of water, cement powder, and aggregate consisting of gravel or sand) poured around a gridwork of steel rods (called rebar) that will strengthen the dried concrete against bending motion caused by the wind. Concrete is inherently strong under compressive forces; however, the enormous projected weight of the Petronas Towers led designers to specify a new type of concrete that was more than twice as strong as usual. This high-strength material was achieved by adding very fine particles to the usual concrete ingredients; the increased surface area of these tiny particles produced a stronger bond.

The other primary raw material for skyscraper construction is steel, which is an alloy of iron and carbon. Nearby buildings often limit the amount of space available for construction activity and supply storage, so steel beams of specified sizes and shapes are delivered to the site just as they are needed for placement. Before delivery, the beams are coated with a mixture of plaster and vermiculite (mica that has been heat-expanded to form sponge-like particles) to protect them from corrosion and heat. After each beam is welded into place, the fresh joints are sprayed with the same coating material. An additional layer of insulation, such as fiberglass batting covered with aluminum foil, may then be wrapped around the beams.

To maximize the best qualities of concrete and steel, they are often used together in skyscraper construction. For example, a support column may be formed by pouring concrete around a steel beam.

A variety of materials are used to cover the skyscraper's frame. Known as "cladding," the sheets that form the exterior walls may consist of glass, metals, such as aluminum or stainless steel, or masonry materials, such as granite, marble, or limestone.

Design

Design engineers translate the architect's vision of the building into a detailed plan that will be structurally sound and possible to construct.

Designing a low-rise building involves creating a structure that will support its own weight (called the dead load) and the weight of the people and furniture that it will contain (the live load). For a skyscraper, the sideways force of wind affects the structure more than the weight of the building and its contents. The designer must ensure that the building will not be toppled by a strong wind, and also that it will not sway enough to cause the occupants physical or emotional discomfort.

Each skyscraper design is unique. Major structural elements that may be used alone or in combination include a steel skeleton hidden behind non-load-bearing curtain walls, a reinforced concrete skeleton that is in-filled with cladding panels to form the exterior walls, a central concrete core (open column) large enough to contain elevator shafts and other mechanical components, and an array of support columns around the perimeter of the building that are connected by horizontal beams to one another and to the core.

Because each design is innovative, models of proposed super tall buildings are tested in wind tunnels to determine the effect of high wind on them, and also the effect on surrounding buildings of wind patterns caused by the new building. If tests show the building will sway excessively in strong winds, designers may add mechanical devices that counteract or restrict motion.

In addition to the superstructure, designers must also plan appropriate mechanical systems such as elevators that move people quickly and comfortably, air circulation systems, and plumbing.

The Construction Process

Each skyscraper is a unique structure designed to conform to physical constraints imposed by factors like geology and climate, meet the needs of the tenants, and satisfy the aesthetic objectives of the owner and the architect. The construction process for each building is also unique. The following steps give a general idea of the most common construction techniques.

The substructure

• Construction usually begins with digging a pit that will hold the foundation. The depth of the pit depends on how far down the bedrock lies and how many basement levels the building will have. To prevent movement of the surrounding soil and to seal out water from around the foundation site, a diaphragm wall may be constructed before the pit is dug. This is done by digging a deep, narrow trench around the perimeter of the planned pit; as the trench is dug, it is filled with slurry (watery clay) to keep its walls from collapsing. When a section of trench reaches the desired depth, a cage of reinforcing steel is lowered into it. Concrete is then pumped into the trench, displacing the lighter slurry. The slurry is recovered and used again in other sections of the trench.
• In some cases, bedrock lies close to the surface. The soil on top of the bedrock is removed, and enough of the bedrock surface is removed to form a smooth, level platform on which to construct the building's foundation. Footings (holes into which the building's support columns can be anchored) are blasted or drilled in the bedrock. Steel or reinforced concrete columns are placed in the footings.
• If the bedrock lies very deep, piles (vertical beams) are sunk through the soil until they are embedded in the bedrock. One technique involves driving steel piles into place by repeatedly dropping a heavy weight on their tops. Another technique involves drilling shafts through the soil and into the bedrock, inserting steel reinforcing rods, and then filling the shafts with concrete.
• A foundation platform of reinforced concrete is poured on top of the support columns.

The superstructure and core

Once construction of a skyscraper is underway, work on several phases of the structure proceeds simultaneously. For example, by the time the support columns are several stories high, workers begin building floors for the lower stories. As the columns reach higher, the flooring crews move to higher stories, as well, and finishing crews begin working on the lowest levels. Overlapping these phases not only makes the most efficient use of time, but it also ensures that the structure remains stable during construction.

• If steel columns and cross-bracing are used in the building, each beam is lifted into place by a crane. Initially, the crane sits on the ground; later it may be positioned on the highest existing level of the steel skeleton itself. Skilled workers either bolt or weld the end of the beam into place (rivets have not been used since the 1950s). The beam is then wrapped with an insulating jacket to keep it from overheating and being weakened in the event of a fire. As an alternative heat-protection measure in some buildings, the steel beams consist of hollow tubes; when the superstructure is completed, the tubes are filled with water, which is circulated continuously throughout the lifetime of the building.
• Concrete is often used for constructing a building's core, and it may also be used to construct support columns. A technique called "slip forming" is commonly used. Wooden forms of the desired shape are attached to a steel frame, which is connected to a climbing jack that grips a vertical rod. Workers prepare a section of reinforcing steel that is taller than the wooden forms. Then they begin pouring concrete into the forms. As the concrete is poured, the climbing jack slowly and continuously raises the formwork. The composition of the concrete mixture and the rate of climbing are coordinated so that the concrete at the lower range of the form has set before the form rises above it. As the process continues, workers extend the reinforcing steel grid that extends above the formwork and add extensions to the vertical rod that the climbing jack grips. In this way, the entire concrete column is built as a continuous vertical element without joints.
• In a steel-skeleton building, floors are constructed on the layers of horizontal bracing. In other building designs, floors are supported by horizontal steel beams attached to the building's core and/or support columns. Steel decking (panels of thin, corrugated steel) is laid on the beams and welded in place. A layer of concrete, about 2-4 in (5-10 cm) thick, is poured on the decking to complete the floor.

The exterior

• In most tall buildings, the weight of the structure and its contents is borne by the support columns and the building's core. The exterior walls themselves merely enclose the structure. They are constructed by attaching panels of such materials as glass, metal, and stone to the building's framework. A common technique is to bolt them to angle brackets secured to floor slabs or support columns.

Finishing

• When a story of the building has been enclosed by exterior walls, it is ready for interior finishing. This includes installation of such elements as electrical wires, telephone wires, plumbing pipes, interior walls, ceiling panels, bathroom fixtures, lighting fixtures, and sprinkler systems for fire control. It also includes installation of mechanical components like elevators and systems for air circulation, cooling, and heating.
• When the entire superstructure has been completed, the top of the building is finished by installing a roof. This may be built much like a floor, and then waterproofed with a layer of rubber or plastic before being covered with an attractive, weather—resistant layer of tiles or metal.

Quality Control

Various factors are taken into consideration when assuring quality control. Because of the huge scale of skyscrapers, a small positioning error at the base will be magnified when extended to the roof. In addition to normal surveying instruments, unusual devices like global positioning system (GPS) sensors and aircraft bombsights may be used to verify the placement and alignment of structural members.

Soil sensors around the building site are used to detect any unexpected earth movement caused by the construction activity.

Byproducts/Waste

Excavation of the foundation pit and basement levels require the removal of enormous amounts of dirt. When the 110-story World Trade Center towers were built in New York in the early 1970s, more than I million cubic yards (765,000 cubic meters) of soil and rock were removed and dumped in the Hudson River to create 23.5 acres (95,100 square meters) of new land, on which another skyscraper was later constructed.

The Future

Plans have been developed for several new skyscrapers that would break existing height records. For example, a 108-story building at 7 South Dearborn Street in Chicago, expected to be completed by 2004, will be 1,550 ft (473 m) tall. It will provide 43 acres (174,000 square meters) of enclosed space on a lot only 200 ft (61 m) square.

In 1956, American architect Frank Lloyd Wright announced plans for a mile-high (1.6-km tall) skyscraper in which 100,000 people could work. In 1991, another American architect, Dr. Eugene Tsui, designed a 2-mile (3,220-m) tall building that would provide space for living, working, and recreation for 1,000,000 people. Although such buildings may be theoretically constructable, they are currently impractical. For example, human comfort levels limit elevator speeds to no more than 3,000 ft/min (915 m/min). To accommodate the 100,000 people working in Wright's proposed structure, the number of elevator shafts would have taken up too large a portion of the building's area.

Improvements in elevator technology will be important for future skyscraper designs. Self-propelled, cableless elevator cars that move horizontally, as well as vertically, have been proposed, but are still under development. Computerized car dispatching systems using fuzzy logic could be refined to carry people more efficiently by grouping passengers whose destinations are near each other.

Where to Learn More

Books

Books Dunn, Andrew. Structures: Skyscrapers. New York: Thomson Learning, 1993.

Michael, Duncan. How Skyscrapers Are Made. New York: Facts on File Publications, 1987.

Periodicals

Hayashi, Alden M. "The Sky's the Limit." Scientific American Presents: Extreme Engineering (Winter 1999): 66 ff.

Richey, Warren. "New Rush of Buildings Reaching for the Clouds." The Christian Science Monitor (July 8, 1998): 1.

Other

Dankwa, E. T. New York Skyscrapers.http://mx3.xoom.com/iNetwork/NYC (March 2000).

"Ultima's Tower, Two-Mile High Sky City." Tsui Design & Research.http://www.tdrinc.com/ultima.html (March 2000).

[Article by: Loretta Hall]

Origin: 1883

Before it became a building, Americans knew skyscraper as "a high-flying bird" (1840), "a tall hat or bonnet" (1847), or "a high fly ball in baseball" (1866). But in 1883, a visionary writer in American Architect and Building News declared that "a public building should always have something towering up above all in its neighborhood.... This form of sky-scraper gives that peculiar refined, independent, self-contained, daring, bold, heaven-reaching, erratic, piratic, Quixotic, American thought ('young America with his lack of veneration'). The capitol building should always have a dome. I should raise thereon a gigantic 'sky-scraper,' contrary to all precedent in practice, and I should trust to American constructive and engineering skill to build it strong enough for any gale." We have built skyscrapers ever since.

In early America, the steeples of the churches reached closest to the heavens. In the mid-nineteenth century, the state capitols raised themselves ever higher. Even county courthouses attained new heights. But by the end of the century, both church and state stood in the shade of the commercial skyscraper.

And for commercial developers it was not enough to take conventional construction to its upper limit, ten or eleven stories with thick load-bearing walls. American "constructive and engineering skill" enabled us to reach higher. We used iron to reinforce the masonry walls, then to support the floors, then to support both floors and walls. Finally we scrapped the iron entirely and replaced it with a riveted steel skeleton, and buildings were at last free to rise to any height.

In the 1890s, fifteen stories was high for a skyscraper, but the twentieth century soared much higher. In 1913, the Woolworth Building in New York City reached sixty stories. That was overshadowed by New York's Empire State Building in 1931, at 102 stories, which in turn yielded in 1974 to Chicago's Sears Tower, at 110 stories--1454 feet tall.

Very tall multistoried building. The term originally applied to buildings of 10 – 20 stories, but now generally describes high-rises of more than 40 – 50 stories. James Bogardus (1800 – 1874) built the pioneering Cast Iron Building, New York (1848), with a rigid iron frame providing the main support for upper-floor and roof loads. The refinement of the Bessemer process for making steel (lighter and stronger than iron) made extremely tall buildings possible. Chicago's Home Insurance Co. Building (1884 – 85), by William Le Baron Jenney (1832 – 1907), was the first tall building to use a steel skeleton. Structurally, skyscrapers consist of a substructure supported by a deep foundation of piles or caissons beneath the ground, an aboveground superstructure of columns and girders, and a curtain wall hung on the structural framework. Tube structures, braced tubes, and trussed tubes were developed to give skyscrapers the ability to resist lateral wind and seismic forces. The bundled-tube system, developed by Fazlur Khan (1928 – 1982), uses narrow steel tubes clustered together to form exceptionally rigid columns, and has been used to build some of the world's tallest skyscrapers (e.g., Sears Tower). Skyscraper design and decoration have passed through several stages: Louis Sullivan emphasized verticality; the firm of McKim, Mead, & White (see Charles F. McKim, Stanford White) stressed Neoclassicism. The International Style was ideally suited to skyscraper design. Originally a form of commercial architecture, skyscrapers have increasingly been used for residential purposes as well. See also setback.

For more information on skyscraper, visit Britannica.com.

Skyscrapers entered American parlance around 1890, describing ten-to fifteen-story commercial buildings mostly in Chicago and New York. Dependent on the passenger elevator, telephone, and incandescent bulb for internal circulation, communication, and illumination, the structural potential of its steel frame ensured that the economic benefit of multiplying lot size twenty, fifty, or one hundred times would render municipal height restrictions obsolete. Well before New York's 1913 Woolworth Building opened at 792 feet (54 stories), the world's tallest edifice excepting the Eiffel Tower in Paris, it was a social convention to wonder if the only limit to upward growth were the heavens themselves.

Artistic hesitation characterized skyscraper design from the beginning, less so in Chicago than in New York. Although skyscrapers' determining features were steel and height, architects were inclined to hide steel inside highly decorated, thick masonry walls. In addition, they negated height by wrapping every few stories with a protruding cornice interrupting vertical flow or by periodically shifting styles, so, as a building ascended, it resembled a stack of small structures. Those willing to embrace height tended to base form on historical analogies, usually French gothic cathedrals or Italian medieval towers.

In Chicago, Louis Sullivan referred to the classical column, but in his pioneering search for a self-referential skyscraper aesthetic, he transformed base, shaft, and capital into commercial ground floor, office tier, and attic for ancillary services, each function indicated externally. By recessing windows and walls a few inches behind columns and mullions, he privileged vertical elements of the frame to create, he wrote in 1896, "a proud and soaring thing" that was "every inch of it tall." Although highly regarded by critics, Sullivan's "system of vertical construction" was not widely adopted by architects, not even his Chicago School (c. 1885–1915) colleagues, whose so-called "utilitarian" building facades, less ornamented and more fenestrated than Sullivan's, closely followed in composition the grid pattern of the frame, which in reality is nondirectional.

Chicago School buildings were America's principal contribution to the formative stages of what was soon labeled "modern architecture." The implication, which might be encapsulated in the phrase "form follows structure," was disregarded in the United States during the 1920s, but it was taken up in Europe, particularly in Germany, where in 1921 and 1922 Ludwig Mies van der Rohe proposed free-form skyscrapers entirely encased with glass panels clipped to the edges of floor slabs. Of the 265 entries from 23 countries to the 1922 Chicago Tribune headquarters competition, 37 were German, notable among them Walter Gropius and Adolf Meyer's grid of reinforced concrete completely filled with windows. These and other European designs conclusively demonstrated what Chicagoans had almost perceived. Since load-bearing walls were structurally unnecessary, a skyscraper's facade could be reduced to little more than frame and glazing. The lesson was ignored when the Tribune Company selected Raymond Hood and John Mead Howells's decidedly unglassy, neogothic cousin to the Woolworth Building.

Until large-scale private sector construction halted during the Great Depression, American skyscrapers were either historical pastiches or tips of the hat to European art deco. Most famous were New York's Chrysler, Empire State, and Rockefeller Center buildings (of 1930 and 1931), featuring diagonal or zigzag "jazz age" ornament and equal amounts of glass and masonry in alternating vertical or horizontal strips forming crisp, rectilinear facades that nonetheless hide the frame. Two exceptions were noteworthy: Hood's 1929–1931 McGraw-Hill Building, designed with André Fouilhoux, in New York; and William Lescaze's 1929–1932 Philadelphia Savings Fund Society Building, designed with George Howe. Both were in what was labeled "the international style," which made structurally determined form something of a fetish.

It was fitting that the European émigrés Fouilhoux (from Paris) and Lescaze (from Zurich) figured prominently in the reconfiguration of American skyscrapers, because a third European, Mies van der Rohe, who arrived in Chicago in 1938, almost single-handedly completed the process, beginning with his 1946–1949 Promontory Apartments. More than any other edifice, his 1954–1958 Seagram Building in New York made the flatroofed, glass-walled, steel-or concrete-framed, minimally ornamented box a corporate signature as well as an indication that derivations of European modernism had captured the mainstream of American architecture.

A comparison of the two McGraw-Hill Buildings in New York suggests how much had changed since 1929. The first, by Hood with Fouilhoux, is bluish-green glazed terra-cotta and steps back five times before reaching its penthouse, which is sided with huge firm-name graphics. Its thirty-five richly textured, horizontally articulated stories complement the vertical thrust of the elevator shafts and stairwell. Although resolutely international in style, it resembles no other building. The four identical facades of the second McGraw-Hill Building, built in 1973 by Harrison, Abramovitz, and Harris, soar without interruption or variation through forty-five stories of closely spaced reddish granite columns. Devoid of graphics, it is a clone of the flanking Celanese and Exxon Buildings by the same architects. In less than half a century, collective anonymity replaced architectural individuality in every American city.

The low profile adopted by American corporations after World War II gave way in the 1980s to a more assertive public posture expressed architecturally in post-modernism (POMO): the return of polychrome, ornament, and historical reference enlivened by mixtures of nonorthogonal with rectilinear geometries. Rejecting the Mies-inspired modernist box and companion frame-based aesthetic, POMO recaptured a spirit of experimentation akin to that of the European 1920s but enhanced by an array of new materials and technologies, including computer-assisted design. The sky was again the limit in terms not of height but of artistic possibility.

Globalization of capital internationalized the profession. For example, four architects were invited in 2000 to submit proposals for a new New York Times headquarters: Norman Foster of London; Renzo Piano with offices in Paris and Genoa; Cesar Pelli, the Argentina-born dean of the Yale School of Art and Architecture; and Frank Gehry, a Toronto native residing in California. Gehry produced a twisting, undulating, concave and convex agglomeration of sinewy, computer-generated, non-Euclidean shapes that appears to be one tower or three, depending on the viewer's vantage point. Like the other submissions, it makes no reference except for signage to site or function, suggesting that any one of the four could be erected anywhere to serve any purpose. Sharing only the absence of similarity, they are as far removed from the modernist box as that was from the Woolworth Building.

During the course of a century, an American commercial building type, stylistically conditioned by historical precedent or by the steel frame, became an omnifunctional symbol of globalization conditioned only by architectural imagination. Technical limits to skyscraper height may be approaching, but form has no limits at all.

Bibliography

Goldberger, Paul. The Skyscraper. New York: Knopf, 1981.

Scuri, Piera. Late-Twentieth-Century Skyscrapers. New York: Van Nostrand Reinhold, 1990.

Twombly, Robert. Power and Style: A Critique of Twentieth-Century Architecture in the United States. New York: Hill and Wang, 1995.

Van Leeuwen, Thomas A. P. The Skyward Trend of Thought: The Metaphysics of the American Skyscraper. Cambridge, Mass.: MIT Press, 1988.

A skyscraper described in a song from the musical Oklahoma as "'Bout as high as a building ought to go" was in Kansas City, Missouri, and it was seven stories high. About the same time as the action in Oklahoma, another Midwestern city, Chicago, Illinois, boasted the earliest buildings recognized as skyscrapers today, which were two or three times as high.

The development of the skyscraper is often viewed as a consequence of the elevator. Elevators did permit buildings as tall as 10 to 16 stories, but lower floors were almost unusable. Concrete walls had to be 6 m (20 ft) thick to support the upper stories. The true key to the skyscraper was the steel frame that supported the walls and floors. Even so, the tallest office building to the end of the 19th century, the Park Row Building in New York City, was only 132 m (435 ft) high, half as tall as the Eiffel Tower, built around the same time. Also, early hydraulic elevators were only effective up to about 20 stories. Modern high-speed cable elevators, when introduced in 1900, greatly facilitated the construction of what we would view today as skyscrapers.

William Le Baron Jenney in Chicago first used a mixture of cast iron and steel to support a tall office building, the Home Insurance Building. Soon he and other Chicago architects were using all-steel frames. What they mounted on the frames, however, was often a tall version of a Classic Revival building. Louis Sullivan, the Chicago architect who designed the first spare, modern looking buildings and who is best known today, was not a success during most of his career. His turn-of-the-century buildings that showed clearly the influence of the steel frameworks in vertical and horizontal lines were not acclaimed at the time, and Sullivan died in poverty in 1924 after years with no work. His influence lived on, however, as a result of his teaching.

In the 20th century, the largest number of tall skyscrapers were built in New York City, but Chicago also had its share of famous skyscrapers. Today Chicago still has the tallest building in the United States, the Sears Tower. Today, however, the tallest skyscraper in the world is the Taipei Financial Center in Taiwan, at 508 m (1667 ft); it was completed in 2003.

Taipei 101 is the world's tallest completed skyscraper.

The Award Winning 30th St Mary's Axe (The Gherkin) in London is an example of modern environmental friendly skyscrapers

Emirates Towers in

Dubai

, currently the tallest and fourth tallest completed skyscrapers in the Middle East

The Turning Torso skyscraper in Malmö, Sweden. It is the second tallest residential skyscraper in Europe. The tower was completed in 2005.

The Freedom Tower, under construction in New York, will be the tallest building in the U.S. when completed in 2010, standing at 541 m (1,776 ft) in height. However, the Chicago Spire, expected to be completed by 2010, is expected to stand at 610 m (2,000 ft)

The

JP Morgan Chase Tower

in Houston, Texas at 305m is the tallest five sided tower in the world.

A skyscraper is a very tall, continuously habitable building. There is no official definition or a precise cutoff height above which a building may clearly be classified as a skyscraper. However, as per usual practice in most cities, the definition is used empirically, depending on the relative impact of the shape of a building to a city's overall skyline. Thus, depending on the average height of the rest of the buildings and/ or structures in a city, even a building of 80 meters height (approximately 262 ft) may be considered a skyscraper provided that it clearly stands out above its surrounding built environment and significantly changes the overall skyline of that particular city.

The word skyscraper originally referred to a nautical term tall mast or its main sail on a sailing ship. The term was first applied to buildings in the late 19th century as a result of public amazement at the tall buildings being built in Chicago, Detroit and New York City.

The structural definition of the word skyscraper was refined later by architectural historians, based on engineering developments of the 1880s that had enabled construction of tall multi-story buildings. This definition was based on the steel skeleton—as opposed to constructions of load-bearing masonry, which passed their practical limit in 1891 with Chicago's Monadnock Building. Philadelphia's City Hall, completed in 1901, still holds claim as the world's tallest load-bearing masonry structure at 167 m (548 ft). The steel frame developed in stages of increasing self-sufficiency, with several buildings in Chicago and New York advancing the technology that allowed the steel frame to carry a building on its own. Today, however, many of the tallest skyscrapers are built almost entirely with reinforced concrete. Pumps and storage tanks maintain water pressure at the top of skyscrapers.

A loose convention in the United States now draws the lower limit of a "skyscraper" at 150 meters (500 ft). A skyscraper taller than 300 meters (984 ft) may be referred to as supertall. In the United States, the supertall convention is 100 stories, which is equal to 1,000 feet. Shorter buildings are still sometimes referred to as skyscrapers if they appear to dominate their surroundings.

The somewhat arbitrary term skyscraper should not be confused with the slightly less arbitrary term highrise, defined by the Emporis Standards Committee as "A high-rise building is a multi-story structure with at least 12 floors or 35 meters (115 feet) in height." ^[1]. All skyscrapers are highrises, but only the tallest highrises are skyscrapers. Habitability separates skyscrapers from towers and masts. Some structural engineers define a highrise as any vertical construction for which wind is a more significant load factor than weight is. Note that this criterion fits not only highrises but some other tall structures, such as towers.

The word skyscraper often carries a connotation of pride and achievement. The skyscraper, in name and social function, is a modern expression of the age-old symbol of the world center or axis mundi: a pillar that connects earth to heaven and the four compass directions to one another.^[2]

History

Modern skyscrapers are built with materials such as steel, glass, reinforced concrete and granite, and routinely utilize mechanical equipment such as water pumps and elevators. Until the 19th century, buildings of over six stories were rare, as having great numbers of stairs to climb was impractical for inhabitants, and water pressure was usually insufficient to supply running water above  m ( ft). However, despite the lack of sanitation, the first highrise housing dates back to the 1600s in some places. In Edinburgh, Scotland, for example, a defensive city wall defined the boundaries of the city. Due to the restricted land area for development, the houses increased in height instead. Buildings of 11 stories were common, and there are records of buildings as high as 14 stories. Many of the stone-built structures can still be seen today in the old town of Edinburgh.

The oldest iron framed building in the world is The Flaxmill (also locally known as the "Maltings"), in Shrewsbury, England. Built in 1797, it is seen as the "grandfather of skyscrapers” due to its fireproof combination of cast iron columns and cast iron beams developed into the modern steel frame that made modern skyscrapers possible. Unfortunately, it lies derelict and needs much investment to keep it standing. On 31 March 2005, it was announced that English Heritage would buy the Flaxmill so that it could be redeveloped.

The first skyscraper was the ten-story Home Insurance Building in Chicago, built in 1884–1885. While its height is not considered unusual or very impressive today, the architect, Major William Le Baron Jenney, created the first load-bearing structural frame. In this building, a steel frame supported the entire weight of the walls, instead of load-bearing walls carrying the weight of the building, which was the usual method. This development led to the "Chicago skeleton" form of construction. After Jenney's accomplishment the sky was truly the limit as far as building was concerned.

Sullivan's Wainwright Building building in St. Louis, 1890, was the first steel frame building with soaring vertical bands to emphasize the height of the building, and is, therefore, considered by some to be the first true skyscraper.

The United Kingdom also had its share of early skyscrapers. The first building to fit the engineering definition, meanwhile, was the then largest hotel in the world, the Grand Midland Hotel, now known as St Pancras Chambers in London, opened in 1873 with a clock tower 82 metres (269 ft) in height. The 12-floor Shell Mex House in London, at 58 metres (190 ft), was completed a year after the Home Insurance Building and managed to beat it in both height and floor count. 1877 saw the opening of the Gothic revival style Manchester Town Hall by Alfred Waterhouse. Its 87-metre-high clock and bell tower dominated that city's skyline for almost a century.

Most early skyscrapers emerged in the land-strapped areas of Chicago, London, and New York toward the end of the 19th century. London builders soon found building heights limited due to a complaint from Queen Victoria, rules that continued to exist with few exceptions until the 1950s; concerns about aesthetics and fire safety had likewise hampered the development of skyscrapers across continental Europe for the first half of the twentieth century (with the notable exceptions of the 26-storey Boerentoren in Antwerp, Belgium, built in 1932, and the 31-storey Torre Piacentini in Genoa, Italy, built in 1940). After an early competition between New York City and Chicago for the world's tallest building, New York took a firm lead by 1895 with the completion of the American Surety Building. Developers in Chicago also found themselves hampered by laws limiting height to about 40 storeys, leaving New York to hold the title of tallest building for many years. New York City developers then competed among themselves, with successively taller buildings claiming the title of "world's tallest" in the 1920s and early 1930s, culminating with the completion of the Chrysler Building in 1930 and the Empire State Building in 1931, the world's tallest building for forty years. From the 1930s onwards, skyscrapers also began to appear in Latin America (São Paulo, Caracas, Mexico City) and in Asia (Tokyo, Shanghai, Hong Kong, Singapore).

Immediately after World War II, the Soviet Union planned eight massive skyscrapers dubbed "Stalin Towers" for Moscow; seven of these were eventually built. The rest of Europe also slowly began to permit skyscrapers, starting with Madrid, in Spain, during the 1950s. Finally, skyscrapers also began to appear in Africa, the Middle East and Oceania (mainly Australia) from the late 1950s and early 1960s.

Still today no city in the world has more completed individual free-standing buildings over 492 ft. (150 m) than New York City.^[3]. Hong Kong comes in with the most in the entire world^[4], if one counts individually the multiple towers that rise from a common podium (as Emporis does), in buildings that rise several stories as a single structure before splitting into two or more columns of floors. The number of skyscrapers in Hong Kong will continue to increase, due to a prolonged highrise building boom, because of high demand for office and housing space in the area. A new building complex in Kowloon contains several mixed-use towers (hotel-shops-residential) and one of them will be 118 stories tall.

Chicago's skyline was not allowed to grow until the height limits were relaxed in 1960; over the next fifteen years many towers were built, including the massive 442-meter (1,451-foot) Sears Tower,^[5] leading to its current number of buildings over 492 ft. Chicago is currently undergoing an epic construction boom that will greatly add to the city's skyline. Since 2000, at least 40 buildings at a minimum of 50 stories high have been built.^[6][7] The Chicago Spire, Trump International Hotel and Tower (Chicago), Waterview Tower, Mandarin Oriental Tower, 29-39 South LaSalle, Park Michigan, and Aqua are some of the more notable projects currently underway in the city that invented the skyscraper. Chicago, Hong Kong, and New York City, otherwise known as the "the big three," are recognized in most architectural circles as having the most compelling skylines in the world. Other large cities that are currently experiencing major building booms in skyscrapers include Shanghai in China and Dubai in the United Arab Emirates.

Today, skyscrapers are an increasingly common sight where land is scarce, as in the centres of big cities, because of the high ratio of rentable floor space per area of land. Skyscrapers, like temples and palaces in the past, are considered the symbols of a city's economic power.

History of tallest skyscrapers

At the beginning of the 20th century, New York City was a center for the Beaux-Arts architecutural movement, attracting the talents of such great architects like Stanford White and Carrere and Hastings. As better construction and engineering technology become available as the century progressed, New York became the focal point of the competition for the tallest building in the world. The city's striking skyline has been composed of numerous and varied skyscrapers, many of which are icons of 20th century architecture:

• The Flatiron Building, standing 285 ft (87 m) high, was one of the tallest buildings in the city upon its completion in 1902, made possible by its steel skeleton. It was one of the first buildings designed with a steel framework, and to achieve this height with other construction methods of that time would have been very difficult.

• The Woolworth Building, a neo-Gothic "Cathedral of Commerce" overlooking City Hall, was designed by Cass Gilbert. At 792 feet (241 m), it became the world's tallest building upon its completion in 1913, an honor it retained until 1930, when it was overtaken by 40 Wall Street.

• That same year, the Chrysler Building took the lead as the tallest building in the world, scraping the sky at 1,046 feet (319 m). More impressive than its height is the building's design, by William Van Alen. An art deco masterpiece with an exterior crafted of brick, the Chrysler Building continues to be a favorite of New Yorkers to this day.

• The Empire State Building, the first building to have more than 100 floors (it has 102), was completed the following year. It was designed by Shreve, Lamb and Harmon in the contemporary Art Deco style. The tower takes its name from the nickname of New York State. Upon its completion in 1931, it took the top spot as tallest building, and at 1,472 feet (448 m) to the very top of the antenna, towered above all other buildings until 1973.

• When the World Trade Center towers were completed in 1973 many felt them to be sterile monstrosities, even though they were the world's tallest buildings at that time. But most New Yorkers became fond of "The Twin Towers", and after the initial horror for the loss of life in the September 11, 2001 terrorist attacks there came great sadness for the loss of the buildings. The Empire State Building is again the tallest building in New York City.

Momentum in setting records passed from the Unites States to other nations in 1997 with the opening of the Petronas Twin Towers in Kuala Lumpur, Malaysia. The record for world's tallest building remained in Asia with the opening of Taipei 101 in Taipei, Taiwan, in 2004. A number of architectural records will likely reside in the Middle East in 2008 or 2009 with the opening of the Burj Dubai in Dubai, UAE.

With this geographical transition a change can be seen in the approach to skyscraper design. For much of the twentieth century large buildings such as the Sears Tower and World Trade Center (New York) took the form of simple geometrical shapes. They were designed as large boxes. This reflected the "international style" or modernist philosophy shaped by Bauhaus architects early in the century. By the 1990s skyscraper design began to exhibit postmodernist influences. The newest record setters, though modern, incorporate traditional architectural features associated with the part of the world where they stand. Taipei 101 and the Petronas Towers recall the traditions of Asian pagoda architecture even as the Burj Dubai incorporates motifs from traditional Arab art. The result in each case is a building that does not look equally at home in any skyline in any city in the world, but a building that reflects its own continent and culture.

For current rankings of skyscrapers by height, see List of skyscrapers.

The following list measures height of the roof. The more common gauge is the highest architectural detail; such ranking would have included Petronas Towers, built in 1998. See list of skyscrapers for details.

Built	Building	City	Country	Roof	Floors	Pinnacle	Current status
1873	Equitable Life Building	New York	U.S.	142 ft	43 m	8			Demolished
1889	Auditorium Building	Chicago	U.S.	269 ft	82 m	17	349 ft	106 m	Standing
1890	New York World Building	New York City	U.S.	309 ft	94 m	20	349 ft	106 m	Demolished
1894	Manhattan Life Insurance Building	New York City	U.S.	348 ft	106 m	18			Demolished
1899	Park Row Building	New York City	U.S.	391 ft	119 m	30			Standing
1901	Philadelphia City Hall	Philadelphia	U.S.			9	548 ft	167 m	Standing
1908	Singer Building	New York City	U.S.	612 ft	187 m	47			Demolished
1909	Met Life Tower	New York City	U.S.	700 ft	213 m	50			Standing
1913	Woolworth Building	New York City	U.S.	792 ft	241 m	57			Standing
1930	40 Wall Street	New York City	U.S.			70	927 ft	283 m	Standing
1930	Chrysler Building	New York City	U.S.	925 ft	282 m	77	1,046 ft	319 m	Standing
1931	Empire State Building	New York City	U.S.	1,250 ft	381 m	102	1,472 ft	449 m	Standing
1972	World Trade Center (North tower)	New York City	U.S.	1,368 ft	417 m	110	1,732 ft	528 m	Demolished
1974	Sears Tower	Chicago	U.S.	1,451 ft	442 m	108	1,729 ft	527 m	Standing
1998	Petronas Towers	Kuala Lumpur	Malaysia	1,322 ft	403 m	88	1,483 ft	452 m	Standing
2003	Taipei 101	Taipei City	Taiwan	1,474 ft	448 m	101	1,671 ft	509 m	Standing

Source: emporis.com

Future

The following skyscrapers are either proposed, approved or to be completed in the near future:

• Construction of the Burj Dubai is taking place in Dubai. Its exact future height is kept secret, but it is expected to become at least  m ( ft) high, making it the tallest building in the world. The Burj Dubai is due to be completed in June 2009.

• Standing at  m ( ft) and scheduled to be completed in 2008, the Shanghai World Financial Center is a mixed used skyscraper; consisting of office space, hotel rooms and shopping zones at ground level. It will surpass Jin Mao Tower and will be the tallest skyscraper in Shanghai and in main land China.

• Plans for a  m ( ft). skyscraper in Boston have been confirmed^[8], to be called Trans National Place. Construction is tentatively scheduled to begin in 2008 and be completed in 2011. If completed, it would be the tallest building in Boston and New England.

Quotations

"A chair is a very difficult object. A skyscraper is almost easier. That is why Chippendale is famous."

—Ludwig Mies van der Rohe

"What is the chief characteristic of the tall office building? It is lofty. It must be tall. The force and power of altitude must be in it, the glory and pride of exaltation must be in it. It must be every inch a proud and soaring thing, rising in sheer exaltation that from bottom to top it is a unit without a single dissenting line."

—Louis Sullivan's The Tall Office Building Artistically Considered (1896)

"A skyscraper is a boast in glass and steel."

—Mason Cooley

"The skyscraper establishes the block, the block creates the street, the street offers itself to man."

—Roland Barthes

"Manhattan has no choice but the skyward extrusion of the Grid itself; only the Skyscraper offers business the wide-open spaces of a man-made Wild West, a frontier in the sky."

—Rem Koolhaas

"As the twentieth century fades, North America is ceding skyscraper supremacy to Asia."

—Emily Mitchell in Time Magazine, (1994)

"The tall building ought to participate in the city as both a facade, connecting the walls of the street, and as an object against the sky."

—William Pedersen in Process Architecture, 1986

"Architecture is the alphabet of giants; it is the largest set of symbols ever made to meet the eyes of men. A tower stands up like a sort of simplified statue, of much more than heroic size."

—Gilbert Keith Chesterton

Skyline Imagery

It has been suggested that the skyline images in this section be transferred to Skyline. (Discuss)

With tall, distinctive skyscrapers, these skyline images show how skyscrapers are able to affect, define and transform cities into skylines.

Panorama view of the Jakarta Skyline

See also

• List of tallest buildings in the world
• Emporis Skyscraper Award
• Skyline
• Skyscrapers in film
• Skyscraper design and construction
• Supertall

References

1. ^ Data Standards: Real Estate A high-rise building is defined as a building 35 meters or greater in height
2. ^ Penza State University of Architecture and Construction; Before The Workshop (1) Tower
3. ^ List of Tallest skyscrapers in New York City
4. ^ List of Tallest skyscrapers in Hong Kong
5. ^ List of Tallest skyscrapers in Chicago
6. ^ Chicago Building Boom
7. ^ SkyscraperPage.com - Every building above 12 stories
8. ^ Trans National Place, Boston from Emporis.com

• Skyscrapers: Form and Function, by David Bennett, Simon & Schuster, 1995.

External links

Wikimedia Commons has media related to:

• Historical photos of skyscrapers in New York City
• Skyscraper Museum
• SkyscraperPage - Technical information and diagrams
• SkyScrapers.org - High Resolution skyscraper illustrations; structural facts & research
• / Skyscrapers at the Open Directory Project
• Skyscraper 1880s "skyscraper" citations from word researcher Barry Popik.

Tallest buildings and structures in the world (category)
Buildings and structures	by country Australia · Austria · Canada · People's Republic of China · France · Hungary · India · Ireland · Japan · Middle East · Portugal · former Soviet Union · United Kingdom
Buildings	100+ floors · Churches · History of tallest skyscrapers Europe · European Union · Brazil · Canada · Czech Republic · Finland · Germany · Hong Kong · India · Israel · Lithuania · Mexico · Pakistan · Poland · Singapore · Sri Lanka · Turkey · United Arab Emirates · United States
Structures	Towers · Chimneys Belgium · Bulgaria · Commonwealth of Nations · Czech Republic · Denmark · Europe · Finland · Germany · Hungary · Iceland · Japan · Luxemburg · Netherlands · Norway · Poland · Slovakia · Spain · Sweden · Switzerland · United States · Former Yugoslavia
Relevant Architecture	Additionally guyed tower · Architectural structure · Antenna height considerations · Air traffic obstacle · Construction · Height restriction laws · Oil platform · Partially guyed tower · Supertall
Lists	List of buildings · List of largest buildings in the world · List of world's largest domes

be-x-old:Небасяг

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Dansk (Danish)
n. - skyskraber

Nederlands (Dutch)
wolkenkrabber

Français (French)
n. - gratte-ciel

Deutsch (German)
n. - Wolkenkratzer

Ελληνική (Greek)
n. - ουρανοξύστης

Italiano (Italian)
grattacielo

Português (Portuguese)
n. - arranha-céu (m)

Русский (Russian)
небоскреб, высотный дом

Español (Spanish)
n. - rascacielos

Svenska (Swedish)
n. - skyskrapa

中文（简体） (Chinese (Simplified))
摩天楼, 超高层大楼, 特别高的东西

中文（繁體） (Chinese (Traditional))
n. - 摩天樓, 超高層大樓, 特別高的東西

한국어 (Korean)
n. - 마천루, (쾌속 범선의) 맨 위의 돛, (여러 층의) 대형 샌드위치

日本語 (Japanese)
n. - 超高層ビル, 摩天楼, 高層建築物

العربيه (Arabic)
‏(الاسم) ناطحه سحاب‏

עברית (Hebrew)
n. - ‮גורד שחקים‬

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