Askyscraper is a tall building with many habitable floors. Most modern sources define skyscrapers as being at least 100 metres (330 ft)[1] or 150 metres (490 ft)[2] in height, though there is no universally accepted definition, other than being very tallhigh-rise buildings. Skyscrapers may host offices, hotels, residential spaces, and retail spaces. Skyscrapers are a common feature of large cities, often due to a high demand for space and limited availability of land.
One common feature of skyscrapers is having asteel frame that supportscurtain walls. These curtain walls either bear on the framework below or are suspended from the framework above, rather than resting onload-bearing walls of conventional construction. Some early skyscrapers have a steel frame that enables the construction of load-bearing walls taller than those made ofreinforced concrete. Modern skyscraper walls are notload-bearing, and most skyscrapers are characterized by large surface areas of windows made possible by steel frames and curtain walls. However, skyscrapers can have curtain walls that mimic conventional walls with a small surface area of windows. Modern skyscrapers often have atubular structure, and are designed to act like a hollowcylinder to resist wind,seismic, and other lateral loads. To appear more slender, allow less wind exposure and transmit more daylight to the ground, many skyscrapers have a design withsetbacks, which in some cases is also structurally required.
Skyscrapers first appeared in the United States at the end of the 19th century, especially in the cities ofChicago andNew York City. Following a building boom across thewestern world in the early 20th century, skyscraper development was halted in the 1930s by theGreat Depression, and did not resume until the 1950s. A skyscraper boom in thedowntowns of many American cities took place during the 1960s to 1980s. Towards the second half of the 20th century, skyscrapers began to be built more frequently outside the United States, particularly inEast Asia andSoutheast Asia during the 1990s. China has since overtaken the United States as the country with the most skyscrapers. Skyscrapers are an increasingly global phenomenon, and can be found in over 70 countries.[3]
There are over 7 thousand skyscrapers over 150 m (492 ft) in height worldwide, most of which were built in the 21st century.[4] Over three-quarters of skyscrapers taller than 150 m (492 ft) are located in Asia. Eighteen cities in the world have more than 100 skyscrapers that are taller than 150 m (492 ft), most recentlyToronto and Singapore in 2025. Thecity with the most skyscrapers in the world isHong Kong, with 569 skyscrapers, followed byShenzhen in China with 444,New York City with 317, andDubai in the United Arab Emirates with 270. Dubai is home to thetallest skyscraper in the world, theBurj Khalifa.
By some measures, what came to be known as a "skyscraper" first appeared inChicago with the 1885 completion of the world's first largely steel-frame structure, theHome Insurance Building. It was demolished in 1931.
The term "skyscraper" was first applied to buildings of steel-framed construction of at least 10stories in the late 19th century, a result of public amazement at the tall buildings being built in major American cities likeNew York City,Philadelphia,Boston,Chicago,Detroit, andSt. Louis.[5][6]
The first steel-frame skyscraper was theHome Insurance Building, originally 10 stories with a height of 42 m or 138 ft, in Chicago in 1885; two additional stories were added.[7] Some point to Philadelphia's 10-storyJayne Building (1849–50) as a proto-skyscraper,[8] or to New York's seven-floorEquitable Life Building, built in 1870. Steel skeleton construction has allowed for today'ssupertall skyscrapers now being built worldwide.[9] The nomination of one structure versus another being the first skyscraper, and why, depends on what factors are stressed.[10]
The structural definition of the wordskyscraper 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-bearingmasonry, which passed their practical limit in 1891 with Chicago'sMonadnock Building.
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'sThe Tall Office Building Artistically Considered (1896)
Somestructural engineers define a high-rise as any vertical construction for which wind is a more significantload factor thanearthquake or weight. Note that this criterion fits not only high-rises but some other tall structures, such astowers.
Different organizations from the United States and Europe define skyscrapers as buildings at least 150 m (490 ft) in height or taller,[11][6][12] with "supertall" skyscrapers for buildings higher than 300 m (984 ft) and "megatall" skyscrapers for those taller than 600 m (1,969 ft).[13]
Thetallest structure in ancient times was the 146 m (479 ft)Great Pyramid of Giza inancient Egypt, built in the 26th century BC. It was not surpassed in height for thousands of years, the 160 m (520 ft)Lincoln Cathedral having exceeded it in 1311–1549, before its central spire collapsed.[14] The latter in turn was not surpassed until the 555-foot (169 m)Washington Monument in 1884, which was surpased by theEiffel Tower in 1889, the first ever supertall structure. However, being uninhabited, none of these structures actually comply with the modern definition of a skyscraper,[citation needed] only in 1930 theChrysler Building surpassed the Eiffel Tower by pinnacle height, becoming the first skyscraper being the tallest structure built until then and the first supertall skyscraper by pinnacle height, only to be surpassed a year later in every regard by theEmpire State Building as the first supertall skyscraper also by roof height.
High-rise apartments flourished inclassical antiquity.Ancient Romaninsulae inimperial cities reached 10 and more stories.[15] Beginning withAugustus (r. 30 BC-14 AD), severalemperors attempted to establish limits of 20–25 m (66–82 ft) for multi-stories buildings, but were met with only limited success.[16][17] Lower floors were typically occupied by shops or wealthy families, with the upper rented to the lower classes.[15] SurvivingOxyrhynchus Papyri indicate that seven-stories buildings existed inprovincial towns such as in 3rd century ADHermopolis inRoman Egypt.[18]
The skylines of many importantmedieval cities had large numbers of high-rise urban towers, built by the wealthy for defense and status. The residentialTowers of 12th centuryBologna numbered between 80 and 100 at a time, the tallest of which is the 97.2 m (319 ft) high Asinelli Tower. AFlorentine law of 1251 decreed that all urban buildings be immediately reduced to less than 26 m (85 ft).[19] Even medium-sized towns of the era are known to have proliferations of towers, such as the 72 towers that ranged up to 51 m (167 ft) height inSan Gimignano.[19]
Themedieval Egyptian city ofFustat housed many high-rise residential buildings, whichAl-Muqaddasi in the 10th century described as resemblingminarets.Nasir Khusraw in the early 11th century described some of them rising up to 14 stories, withroof gardens on the top floor complete with ox-drawnwater wheels for irrigating them.[20]Cairo in the 16th century had high-riseapartment buildings where the two lower floors were for commercial and storage purposes and the multiple stories above them wererented out totenants.[21] An early example of a city consisting entirely of high-rise housing is the 16th-century city ofShibam in Yemen. Shibam was made up of over 500 tower houses,[22] each one rising 5 to 11 stories high,[23] with each floor being anapartment occupied by a single family. The city was built in this way in order to protect it fromBedouin attacks.[22] Shibam still has the tallestmudbrick buildings in the world, with many of them over 30 m (98 ft) high.[24]
An early modern example of high-rise housing was in 17th-centuryEdinburgh, Scotland, where a defensive city wall defined the boundaries of the city. Due to the restricted land area available 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, although only partially iron framed, isThe Flaxmill inShrewsbury, England. Built in 1797, it is seen as the "grandfather of skyscrapers", since its fireproof combination of cast iron columns and cast iron beams developed into the modern steel frame that made modern skyscrapers possible. In 2013 funding was confirmed to convert the derelict building into offices.[25]
In 1857,Elisha Otis introduced thesafety elevator at theE. V. Haughwout Building in New York City, allowing convenient and safe transport to buildings' upper floors. Otis later introduced the first commercial passenger elevators to theEquitable Life Building in 1870, considered by some architectural historians to be the first skyscraper. Another crucial development was the use of a steel frame instead of stone or brick, otherwise the walls on the lower floors on a tall building would be too thick to be practical. An early development in this area wasOriel Chambers inLiverpool, England, built in 1864. It was only five floors high.[26][27] TheRoyal Academy of Arts states, "critics at the time were horrified by its 'large agglomerations of protruding plate glass bubbles'. In fact, it was a precursor to Modernist architecture, being the first building in the world to feature a metal-framed glasscurtain wall, a design element which creates light, airy interiors and has since been used the world over as a defining feature of skyscrapers".[28]
Further developments led to what many individuals and organizations consider the world's first skyscraper, the ten-storyHome Insurance Building in Chicago, built from 1884 to 1885.[29] While its original height of 42.1 m (138 ft) does not qualify as a skyscraper today, it was record setting for the day. The building of tall buildings in the 1880s gave the skyscraper its first architectural movement, broadly termed theChicago School, which developed what has been called the Commercial Style.[30]
The architect, MajorWilliam Le Baron Jenney, created a 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. This was then draped with a stone curtain for aesthetic purposes. This development led to the "Chicago skeleton" form of construction. In addition to the steel frame, the Home Insurance Building also utilized fireproofing, elevators, and electrical wiring, key elements in most skyscrapers today.[31]
Most early skyscrapers emerged in the land-strapped areas of New York City and Chicago toward the end of the 19th century. A land boom inMelbourne, Australia between 1888 and 1891 spurred the creation of a significant number of early skyscrapers, though none of these were steel reinforced and few remain today. Height limits and fire restrictions were later introduced. In the late 1800s,London builders found building heights limited due to issues with existing buildings. High-rise development in London is restricted at certain sites if it would obstructprotected views ofSt Paul's Cathedral and other historic buildings.[33] This policy, 'St Paul's Heights', has officially been in operation since 1927.[34]
Concerns aboutaesthetics and fire safety had likewise hampered the development of skyscrapers across continental Europe for the first half of the 20th century. By 1940, there were around 100 high-rise buildings in Europe (List of early skyscrapers). Some examples of these are the 43 m (141 ft) tall 1898Witte Huis(White House) inRotterdam; the 51.5 m (169 ft) tallPAST Building (1906–1908) inWarsaw; theRoyal Liver Building in Liverpool, completed in 1911 and 90 m (300 ft) high;[35] the 57 m (187 ft) tall 1924Marx House inDüsseldorf, the 65 m (213 ft) tallBorsigturm inBerlin, built in 1924, the 65 m (213 ft) tallHansahochhaus inCologne, Germany, built in 1925; the 61 m (200 ft)Kungstornen(Kings' Towers) inStockholm, Sweden, which were built 1924–25;[36] the 77 m (253 ft)Ullsteinhaus in Berlin, Germany, built in 1927; the 89 m (292 ft)Edificio Telefónica inMadrid, Spain, built in 1929; the 87.5 m (287 ft)Boerentoren in Antwerp, Belgium, built in 1932; the 66 m (217 ft)Prudential Building inWarsaw, Poland, built in 1934; and the 108 m (354 ft)Torre Piacentini inGenoa, Italy, built in 1940.
After an early competition between New York City and Chicago for the world's tallest building, New York took the lead by 1895 with the completion of the 103 m (338 ft) tallAmerican Surety Building, leaving New York with the title of the world's tallest building for many years. America by far produced the most skyscrapers in this period.
Skyscrapers and buildings in (Abu Dhabi, Middle East)
Modern skyscrapers are built withsteel orreinforced concrete frameworks andcurtain walls ofglass orpolished stone. They use mechanical equipment such aswater pumps andelevators. Since the 1960s, according to the CTBUH (Council on Tall Buildings and Urban Habitat) the skyscraper has been reoriented away from a symbol forNorth American corporate power to instead communicate a city or nation's place in the world.[37]
From the 1930s onward, skyscrapers began to appear in various cities inEast andSoutheast Asia as well as inLatin America. Finally, they also began to be constructed in cities in Africa, the Middle East,South Asia, and Oceania from the late 1950s.
Skyscraper projects after World War II typically rejected the classical designs of theearly skyscrapers, instead embracing the uniforminternational style; many older skyscrapers were redesigned to suit contemporary tastes or even demolished—such as New York'sSinger Building, once the world's tallest skyscraper.
German-American architectLudwig Mies van der Rohe became one of the world's most renowned architects in the second half of the 20th century. He conceived the glass façade skyscraper[38] and, along with NorwegianFred Severud,[39] designed theSeagram Building in 1958, a skyscraper that is often regarded as the pinnacle of modernist high-rise architecture.[40]
Skyscraper construction surged throughout the 1960s. The impetus behind the upswing was a series of transformative innovations[41] which made it possible for people to live and work in "cities in the sky".[42]
In the early 1960sBangladeshi-American structural engineerFazlur Rahman Khan, considered the "father oftubular designs" for high-rises,[44] discovered that the dominating rigidsteel frame structure was not the only system apt for tall buildings, marking a new era of skyscraper construction in terms of multiplestructural systems.[45] His central innovation inskyscraper design and construction was the concept of the"tube" structural system, including the "framed tube", "trussed tube", and "bundled tube".[46] His "tube concept", using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design.[47] These systems allow greater economic efficiency,[48] and also allow skyscrapers to take on various shapes, no longer needing to be rectangular and box-shaped.[49] The first building to employ the tube structure was theChestnut De-Witt apartment building,[41] considered to be a major development in modern architecture.[41] These new designs opened an economic door for contractors, engineers, architects, and investors, providing vast amounts of real estate space on minimal plots of land.[42] Over the next fifteen years, many towers were built by Fazlur Rahman Khan and the "Second Chicago School",[50] including the hundred-storyJohn Hancock Center and the massive 442 m (1,450 ft)Willis Tower.[51] Other pioneers of this field includeHal Iyengar,William LeMessurier, andMinoru Yamasaki, the architect of theWorld Trade Center.
Many buildings designed in the 1970s lacked a particular style and recalled ornamentation from earlier buildings designed before the 1950s. These design plans ignored the environment and loaded structures with decorative elements and extravagant finishes.[52] This approach to design was opposed by Fazlur Khan and he considered the designs to be whimsical rather than rational. Moreover, he considered the work to be a waste of precious natural resources.[53] Khan's work promotedstructures integrated with architecture and the least use of material resulting in the smallest impact on the environment.[54] The next era of skyscrapers will focus on the environment including performance of structures, types of material, construction practices, absolute minimal use of materials/natural resources, embodied energy within the structures, and more importantly, a holistically integrated building systems approach.[52]
Modern building practices regarding supertall structures have led to the study of "vanity height".[55][56] Vanity height, according to the CTBUH, is the distance between the highest floor and its architectural top (excluding antennae, flagpole or other functional extensions). Vanity height first appeared in New York City skyscrapers as early as the 1920s and 1930s but supertall buildings have relied on such uninhabitable extensions for on average 30% of their height, raising potential definitional and sustainability issues.[57][58][59] The current era of skyscrapers focuses onsustainability, its built and natural environments, including the performance of structures, types of materials, construction practices, absolute minimal use of materials and natural resources, energy within the structure, and a holistically integrated building systems approach.LEED is a currentgreen building standard.[60]
3 September is the global commemorative day for skyscrapers, called "Skyscraper Day".[62]
New York City developers 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 318.9 m (1,046 ft)Chrysler Building in 1930 and the 443.2 m (1,454 ft)Empire State Building in 1931, the world's tallest building for forty years. The first completed 417 m (1,368 ft) tallWorld Trade Center tower became the world's tallest building in 1972. However, it was overtaken by the Sears Tower (nowWillis Tower) in Chicago within two years. The 442 m (1,450 ft) tall Sears Tower stood as the world's tallest building for 24 years, from 1974 until 1998, until it was edged out by 452 m (1,483 ft)Petronas Twin Towers in Kuala Lumpur, which held the title for six years.
The Sky Garden in London's20 Fenchurch Street is an example of where top floors are used as restaurants or viewing areas, and in this case, both.Contemporary skyscrapers inShanghai
The design and construction of skyscrapers involves creating safe, habitable spaces in very tall buildings. The buildings must support their weight, resist wind and earthquakes, and protect occupants from fire. Yet they must also be conveniently accessible, even on the upper floors, and provide utilities and a comfortable climate for the occupants. The problems posed in skyscraper design are considered among the most complex encountered given the balances required betweeneconomics,engineering, andconstruction management.
One common feature of skyscrapers is a steel framework from which curtain walls are suspended, rather than load-bearing walls of conventional construction. Most skyscrapers have a steel frame that enables them to be built taller than typical load-bearing walls of reinforced concrete. Skyscrapers usually have a particularly small surface area of what are conventionally thought of as walls. Because the walls are not load-bearing most skyscrapers are characterized by surface areas of windows made possible by the concept of steel frame and curtain wall. However, skyscrapers can also have curtain walls that mimic conventional walls and have a small surface area of windows.
The concept of a skyscraper is a product of theindustrialized age, made possible by cheapfossil fuel derived energy and industrially refined raw materials such assteel andconcrete. The construction of skyscrapers was enabled bysteel frame construction that surpassedbrick and mortar construction starting at the end of the 19th century and finally surpassing it in the 20th century together withreinforced concrete construction as the price of steel decreased and labor costs increased.
The steel frames become inefficient and uneconomic for supertall buildings as usable floor space is reduced for progressively larger supporting columns.[63] Since about 1960, tubular designs have been used for high rises. This reduces the usage of material (more efficient in economic terms –Willis Tower uses a third less steel than the Empire State Building) yet allows greater height. It allows fewer interior columns, and so creates more usable floor space. It further enables buildings to take on various shapes.
Elevators are characteristic to skyscrapers. In 1852 Elisha Otis introduced the safety elevator, allowing convenient and safe passenger movement to upper floors. Today major manufacturers of elevators includeOtis,ThyssenKrupp,Schindler, andKONE.
Advances in construction techniques have allowed skyscrapers to narrow in width, while increasing in height. Some of these new techniques includemass dampers to reduce vibrations and swaying, and gaps to allow air to pass through, reducing wind shear.[64]
A view of the interior structural design can be seen in this residential skyscraper that was constructed inFlorida, theJade Signature.
Good structural design is important in most building design, but particularly for skyscrapers since even a small chance of catastrophic failure is unacceptable given the tremendous damage such failure would cause. This presents a paradox tocivil engineers: the only way to assure a lack of failure is to test for all modes of failure, in both the laboratory and the real world. But the only way to know of all modes of failure is to learn from previous failures. Thus, no engineer can be absolutely sure that a given structure will resist all loadings that could cause failure; instead, one can only have large enough margins of safety such that a failure is acceptably unlikely. When buildings do fail, engineers question whether the failure was due to some lack of foresight or due to some unknown factor.
The load a skyscraper experiences is largely from the force of the building material itself. In most building designs, the weight of the structure is much larger than the weight of the material that it will support beyond its own weight. In technical terms, thedead load, the load of the structure, is larger than thelive load, the weight of things in the structure (people, furniture, vehicles, etc.). As such, the amount of structural material required within the lower levels of a skyscraper will be much larger than the material required within higher levels. This is not always visually apparent. TheEmpire State Building'ssetbacks are actually a result of the building code at the time (1916 Zoning Resolution), and were not structurally required. On the other hand,John Hancock Center's shape is uniquely the result of how it supports loads. Vertical supports can come in several types, among which the most common for skyscrapers can be categorized as steel frames, concrete cores, tube within tube design, and shear walls.
The wind loading on a skyscraper is also considerable. In fact, the lateral wind load imposed on supertall structures is generally the governing factor in the structural design. Wind pressure increases with height, so for very tall buildings, the loads associated with wind are larger than dead or live loads.
Other vertical and horizontal loading factors come from varied, unpredictable sources, such as earthquakes.
By 1895,steel had replacedcast iron as skyscrapers' structural material. Its malleability allowed it to be formed into a variety of shapes, and it could be riveted, ensuring strong connections.[65] The simplicity of a steel frame eliminated the inefficient part of a shear wall, the central portion, and consolidated support members in a much stronger fashion by allowing both horizontal and vertical supports throughout. Among steel's drawbacks is that as more material must be supported as height increases, the distance between supporting members must decrease, which in turn increases the amount of material that must be supported. This becomes inefficient and uneconomic for buildings above 40 stories tall as usable floor spaces are reduced for supporting column and due to more usage of steel.[63]
TheWillis Tower in Chicago visibly expresses the bundled tube frame. Tube frame variations are commonly used in tall modern skyscapers.
A new structural system of framed tubes was developed byFazlur Rahman Khan in 1963. The framed tube structure is defined as "a three dimensional space structure composed of three, four, or possibly more frames, braced frames, or shear walls, joined at or near their edges to form a vertical tube-like structural system capable of resisting lateral forces in any direction by cantilevering from the foundation".[66][67] Closely spaced interconnected exterior columns form the tube. Horizontal loads (primarily wind) are supported by the structure as a whole. Framed tubes allow fewer interior columns, and so create more usable floor space, and about half the exterior surface is available for windows. Where larger openings like garage doors are required, the tube frame must be interrupted, with transfer girders used to maintain structural integrity. Tube structures cut down costs, at the same time allowing buildings to reach greater heights. Concrete tube-frame construction[46] was first used in theDeWitt-Chestnut Apartment Building, completed inChicago in 1963,[68] and soon after in theJohn Hancock Center andWorld Trade Center.
Changes of structure with height; thetubular systems are fundamental for supertall buildings.
Khan pioneered several other variations of the tube structure design. One of these was the concept ofX-bracing, or thetrussed tube, first employed for theJohn Hancock Center. This concept reduced the lateral load on the building by transferring the load into the exterior columns. This allows for a reduced need for interior columns thus creating more floor space. This concept can be seen in the John Hancock Center, designed in 1965 and completed in 1969. One of the most famous buildings of thestructural expressionist style, the skyscraper's distinctive X-bracing exterior is actually a hint that the structure's skin is indeed part of its 'tubular system'. This idea is one of the architectural techniques the building used to climb to record heights (the tubular system is essentially the spine that helps the building stand upright during wind andearthquake loads). This X-bracing allows for both higher performance from tall structures and the ability to open up the inside floorplan (and usable floor space) if the architect desires.
Bundled tube:An important variation on the tube frame is thebundled tube, which uses several interconnected tube frames. TheWillis Tower in Chicago used this design, employing nine tubes of varying height to achieve its distinct appearance. The bundled tube structure meant that "buildings no longer need be boxlike in appearance: they could become sculpture."[49]
Tube in tube:Tube-in-tube system takes advantage of core shear wall tubes in addition to exterior tubes. The inner tube and outer tube work together to resist gravity loads and lateral loads and to provide additional rigidity to the structure to prevent significant deflections at the top. This design was first used inOne Shell Plaza.[72] Later buildings to use this structural system include thePetronas Towers.[73]
Outrigger and belt truss:The outrigger and belt truss system is a lateral load resisting system in which the tube structure is connected to the central core wall with very stiff outriggers and belt trusses at one or more levels.[74]BHP House was the first building to use this structural system followed by the First Wisconsin Center, since renamedU.S. Bank Center, in Milwaukee. The center rises 601 feet, with three belt trusses at the bottom, middle and top of the building. The exposed belt trusses serve aesthetic and structural purposes.[75] Later buildings to use this includeShanghai World Financial Center.[74]
Concrete tube structures:The last major buildings engineered by Khan were theOne Magnificent Mile andOnterie Center in Chicago, which employed his bundled tube and trussed tube system designs respectively. In contrast to his earlier buildings, which were mainly steel, his last two buildings were concrete. His earlierDeWitt-Chestnut Apartments building, built in 1963 in Chicago, was also a concrete building with a tube structure.[46]Trump Tower in New York City is also another example that adapted this system.[76]
Khan developed the shear wall frame interaction system for mid high-rise buildings. This structural system uses combinations of shear walls and frames designed to resist lateral forces.[77] The first building to use this structural system was the 35-stories Brunswick Building.[75] The Brunswick building (today known as the "Cook County Administration Building") was completed in 1965 and became the tallest reinforced concrete structure of its time. The structural system of Brunswick Building consists of a concrete shear wall core surrounded by an outer concrete frame of columns and spandrels.[78] Apartment buildings up to 70 stories high have successfully used this concept.[79]
The invention of theelevator was a precondition for the invention of skyscrapers, given that most people would not (or could not) climb more than a few flights of stairs at a time. The elevators in a skyscraper are not simply a necessary utility, like running water and electricity, but are in fact closely related to the design of the whole structure: a taller building requires more elevators to service the additional floors, but the elevator shafts consume valuable floor space. If the service core, which contains the elevator shafts, becomes too big, it can reduce the profitability of the building. Architects must therefore balance the value gained by adding height against the value lost to the expanding service core.[80]
Sky lobby atCentral Plaza inHong Kong which has clear signage of the floors served by the different elevators.
Many tall buildings use elevators in a non-standard configuration to reduce their footprint. Buildings such as the formerWorld Trade Center Towers and Chicago'sJohn Hancock Center usesky lobbies, where express elevators take passengers to upper floors which serve as the base for local elevators. This allows architects and engineers to place elevator shafts on top of each other, saving space. Sky lobbies and express elevators take up a significant amount of space, however, and add to the amount of time spent commuting between floors.
Other buildings, such as thePetronas Towers, usedouble-deck elevators, allowing more people to fit in a single elevator, and reaching two floors at every stop. It is possible to use even more than two levels on an elevator, although this has never been done. The main problem with double-deck elevators is that they cause everyone in the elevator to stop when only person on one level needs to get off at a given floor.
Hong Kong's high land prices and geographic limitations justify the construction of skyscrapers[82]
Skyscrapers are usually situated incity centres where the price of land is high. Constructing a skyscraper becomes justified if the price of land is so high that it makeseconomic sense to build upward as to minimize the cost of the land per the total floor area of a building. Thus the construction of skyscrapers is dictated by economics and results in skyscrapers in a certain part of a large city unless abuilding code restricts the height of buildings.
Skyscrapers are rarely seen in small cities and they are characteristic of large cities, because of the critical importance of high land prices for the construction of skyscrapers. Usually only office, commercial and hotel users can afford the rents in the city center and thus most tenants of skyscrapers are of these classes.
Today, skyscrapers are an increasingly common sight where land is expensive, as in the centres of big cities, because they provide such a high ratio of rentable floor space per unit area of land.
Another disadvantage of very high skyscrapers is the loss of usable floorspace, as many elevator shafts are needed to enable performant vertical travelling. This led to the introduction of express lifts andsky lobbies where transfer to slower distribution lifts can be done.
The Gherkin in London is an example of a modern environmentally friendly skyscraper.
Constructing a single skyscraper requires large quantities of materials like steel, concrete, and glass, and these materials represent significantembodied energy. Skyscrapers are thus material and energy intensive buildings.
Skyscrapers have considerable mass, requiring a stronger foundation than a shorter, lighter building. In construction, building materials must be lifted to the top of a skyscraper during construction, requiring more energy than would be necessary at lower heights. Furthermore, a skyscraper consumes much electricity becausepotable and non-potable water have to be pumped to the highest occupied floors, skyscrapers are usually designed to bemechanically ventilated, elevators are generally used instead of stairs, and electric lights are needed in rooms far from the windows and windowless spaces such as elevators, bathrooms and stairwells.
Skyscrapers can be artificially lit and the energy requirements can be covered byrenewable energy or other electricity generation with lowgreenhouse gas emissions. Heating and cooling of skyscrapers can be efficient, because of centralizedHVAC systems, heat radiation blockingwindows and small surface area of the building. There isLeadership in Energy and Environmental Design (LEED) certification for skyscrapers. For example, the Empire State Building received a gold Leadership in Energy and Environmental Design rating in September 2011 and the Empire State Building is the tallest LEED certified building in the United States,[83] proving that skyscrapers can be environmentally friendly.The Gherkin inLondon, the United Kingdom is another example of an environmentally friendly skyscraper.[84]
In the lower levels of a skyscraper a larger percentage of the building floor area must be devoted to the building structure and services than is required for lower buildings:
More structure – because it must be stronger to support more floors above
The elevator conundrum creates the need for more lift shafts—everyone comes in at the bottom and they all have to pass through the lower part of the building to get to the upper levels.
Building services – power and water enter the building from below and have to pass through the lower levels to get to the upper levels.
In low-rise structures, the support rooms (chillers,transformers,boilers,pumps andair handling units) can be put in basements or roof space—areas which have low rental value. There is, however, a limit to how far this plant can be located from the area it serves. The farther away it is the larger the risers for ducts and pipes from this plant to the floors they serve and the more floor area these risers take. In practice this means that in highrise buildings this plant is located on 'plant levels' at intervals up the building.
The building sector accounts for approximately 50% of greenhouse gas emissions, with operational energy accounting for 80-90% of building related energy use.[85] Operational energy use is affected by the magnitude of conduction between the interior and exterior, convection from infiltrating air, and radiation throughglazing. The extent to which these factors affect the operational energy vary depending on themicroclimate of the skyscraper, with increased wind speeds as the height of the skyscraper increases, and a decrease in thedry bulb temperature as the altitude increases.[85] For example, when moving from 1.5 meters to 284 meters, the dry bulb temperature decreased by 1.85 °C while the wind speeds increased from 2.46 meters per seconds to 7.75 meters per second, which led to a 2.4% decrease in summer cooling in reference to theFreedom Tower in New York City. However, for the same building it was found that the annual energy use intensity was 9.26% higher because of the lack of shading at high altitudes which increased the cooling loads for the remainder of the year while a combination of temperature, wind, shading, and the effects of reflections led to a combined 13.13% increase in annual energy use intensity.[86]
In a study performed by Leung and Ray in 2013, it was found that the averageenergy use intensity of a structure with between 0 and 9 floors was approximately 80 kBtu/ft/yr, while the energy use intensity of a structure with more than 50 floors was about 117 kBtu/ft/yr. The slight decrease in energy use intensity over 30-39 floors can be attributed to the fact that the increase in pressure within the heating, cooling, and water distribution systems levels out at a point between 40 and 49 floors and the energy savings due to the microclimate of higher floors are able to be seen.[87] There is a gap in data in which another study looking at the same information but for taller buildings is needed.
A portion of the operational energy increase in tall buildings is related to the usage of elevators because the distance traveled and the speed at which they travel increases as the height of the building increases. Between 5 and 25% of the total energy consumed in a tall building is from the use ofelevators. As the height of the building increases it is also more inefficient because of the presence of higher drag and friction losses.[88]
Theembodied energy associated with the construction of skyscrapers varies based on the materials used. Embodied energy is quantified per unit of material. Skyscrapers inherently have higher embodied energy than low-rise buildings due to the increase in material used as more floors are built. For all floor types except for steel-concrete floors, it was found that after 60 stories, there was a decrease in unit embodied energy but when considering all floors, there was exponential growth due to a double dependence on height. The first of which is the relationship between an increase in height leading to an increase in the quantity of materials used, and the second being the increase in height leading to an increase in size of elements to increase the structural capacity of the building. A careful choice in building materials can likely reduce the embodied energy without reducing the number of floors constructed within the bounds presented.[89]
Similar to embodied energy, theembodied carbon of a building is dependent on the materials chosen for its construction. Both methods of measuring the embodied carbon show that there is a point where the embodied carbon is lowest before increasing again as the height increases. For the total embodied carbon it is dependent on the structure type, but is either around 40 stories, or approximately 60 stories. For the square meter of gross floor area, the lowest embodied carbon was found at either 40 stories, or approximately 70 stories.[90]
In urban areas, the configuration of buildings can lead to exacerbated wind patterns and an uneven dispersion ofpollutants. When the height of buildings surrounding a source ofair pollution is increased, the size and occurrence of both "dead-zones" and "hotspots" were increased in areas where there were almost no pollutants and high concentrations of pollutants, respectively. This progression shows how as the height of Building F increases, the dispersion of pollutants decreases, but the concentration within the building cluster increases. The variation ofvelocity fields can be affected by the construction of new buildings as well, rather than solely the increase in height.[91]
As urban centers continue to expand upward and outward, the present velocity fields will continue to trap polluted air close to the tall buildings within the city. Specifically within major cities, a majority of air pollution is derived from transportation, whether it be cars, trains, planes, or boats. Asurban sprawl continues and pollutants continue to be emitted, the air pollutants will continue to be trapped within these urban centers.[92] Different pollutants can be detrimental to human health in different ways. For example,particulate matter from vehicular exhaust and power generation can cause asthma, bronchitis, and cancer, whilenitrogen dioxide from motor engine combustion processes can cause neurological disfunction and asphyxiation.[93]
Shanghai Tower, the tallest and largest LEED Platinum certified building in the world since 2015.
Like with all other buildings, if special measures are taken to incorporatesustainable design methods early on in the design process, it is possible to obtain a green building rating, such as aLeadership in Energy and Environmental Design (LEED) certification. Anintegrated design approach is crucial in making sure that design decisions that positively impact the whole building are made at the beginning of the process. Because of the massive scale of skyscrapers, the decisions made by the design team must take all factors into account, including the buildings impact on the surrounding community, the effect of the building on the direction in which air and water move, and the impact of the construction process, must be taken into account. There are several design methods that could be employed in the construction of a skyscraper that would take advantage of the height of the building.[94]
The microclimates that exist as the height of the building increases can be taken advantage of to increase thenatural ventilation, decrease the cooling load, and increase daylighting. Natural ventilation can be increased by utilizing thestack effect, in which warm air moves upward and increases the movement of the air within the building. If utilizing the stack effect, buildings must take extra care to design for fire separation techniques, as the stack effect can also exacerbate the severity of a fire.[95] Skyscrapers are considered to be internally dominated buildings because of their size as well as the fact that a majority are used as some sort of office building with high cooling loads. Due to the microclimate created at the upper floors with the increased wind speed and the decreased dry bulb temperatures, the cooling load will naturally be reduced because of infiltration through the thermal envelope. By taking advantage of the naturally cooler temperatures at higher altitudes, skyscrapers can reduce their cooling loads passively. On the other side of this argument, is the lack of shading at higher altitudes by other buildings, so thesolar heat gain will be larger for higher floors than for floors at the lower end of the building. Special measures should be taken to shade upper floors from sunlight during the overheated period to ensure thermal comfort without increasing the cooling load.[87]
At the beginning of the 20th century, New York City was a center for theBeaux-Arts architectural movement, attracting the talents of such great architects asStanford White andCarrere and Hastings. As better construction and engineering technology became available as the century progressed, New York City and Chicago became the focal point of the competition for the tallest building in the world. Each city's striking skyline has been composed of numerous and varied skyscrapers, many of which are icons of 20th-century architecture:
TheE. V. Haughwout Building in Manhattan was the first building to successfully install a passenger elevator, doing so on 23 March 1857.[96]
TheWoolworth Building, a neo-Gothic "Cathedral of Commerce" overlookingNew York City Hall, was designed byCass Gilbert. At 792 feet (241 m), it became the world's tallest building upon its completion in 1913, an honor it retained until 1930.[103]
TheChrysler Building in New York City took the lead in late May 1930 as the tallest building in the world, reaching 1,046 feet (319 m).[106] Designed byWilliam Van Alen, anArt Deco style masterpiece with an exterior crafted of brick,[107] the Chrysler Building continues to be a favorite of New Yorkers to this day.[108]
TheEmpire State Building, nine streets south of the Chrysler in Manhattan, topped out at 1,250 feet (381 m) and 102 stories in 1931. The first building to have more than 100 floors, it was designed byShreve, Lamb and Harmon in the contemporaryArt Deco style and takes its name from thenickname ofNew York State. The antenna mast added in 1951 brought pinnacle height to 1,472 feet (449 m), lowered in 1984 to 1,454 feet (443 m).[109]
TheWorld Trade Center byMinoru Yamasaki officially surpassed the Empire State Building in 1970, was completed in 1973, and consisted of two tall towers and several smaller buildings. For a short time the World Trade Center's North Tower―completed in 1972―was the world's tallest building, until surpassed by theSears Tower in 1973. Upon completion, the towers stood for 28 years, until theSeptember 11 attacks destroyed the buildings in 2001.
TheSears Tower (now known as Willis Tower) was completed in 1974. It was the first building to employ the "bundled tube" structural system, designed byFazlur Khan. It was surpassed in height by thePetronas Towers in 1998, but remained the tallest in some categories untilBurj Khalifa surpassed it in all categories in 2010. It is currently the third tallest building in the United States, afterOne World Trade Center (which was built following 9/11), andCentral Park Tower inNew York City.
Momentum in setting records passed from the United States to other nations with the opening of thePetronas Twin Towers in Kuala Lumpur, Malaysia, in 1998. The record for the world's tallest building has remained in Asia since the opening ofTaipei 101 in Taipei, Taiwan, in 2004. A number of architectural records, including those of the world's tallest building and tallest free-standing structure, moved to the Middle East with the opening of theBurj Khalifa in Dubai, United Arab Emirates.
This geographical transition is accompanied by a change in approach to skyscraper design. For much of the 20th century large buildings took the form of simple geometrical shapes. This reflected the "international style" ormodernist philosophy shaped byBauhaus architects early in the century. The last of these, the Willis Tower and World Trade Center towers in New York, erected in the 1970s, reflect the philosophy. Tastes shifted in the decade which followed, and new skyscrapers began to exhibitpostmodernist influences. This approach to design avails itself of historical elements, often adapted and re-interpreted, in creating technologically modern structures. The Petronas Twin Towers recall Asianpagoda architecture and Islamic geometric principles. Taipei 101 likewise reflects thepagoda tradition as it incorporates ancientmotifs such as theruyi symbol. The Burj Khalifa draws inspiration from traditionalIslamic art. Architects in recent years[when?] have sought to create structures that would not appear equally at home if set in any part of the world, but that reflect the culture thriving in the spot where they stand.[citation needed]
The following list measures height of the roof, not the pinnacle.[110][failed verification] The more common gauge is the "highest architectural detail"; such ranking would have included Petronas Towers, built in 1996.
Proposals for such structures have been put forward, including the Burj Mubarak Al Kabir in Kuwait andAzerbaijan Tower inBaku. Kilometer-plus structures present architectural challenges that may eventually place them in a new architectural category.[111] The first building under construction and planned to be over one kilometre tall is theJeddah Tower.
The 25-storyAscent MKE is the world highest mass timber structure.[112]
Several wooden skyscraper designs have been designed and built. A 14-story housing project inBergen, Norway known as 'Treet' or 'The Tree' became the world's tallest wooden apartment block when it was completed in late 2015.[113] The Tree's record was eclipsed byBrock Commons, an 18-story woodendormitory at theUniversity of British Columbia in Canada, when it was completed in September 2016.[114]
A 40-story residential building 'Trätoppen' has been proposed by architect Anders Berensson to be built inStockholm, Sweden.[115] Trätoppen would be the tallest building in Stockholm, though there are no immediate plans to begin construction.[116] The tallest currently-planned wooden skyscraper is the 70-storyW350 Project in Tokyo, to be built by the Japanese wood products company Sumitomo Forestry Co. to celebrate its 350th anniversary in 2041.[117] An 80-story wooden skyscraper, the River Beech Tower, has been proposed by a team including architectsPerkins + Will and theUniversity of Cambridge. The River Beech Tower, on the banks of theChicago River inChicago, Illinois, would be 348 feet shorter than the W350 Project despite having 10 more storys.[118][117]
Wooden skyscrapers are estimated to be around a quarter of the weight of an equivalentreinforced-concrete structure as well as reducing the building carbon footprint by 60–75%. Buildings have been designed usingcross-laminated timber (CLT) which gives a higher rigidity and strength to wooden structures.[119] CLT panels are prefabricated and can therefore save on building time.[120]
^Petruzzello, Melissa."Skyscraper".Encyclopædia Britannica. Retrieved21 February 2022.Skyscraper, very tall, multistoried building. The name first came into use during the 1880s, shortly after the first skyscrapers were built, in the United States. The development of skyscrapers came as a result of the coincidence of several technological and social developments. The term skyscraper originally applied to buildings of 10 to 20 stories, but by the late 20th century the term was used to describe high-rise buildings of unusual height, generally greater than 40 or 50 stories.
^abAmbrose, Gavin; Harris, Paul; Stone, Sally (2008).The Visual Dictionary of Architecture. Switzerland: AVA Publishing SA. p. 233.ISBN978-2-940373-54-3.Skyscraper: A tall, multi-story building. Skyscrapers are different from towers or masts because they are habitable. The term was first applied during the late-nineteenth century, as the public marvelled at the elevated, steel-frame buildings being erected in Chicago and New York, USA. Modern skyscrapers tend to be constructed from reinforced concrete. As a general rule, a building must be at least 150 metres high to qualify as a skyscraper.
^"Magical Hystory Tour: Skyscrapers". 15 August 2010. Archived fromthe original on 29 June 2015.No one is certain which was the first true skyscraper, but Chicago's ten-story Home Insurance Building (1885) is a top contender.
^Charles E. Peterson (October 1950). "Ante-Bellum Skyscraper".Journal of the Society of Architectural Historians.9 (3):25–28.doi:10.2307/987464.JSTOR987464.In the annals of the American skyscraper there was, perhaps, nothing more daring than John McArthur, Jr.'s design for the Jayne Granite building, erected on lower Chestnut Street near the Philadelphia riverfront, just a century ago (FIG. 2). More than a generation older than the celebrated works of Louis Sullivan in Chicago and St. Louis. [..] Sullivan was for several months a cub draftsman in Furness and Hewitt's office just across the street. Although he does not seem to have mentioned in his writings Dr. Jayne's "proud and soaring" patent medicine headquarters, we may well wonder if some of the famous skyscraper designs of Chicago and St. Louis do not owe a real debt to Philadelphia.
^"Magical Hystory Tour: Skyscrapers". 15 August 2010. Archived fromthe original on 29 June 2015.The thirteen-story Tower Building (1889) just down the avenue at 50 Broadway, was the first New York skyscraper to use skeletal steel construction.
^Ivars Peterson (5 April 1986)."The first skyscraper – new theory that Home Insurance Building was not the first". CBS Interactive. Archived fromthe original on 8 July 2012. Retrieved6 January 2010."In my view, we can no longer argue that the Home Insurance Building was the first skyscraper," says Carl W. Condit, now retired from Northwestern University in Evanston, Ill., and author of several books on Chicago architecture. "The claim rests on an unacceptably narrow idea of what constitutes a high-rise commercial building," he says. "If there is a building in which all these technical factors—structural system, elevator, utilities—converge at the requisite level of maturity," argues Condit, "it's the Equitable Life Assurance Building in New York." Completed in 1870, the building rose 7½ stories, twice the height of its neighbors.
^"Huge New Rogers Skyscraper Proposed". skyscrapernews.com. 3 December 2007. Archived fromthe original on 4 October 2018. Retrieved3 December 2007....their eleventh proper skyscraper, that is by definition buildings above 150 metres
^Data Standards: skyscraper (ESN 24419),Emporis Standards, accessed on line July 2020. "A skyscraper is defined on Emporis as a multi-story building whose architectural height is at least 100 meters. This definition falls midway between many common definitions worldwide, and is intended as a metric compromise which can be applied across the board worldwide"
^Hultin, Olof; Bengt O H Johansson; Johan Mårtelius; Rasmus Wærn (1998).The Complete Guide to Architecture in Stockholm. Stockholm: Arkitektur Förlag. p. 62.ISBN978-91-86050-43-6.
^abLeung, Luke (December 2013). "Low-energy Tall Buildings? Room for Improvement as Demonstrated by New York City Energy Benchmarking Data".International Journal of High-Rise Buildings.2.S2CID6166727.
^Equitable Life Assurance Society of the United States (November 1901)."The Elevator Did It".The Equitable News: An Agents' Journal (23): 11.Archived from the original on 12 October 2013. Retrieved10 January 2012.
Judith Dupré.Skyscrapers: A History of the World's Most Extraordinary Buildings-Revised and Updated. (2013). Hachette/Black Dog & Leventhal. 2013 ed.:ISBN978-1-57912-942-2
Skyscrapers: Form and Function, by David Bennett, Simon & Schuster, 1995.
_edit.jpg)
.jpeg)
.JPG)
.jpg)
.jpg)
_(cropped).jpg)
.jpg)
.jpg)
_(cropped)_2.jpg)
.jpg)
.jpg)
_(2).jpg)
.jpg)
.jpg)
