Skyscraper

A skyscraper is a tall continuously habitable building having multiple floors. Modern sources currently define skyscrapers as being at least or in height, though there is no universally accepted definition. Skyscrapers are very tall high-rise buildings. Historically, the term first referred to buildings with between 10 and 20 stories when these types of buildings began to be constructed in the 1880s. Skyscrapers may host offices, hotels, residential spaces, and retail spaces.

One common feature of skyscrapers is having a steel frame that supports curtain walls. These curtain walls either bear on the framework below or are suspended from the framework above, rather than resting on load-bearing walls of conventional construction. Some early skyscrapers have a steel frame that enables the construction of load-bearing walls taller than of those made of reinforced concrete.

Modern skyscrapers' walls are not load-bearing, and most skyscrapers are characterised 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 a tubular structure, and are designed to act like a hollow cylinder 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 with setbacks, which in some cases is also structurally required.

, fourteen cities in the world have more than 100 skyscrapers that are or taller: Hong Kong with 518 skyscrapers; Shenzhen, China with 343 skyscrapers; New York City, US with 300 skyscrapers; Dubai, UAE with 237 skyscrapers; Mumbai, India with 208 skyscrapers; Shanghai, China with 180 skyscrapers; Tokyo, Japan with 165 skyscrapers; Guangzhou, China with 152 skyscrapers; Kuala Lumpur, Malaysia with 148 skyscrapers; Chongqing, China, and Chicago, US, both with 135 skyscrapers; Wuhan, China with 109 skyscrapers; and Bangkok, Thailand, and Jakarta, Indonesia, both with 108 skyscrapers.

Definition

The term "skyscraper" was first applied to buildings of steel-framed construction of at least 10 storeys in the late 19th century, a result of public amazement at the tall buildings being built in major American cities like Chicago, New York City, Philadelphia, Detroit, and St. Louis.

The first steel-frame skyscraper was the Home Insurance Building, originally 10 stories with a height of , in Chicago in 1885; two additional stories were added. Some point to Philadelphia's 10-storey Jayne Building (1849–50) as a proto-skyscraper, or to New York's seven-floor Equitable Life Building, built in 1870. Steel skeleton construction has allowed for today's supertall skyscrapers now being built worldwide. The nomination of one structure versus another being the first skyscraper, and why, depends on what factors are stressed.

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-storey 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.

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

Some structural engineers define a highrise as any vertical construction for which wind is a more significant load factor than earthquake or weight. Note that this criterion fits not only high-rises but some other tall structures, such as towers.

Different organizations from the United States and Europe define skyscrapers as buildings at least 150 metres in height or taller,"Which World City Has The Most Skyscrapers?"
''The Urban Developer''. 11 March 2016. Retrieved 26 March 2018. "The majority of international organisations, such as the CTBUH and Emporis, define a skyscraper as a building that reaches or exceeds the height of 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" with " supertall" skyscrapers for buildings higher than and "megatall" skyscrapers for those taller than .

The tallest structure in ancient times was the Great Pyramid of Giza in ancient Egypt, built in the 26th century BC. It was not surpassed in height for thousands of years, the Lincoln Cathedral having exceeded it in 1311–1549, before its central spire collapsed. The latter in turn was not surpassed until the Washington Monument in 1884. However, being uninhabited, none of these structures actually comply with the modern definition of a skyscraper.

High-rise apartments flourished in classical antiquity. Ancient Roman insulae in imperial cities reached 10 and more storeys. Beginning with Augustus (r. 30 BC-14 AD), several emperors attempted to establish limits of 20–25 m for multi-storey buildings, but were met with only limited success. Lower floors were typically occupied by shops or wealthy families, with the upper rented to the lower classes. Surviving Oxyrhynchus Papyri indicate that seven-storey buildings existed in provincial towns such as in 3rd century AD Hermopolis in Roman Egypt.

The skylines of many important medieval cities had large numbers of high-rise urban towers, built by the wealthy for defense and status. The residential Towers of 12th century Bologna numbered between 80 and 100 at a time, the tallest of which is the high Asinelli Tower. A Florentine law of 1251 decreed that all urban buildings be immediately reduced to less than 26 m.Werner Müller: "dtv-Atlas Baukunst I. Allgemeiner Teil: Baugeschichte von Mesopotamien bis Byzanz", 14th ed., 2005, , p.345 Even medium-sized towns of the era are known to have proliferations of towers, such as the 72 up to 51 m height in San Gimignano.

The medieval Egyptian city of Fustat housed many high-rise residential buildings, which Al-Muqaddasi in the 10th century described as resembling minarets. Nasir Khusraw in the early 11th century described some of them rising up to 14 storeys, with roof gardens on the top floor complete with ox-drawn water wheels for irrigating them. Cairo in the 16th century had high-rise apartment buildings where the two lower floors were for commercial and storage purposes and the multiple storeys above them were rented out to tenants. An early example of a city consisting entirely of high-rise housing is the 16th-century city of Shibam in Yemen. Shibam was made up of over 500 tower houses, each one rising 5 to 11 storeys high, with each floor being an apartment occupied by a single family. The city was built in this way in order to protect it from Bedouin attacks. Shibam still has the tallest mudbrick buildings in the world, with many of them over high.

An early modern example of high-rise housing was in 17th-century Edinburgh, 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 storeys were common, and there are records of buildings as high as 14 storeys. 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, is The Flaxmill (also locally known as the "Maltings"), in Shrewsbury, 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.

Early skyscrapers

In 1857, Elisha Otis introduced the safety elevator at the E.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 the Equitable 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 was Oriel Chambers in Liverpool, England. It was only five floors high. The Royal 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 glass curtain wall, a design element which creates light, airy interiors and has since been used the world over as a defining feature of skyscrapers".

Further developments led to what many individuals and organizations consider the world's first skyscraper, the ten-story Home Insurance Building in Chicago, built in 1884–1885. While its original height of 42.1 m (138 ft) does not even qualify as a skyscraper today, it was record setting. The building of tall buildings in the 1880s gave the skyscraper its first architectural movement, broadly termed the Chicago School, which developed what has been called the Commercial Style.

The architect, Major William 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 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.

Burnham and Root's Rand McNally Building in Chicago, 1889, was the first all-steel framed skyscraper, while Louis Sullivan's Wainwright Building in St. Louis, Missouri, 1891, was the first steel-framed building with soaring vertical bands to emphasize the height of the building and is therefore considered to be the first early skyscraper. In 1889, the Mole Antonelliana in Italy was 167 m (549 ft) tall.

Most early skyscrapers emerged in the land-strapped areas of Chicago and New York City toward the end of the 19th century. A land boom in Melbourne, 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 obstruct protected views of St Paul's Cathedral and other historic buildings. This policy, 'St Paul’s Heights', has officially been in operation since 1937.

Concerns about aesthetics and fire safety had likewise hampered the development of skyscrapers across continental Europe for the first half of the 20th century. Some notable exceptions are the tall 1898 Witte Huis ''(White House)'' in Rotterdam; the tall PAST Building (1906-1908) in Warsaw, the Royal Liver Building in Liverpool, completed in 1911 and high; the tall 1924 Marx House in Düsseldorf, Germany; the Kungstornen ''(Kings' Towers)'' in Stockholm, Sweden, which were built 1924–25, the Edificio Telefónica in Madrid, Spain, built in 1929; the Boerentoren in Antwerp, Belgium, built in 1932; the Prudential Building in Warsaw, Poland, built in 1934; and the Torre Piacentini in Genoa, Italy, built in 1940.

After an early competition between Chicago and New York City for the world's tallest building, New York took the lead by 1895 with the completion of the tall American Surety Building, leaving New York with the title of the world's tallest building for many years.

Modern skyscrapers

Modern skyscrapers are built with steel or reinforced concrete frameworks and curtain walls of glass or polished stone. They use mechanical equipment such as water pumps and elevator