Tower block


A tower block, high-rise, apartment tower, residential tower, apartment block, block of flats, or office tower is a tall building, as opposed to a low-rise building and is defined differently in terms of height depending on the jurisdiction. It is used as a residential or office building, or has other functions, including hotel, retail, or with multiple purposes combined. Residential high-rise buildings are also known in some varieties of English, such as British English, as tower blocks and may be referred to as MDUs, standing for multi-dwelling units. A very tall high-rise building is referred to as a skyscraper.
High-rise buildings became possible to construct with the invention of the elevator and with less expensive, more abundant building materials. The materials used for the structural system of high-rise buildings are reinforced concrete and steel. Most North American–style skyscrapers have a steel frame, while residential blocks are usually constructed of concrete. There is no clear difference between a tower block and a skyscraper, although a building with forty or more stories and taller than is generally considered a skyscraper.
High-rise structures pose particular design challenges for structural and geotechnical engineers, particularly if situated in a seismically active region or if the underlying soils have geotechnical risk factors such as high compressibility or bay mud. They also pose serious challenges to firefighters during emergencies in high-rise structures. New and old building design, building systems such as the building standpipe system, HVAC systems, fire sprinkler systems, and other things such as stairwell and elevator evacuations pose significant problems. Studies are often required to ensure that pedestrian wind comfort and wind danger concerns are addressed. In order to allow less wind exposure, to transmit more daylight to the ground and to appear more slender, many high-rises have a design with setbacks.
Apartment buildings have technical and economic advantages in areas of high population density, and have become a distinctive feature of housing accommodation in virtually all densely populated urban areas around the world. In contrast with low-rise and single-family houses, apartment blocks accommodate more inhabitants per unit of area of land and decrease the cost of municipal infrastructure.

Definition

Various bodies have defined "high-rise":
  • Emporis defines a high-rise as "A multi-story structure between tall, or a building of unknown height from 12–39 floors."
  • The New Shorter Oxford English Dictionary defines a high-rise as "a building having many storeys".
  • The International Conference on Fire Safety in High-Rise Buildings defined a high-rise as "any structure where the height can have a serious impact on evacuation"
  • In the U.S., the National Fire Protection Association defines a high-rise as being higher than, or about seven stories.
  • Most building engineers, inspectors, architects and similar professionals define a high-rise as a building that is at least 75 feet tall.

    History

High-rise apartment buildings had already appeared in antiquity: the insulae in Ancient Rome and several other cities in the Roman Empire, some of which might have reached up to ten or more stories, one reportedly having 200 stairs. Because of the destruction caused by poorly built high-rise insulae collapsing, several Roman emperors, beginning with Augustus, set limits of for multi-story buildings, but met with limited success, as these limits were often ignored despite the likelihood of taller insulae collapsing. The lower floors were typically occupied by either shops or wealthy families, while the upper stories were rented out to the lower classes. Surviving Oxyrhynchus Papyri indicate that seven-story buildings even existed in provincial towns, such as in third century AD Hermopolis in Roman Egypt.
In Arab Egypt, the initial capital city of Fustat housed many high-rise residential buildings, some seven stories tall that could reportedly accommodate hundreds of people. Al-Muqaddasi, in the 10th century, described them as resembling minarets, while Nasir Khusraw, in the early 11th century, described some of them rising up to 14 stories, with roof gardens on the top story complete with ox-drawn water wheels for irrigating them. By the 16th century, Cairo also had high-rise apartment buildings where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants.
The skyline of many important medieval cities was dominated by large numbers of high-rising urban towers, which fulfilled defensive but also representative purposes. The residential Towers of Bologna numbered between 80 and 100 at a time, the largest of which still rise to 97.2 m. In Florence, a law of 1251 decreed that all urban buildings should be reduced to a height of less than 26 m, the regulation immediately put into effect. Even medium-sized towns such as San Gimignano are known to have featured 72 towers up to 51 m in height.
The Hakka people in southern China have adopted communal living structures designed to be easily defensible in the forms of weilongwu, as well as tulou , often abbreviated to yuanlou ; the latter are large, enclosed and fortified earth buildings, between two and five stories high and housing up to 80 families. The oldest still standing tulou dates back from the 14th century.
High-rises were built in the Yemeni city of Shibam in the 16th century. The houses of Shibam are all made out of mud bricks, but about five hundred of them are tower houses, which rise five to sixteen stories high, with each floor having one or two apartments. This technique of building was implemented to protect residents from Bedouin attacks. While Shibam has existed for around two thousand years, most of the city's houses date from the 16th century. The city has the tallest mud buildings in the world, some more than 30 meters high. Shibam has been called "one of the oldest and best examples of urban planning based on the principle of vertical construction" or "Manhattan of the desert".
The engineer's definition of high-rise buildings comes from the development of fire trucks in the late 19th century. Magirus had shown the first cogwheel sliding ladder in 1864. The first turntable ladder drawn by horses was developed in 1892 which had a length of 25 meters. The extension ladder was motorized by Magirus in 1904. The definition of a maximum of 22 meters for the highest floor was common in the building regulations at the time and it is still so today in Germany. The common height for turntable ladders did later go to 32 meters, so that 30 meters is a common limit in some building regulations today, for example in Switzerland. Any building that exceeds the height of the usual turntable ladders in a city must install additional fire safety equipment, so that these high-rise buildings have a different section in the building regulations in the world.
File:Y House.JPG|thumb|A residential block in Steinfurt, Westphalia, Germany, forming a "Y"
The residential tower block with its typical concrete construction is a familiar feature of Modernist architecture. Influential examples include Le Corbusier's "housing unit", his Unité d'Habitation, repeated in various European cities starting with his Cité radieuse in Marseille, constructed of béton brut, rough-cast concrete, as steel for framework was unavailable in post-war France. Residential tower blocks became standard in housing urban populations displaced by slum clearances and "urban renewal". High-rise projects after World War II typically rejected the classical designs of the early skyscrapers, instead embracing the uniform international style; many older skyscrapers were redesigned to suit contemporary tastes or even got demolished - such as New York's Singer Building, once the world's tallest skyscraper. However, with the movements of Postmodernism, New Urbanism, and New Classical Architecture, that established since the 1980s, a more classical approach came back to global skyscraper design, that is popular today.
Other contemporary styles and movements in high-rise design include organic, sustainable, neo-futurist, structuralist, high-tech, deconstructivist, blob, digital, streamline, novelty, critical regionalist, vernacular, Art Deco, and neohistorist, also known as revivalist.
Currently, the tallest high-rise apartment building in the world is the Central Park Tower on Billionaires' Row in Midtown Manhattan, towering at.

Streets in the sky

Streets in the sky is a style of architecture that emerged in Britain in the 1960s and 1970s. Generally built to replace run-down terraced housing, the new designs included not only modern improvements such as inside toilets, but also shops and other community facilities within high-rise blocks. Examples of the buildings and developments are Trellick Tower, Balfron Tower, Broadwater Farm, Robin Hood Gardens and Keeling House in London, Hunslet Grange in Leeds and Park Hill, Sheffield, and Castlefields and Southgate Estate, Runcorn. These were an attempt to develop a new architecture, differentiated from earlier large housing estates, such as Quarry Hill flats in Leeds. Alison and Peter Smithson were the architects of Robin Hood Gardens. As another large example, in 2005 it was decided to carry out a 20-year process of demolition and replacement of dwellings with modern houses in the Aylesbury Estate in south London, built in 1970. The Hulme Crescents in Manchester were the largest social housing scheme in Europe when built in 1972 but lasted just 22 years. The Crescents had one of the worst reputations of any British social housing schemes and were marred by numerous design and practical problems.
The ideal of Streets in the Sky worked rarely in practice. Unlike an actual city street, these walkways were not thoroughfares, and often came to a dead end multiple storeys above the ground. They lacked a regular flow of passers-by, and the walkways and especially the stairwells could not be seen by anyone elsewhere, so there was no deterrent to crime and disorder. There were no "eyes on the street" as advocated by Jane Jacobs in her book The Death and Life of Great American Cities. The Unité d'Habitation in Marseille provides a more successful example of the concept, with the fifth floor walkway including a shop and café.