Arch facts for kids

An arch

An arch is an opening in a building that is curved on top. The curved part can be round, like part of a circle, or pointed, like two parts of circles next to each other. Arches are often used where buildings are made of lots of small stones or bricks. The stone at the very top of the arch, called the keystone, keeps the rest of the arch stones from falling down. Arches can go over doorways and windows. Many bridges are arches.

Basic concepts

An arch is a soft compression form. It can span a large area by resolving forces into compressive stresses and, in turn eliminating tensile stresses. This is sometimes referred to as arch action. As the forces in the arch are carried to the ground, the arch will push outward at the base, called thrust. As the rise, or height of the arch decreases, the outward thrust increases. In order to maintain arch action and prevent the arch from collapsing, the thrust needs to be restrained, either with internal ties or external bracing, such as abutments.

Fixed vs hinged arch

Rossgraben bridge (Rüeggisberg) near Bern, Switzerland, showing the hinge at mid-span of this three-hinged arch.

The most common true arch configurations are the fixed arch, the two-hinged arch, and the three-hinged arch.

The fixed arch is most often used in reinforced concrete bridge and tunnel construction, where the spans are short. Because it is subject to additional internal stress caused by thermal expansion and contraction, this type of arch is considered to be statically indeterminate.

The two-hinged arch is most often used to bridge long spans. This type of arch has pinned connections at the base. Unlike the fixed arch, the pinned base is able to rotate, allowing the structure to move freely and compensate for the thermal expansion and contraction caused by changes in outdoor temperature. However, this can result in additional stresses, so the two-hinged arch is also statically indeterminate, although not to the degree of the fixed arch.

The three-hinged arch is not only hinged at its base, like the two-hinged arch, but at the mid-span as well. The additional connection at the mid-span allows the three-hinged arch to move in two opposite directions and compensate for any expansion and contraction. This type of arch is thus not subject to additional stress caused by thermal change. The three-hinged arch is therefore said to be statically determinate. It is most often used for medium-span structures, such as large building roofs.

Another advantage of the three-hinged arch is that the pinned bases are more easily developed than fixed ones, allowing for shallow, bearing-type foundations in medium-span structures. In the three-hinged arch, "thermal expansion and contraction of the arch will cause vertical movements at the peak pin joint but will have no appreciable effect on the bases," further simplifying the foundation design.

Types of arches

Arches have many forms, but all fall into three basic categories: circular, pointed, and parabolic. Arches can also be configured to produce vaults and arcades.

Arches with a circular form, also referred to as rounded arches, were commonly employed by the builders of ancient, heavy masonry arches. Ancient Roman builders relied heavily on the rounded arch to span large, open areas. Several rounded arches placed in-line, end-to-end, form an arcade, such as the Roman aqueduct.

Semi-circular arches using brick and/or stone block construction at the Great Wall, China

Roman aqueduct near Nîmes, France: an arcade, employing the circular arch

Horseshoe arches in the 9th-century Mosque of Uqba, in Kairouan, Tunisia

Pointed arches were most often used by builders of Gothic-style architecture. The advantage to using a pointed arch, rather than a circular one, is that the arch action produces less thrust at the base. This innovation allowed for taller and more closely spaced openings, typical of Gothic architecture.

Cathedral of St. Michael and St. Gudula in Brussels, Belgium, with a central pointed arch window, typical of Gothic architecture

Vaults are essentially "adjacent arches [that] are assembled side by side." If vaults intersect, complex forms are produced with the intersections. The forms, along with the "strongly expressed ribs at the vault intersections, were dominant architectural features of Gothic cathedrals."

Interior vaulted ceiling of Notre Dame de Paris, showing the ribs at the intersection of several arches

The parabolic arch employs the principle that when weight is uniformly applied to an arch, the internal compression resulting from that weight will follow a parabolic profile. Of all arch types, the parabolic arch produces the most thrust at the base, but can span the largest areas. It is commonly used in bridge design, where long spans are needed.

Tyne Bridge in Newcastle upon Tyne, England: a parabolic arch used in bridge design

A series of parabolic arches on the Móra d'Ebre bridge, Catalonia

The catenary arch has a shape different from the parabolic curve. The shape of the curve traced by a loose span of chain or rope, the catenary is the structurally ideal shape for a freestanding arch of constant thickness.

Types of arches displayed chronologically, roughly in the order in which they were developed:

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  Triangular arch

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  Round arch, or semi-circular arch

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  Segmental arch is less than a semicircle

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  Unequal round arch, or rampant round arch

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  Lancet arch

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  Equilateral pointed arch

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  Shouldered flat arch (see also: jack arch)

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  Trefoil arch, or three-foiled cusped arch

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  Horseshoe arch

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  Three-centered arch

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  Elliptical arch

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  Inflexed arch

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  Ogee arch

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  Reverse ogee arch

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  Tudor arch

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  Parabolic arch

Other types

Delicate Arch, a natural arch in Arches National Park near Moab, Utah

A rock balance sculpture in the form of an arch

A blind arch is an arch infilled with solid construction so it cannot function as a window, door, or passageway.

A special form of the arch is the triumphal arch, usually built to celebrate a victory in war. A famous example is the Arc de Triomphe in Paris, France.

Rock formations may form natural arches through erosion, rather than being carved or constructed. Structures such as this can be found in Arches National Park.

Some rock balance sculptures are in the form of an arch.

The arches of the foot support the weight of the human body.

Images for kids

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  Deformed arch at the Gozo Aqueduct, Malta

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  Roman aqueduct near Nîmes, France: an arcade, employing the circular arch

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  Arch of Caracalla, a Roman triumphal arch in Tébessa, Algeria (2016)

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  Depressed Tudor arch on Layer Marney Tower in Essex, England

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  Blind arches on the Church of San Tirso in Sahagún, León, Spain

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  Washington Square Arch, a triumphal arch in Greenwich Village, Manhattan, New York City

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  Delicate Arch, a natural arch in Arches National Park near Moab, Utah

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  A rock balance sculpture in the form of an arch

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  Medial longitudinal arch of the human foot (Gray's Anatomy)

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  Restored Canaanite city gate of Ashkelon, Ashkelon, Israel (2014)

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  Reconstructed Ishtar Gate of Babylon in the Pergamon Museum, Berlin (2014)

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  Taq Kasra (Archway of Ctesiphon), Salman Pak, Iraq (1864)

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  Arch of Augustus, Rimini, Emilia-Romagna, Italy (2015)

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  Arch of Gallienus, Rome (2006)

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  Arch of Hadrian, Athens, Greece (2013)

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  Arch of Constantine, Rome, commemorating a victory by Constantine I in 312 AD (2007)

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  The Arc de Triomphe, Paris; a 19th-century triumphal arch modelled on the classical Roman design (1998)

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  Soldiers' and Sailors' Arch in the Grand Army Plaza, Brooklyn, New York City (2007)

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  Gateway Arch in St. Louis, Missouri; a monument based on a catenary arch (2011)

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  The Theme Building at Los Angeles International Airport, California

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  Pont Flavien over the River Touloubre in Saint-Chamas, Bouches-du-Rhône, France (2008)

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  Old stone bridge in Kerava, Finland (2011)

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  Bridge of Seonamsa Temple, Suncheon, South Jeolla Province, South Korea (1979)

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  Grosvenor Bridge over the River Dee in Chester, Cheshire, England, UK (2007)

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  Union Arch Bridge carrying the Washington Aqueduct and MacArthur Boulevard (formerly named Conduit Road) in Cabin John, Montgomery County, Maryland (2008)

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  Anji Bridge over the Xiaohe River, Hebei Province, China (2007)

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  The dry stone bridge, so called Porta Rosa (4th century BC), in Elea, Province of Salerno, Campania, Italy (2005)

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  Bridge of Sighs, Venice, Italy (2001)

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  Pont du Gard, a Roman aqueduct in Vers-Pont-du-Gard, Gard, France (2014)

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  Bridge in Český Krumlov, Czech Republic (2004)

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  Rialto Bridge over the Grand Canal in Venice, Italy (2011)

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  Pont de Bercy over the River Seine, Paris, carrying the Paris Métro on its upper deck and a boulevard extension on its lower deck (2006)

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  Arlington Memorial Bridge over the Potomac River in Washington, D.C. (2007)

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  Francis Scott Key Bridge over the Potomac River in Washington, D.C. (2006)

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  Woodrow Wilson Memorial Bridge carrying Interstate 95 (I-95) and the Capital Beltway over the Potomac River between Alexandria, Virginia and Oxon Hill, Maryland (2007)

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  Arrábida Bridge over the Douro River connecting Porto, and Vila Nova de Gaia, in the Norte Region, Portugal (2011)

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  Rainbow Bridge over the Niagara River connecting Niagara Falls, New York and Niagara Falls, Ontario, Canada (2012)

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  Hell Gate Bridge over the East River, New York City

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  Sydney Harbour Bridge, Sydney, New South Wales, Australia (2010)

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  Ludendorff Bridge over the Rhine River, Remagen, Germany, showing damage before collapse during the Battle of Remagen in World War II (1945)

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  Lianxiang bridge over the Xiang River, Xiangtan, Hunan Province, China (2007)

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  Zhivopisny Bridge over the Moskva River, Moscow, Russia (2009)

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  Margaret Hunt Hill Bridge over the Trinity River in Dallas, Texas (2012)

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  Juscelino Kubitschek Bridge crossing Paranoá Lake, Brasília, Brazil (2007)

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  Gateshead Millennium Bridge over the River Tyne, Newcastle upon Tyne, England, UK (2005)

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  Eiffel Tower, Paris (2009)

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  Arch supporting the Eiffel Tower, Paris (2015)

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  The second Wembley Stadium in London, built in 2007 (2007)

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  The first San Mamés Stadium, in Bilbao, arch built in 1953, demolished 2013 (2013)

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  St Pancras railway station, London (2011)

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  Train shed in St Pancras railway station, London (2010)

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  Train shed in Victoria Station, London (2006)

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  Lucerne railway station, Switzerland (2010)

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  Central railway station, Frankfurt, Germany (2008)

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  Train shed in Central railway station, Frankfurt, Germany (2005)

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  Arches in Main Concourse, Grand Central Terminal, Manhattan, New York City (2014)

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  Interior arches in Washington Union Station, Washington, D.C. (2006)

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  Arches in Great Hall, Chicago Union Station, Chicago, Illinois (2010)

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  Haus der Kulturen der Welt, Berlin, Germany (2011)

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  The Colosseum in Rome (2013)

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  Stonework arches seen in a ruined stonework building – Burg Lippspringe, Germany (2005)

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  Arches in the Casa-Museo del Libertador Simón Bolívar in Havana, Cuba (2006)

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  Arches in dining hall at Kings College, University of Cambridge, Cambridge, England (2007)

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  Arches inside Annenberg Hall, Memorial Hall, Harvard University, Cambridge, Massachusetts (2016)

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  Healy Hall, Georgetown University, Washington, D.C. (2009)

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  Arches in throne room of Neuschwanstein Castle, Bavaria, Germany (1886 photochrom print)

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  Arches in the Court of the Lions, Alhambra, Granada, Andalusia, Spain (2012)

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  External arches in the Court of the Myrtles, Alhambra, Granada, Andalusia, Spain (2009)

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  Arches inside the North Gallery, Court of the Myrtles, Alhambra, Granada, Andalusia, Spain (2010)

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  Arches in the nave of the church in monastery of Alcobaça, Portugal (2008)

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  North facade of Chartres Cathedral, Chartres, France (2008)

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  Arches in choir of Chartres Cathedral, Chartres, France (2013)

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  Arches in nave of Westminster Abbey, City of Westminster, London (2006)

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  Arches inside the Washington National Cathedral, Washington, D.C. (2005)

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  Interior arches in St. Peter's Basilica, Vatican City (2009)

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  Amir Chakhmaq Complex, Yazd, Iran (2014)

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  Hagia Sophia in Istanbul, Turkey (2013)

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  Arches inside the Hagia Sophia in Istanbul, Turkey (1983)

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  Arches inside the western upper gallery, Hagia Sophia, Istanbul, Turkey (2007)

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  Interior arches in the Masjid al-Haram, Mecca, Saudi Arabia (2008)

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  Roof of Masjid al-Haram, Mecca, Saudi Arabia (2008)

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  Dome of the Rock, Old City of Jerusalem (2010)

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  Arches inside the Dome of the Rock, Old City of Jerusalem (2014)

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  Arches in the Shahi Mosque, Chitral, Khyber Pakhtunkhwa province, Pakistan (2016)

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  Taj Mahal in Agra, Uttar Pradesh, India (2009)

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  The Great Gate (Darwaza-i-rauza): Entrance to grounds of Taj Mahal, Agra, Uttar Pradesh, India (2004)

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  Arches inside the Taj Majal, Agra, Uttar Pradesh, India

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  Arches in Main Reading Room, Thomas Jefferson Building, Library of Congress, Washington, D.C. (2009)

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  Arches in Great Hall, Thomas Jefferson Building, Library of Congress, Washington, D.C. (2007)

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  Art Deco arches on Chrysler Building, Manhattan, New York City (2005)

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  New York Public Library Main Branch, Manhattan, New York City (2016)

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  Arches inside the entrance of New York Public Library Main Branch, Manhattan, New York City (2012)

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  Arches in Great Hall, Metropolitan Museum of Art, Manhattan, New York City (2012)

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  Arches in Sculpture Gallery, West Building, National Gallery of Art, Washington, D.C. (2007)

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  Arches inside the Legion of Honor, Lincoln Park, San Francisco, California (2010)

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  Arches near the Jordan Staircase, Winter Palace, Hermitage Museum, St. Petersburg, Russia (2015)

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  Arches in Pavilion Hall, Small Hermitage, Hermitage Museum, St. Petersburg, Russia (2015)

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  Arches in Salle du Manège, Louvre Palace, Paris (2007)

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  Arches in Galerie des Batailles, Palace of Versailles, Versailles, Yvelines, France (2013)

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  Arches in Hall of Mirrors, Palace of Versailles, Versailles, Yvelines, France (2011)

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  Arches in Westminster Hall, Palace of Westminster, City of Westminster, London (2011)

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  Arches in St. Stevens Hall, Palace of Westminster, City of Westminster, London (2007)

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  Horseshoe arch inside the Aljafería Palace, Zaragoza, Spain (2004)

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  Multifoil arches inside the Aljafería Palace, Zaragoza, Spain (2004)

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  Catenary arches inside the Casa Milà in Barcelona, Spain by Antoni Gaudí (2010}

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  Rajasthani style arches inside the 16th-century City Palace, Udaipur, India (2013)

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  Main façade of the Itamaraty Palace in Brasília, Brazil, decorated with many arches (2005)

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  Arches inside the National Building Museum (formerly Pension Building), Washington, D.C. (2007)

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  Front entrance of the Old Post Office Building in Washington, D.C. (2006)

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  Arches inside the Old Post Office Building in Washington, D.C. (2009)

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  Bankstown Reservoir, Bankstown, Sydney, New South Wales, Australia (2018)

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  Arches in Merzouga, Morocco (2011)

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  Crypt of the Popes in the Catacomb of Callixtus, Rome (2007)

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  Chinese Eastern Han Dynasty (25–220 AD) tomb chamber, Luoyang (2008)

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  Entrance to Washington family tomb at Mount Vernon, Fairfax County, Virginia (2014)

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  Natural Bridge in Rockbridge County, Virginia (2014)

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  Jiangzhou Natural Bridge, Guangxi Zhuang Autonomous Region, China (2012)

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  Landscape Arch, Arches National Park, Utah (2016)

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  Double O Arch, Arches National Park, Utah (2007)

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  Aloba Arch, Ennedi-Est Region, Chad (2015)

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  Shipton's Arch, Xinjiang Uygur Autonomous Region, China (2011)

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  Darwin's Arch, Galápagos Archipelago, Pacific Ocean (2006)

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  Shah Abbas Arch Dam (Tagh E Shah Abbas), Tabas County, South Khorasan Province, Iran (2011)

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  Hoover Dam in the Black Canyon of the Colorado River, Clark County, Nevada and Mohave County, Arizona (2017)

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  El Atazar Dam on the Lozoya River near Madrid, Spain (2014)

See also

In Spanish: Arco (arquitectura) para niños