Arch 52070 223592858 2008-07-04T19:57:44Z Lightbot 7178666 Units/dates/other {{Citations missing|date=December 2007}} {{otheruses}} [[Image:Arch illustration.svg|thumb|right|A masonry arch <br> 1.&nbsp;Keystone 2.&nbsp;Voussoir 3.&nbsp;Extrados 4.&nbsp;Impost 5.&nbsp;Intrados 6.&nbsp;Rise 7.&nbsp;Clear span 8.&nbsp;Abutment]] An '''arch''' is a structure capable of [[Span (architecture)|spanning]] a space while supporting significant weight (e.g. a doorway in a stone [[wall]]). True arches appeared as early as the 2nd millennium BC in [[Mesopotamia]]n brick architecture and in Persian ziggurats (see [[Chogha Zanbil]]). True arches were also built by the [[Babylonians]] in the 6th century BC (see [[Ishtar Gate]] ). The arch then spread to Europe and was adopted by the [[Ancient Greece|Ancient Greeks]], [[Etruscans]], and [[Ancient Rome|Ancient Romans]]. The arch became an important technique in [[medieval]] European [[cathedral]] building as well as Islamic architecture. Across the ocean in Mexico and Central America, [[Mesoamerican]] civilizations created various types of [[corbelled arch]]es, such as with the interior tunnels in the [[Great Pyramid of Cholula]] and the many styles of corbelled arches built by the [[Mayan]] civilization. In Peru, the [[Inca]] civilization used a trapezoidal arch in their architecture. The arch is still used today in some modern structures such as [[bridge]]s. ==History== [[Image:Bridge Alcantara.JPG|thumb|left|[[Roman bridge]] in [[Alcántara]], [[Spain]]]] [[Image:Sankt Petersburg Generalstab 2005 g.jpg|thumb|left|Arch of the General Staff Building in [[Palace Square]], [[St Petersburg]]]] [[Image:BaraKaram.jpg|thumb|left|The incomplete mausoleum of Adil Shah, Barakaman (Ali Roza-II), which means twelve arches in [[Urdu]]]] Arches were first created and used by the [[Mesopotamian]], [[Persian Empire|Persian]], [[Harappan architecture|Harappan]], [[Ancient Egypt|Egyptian]], [[Babylon]]ian, and [[Assyria]]n civilizations. Many arches were used in buildings and in monumental architecture, such as in the [[Ishtar Gate]] and the ziggurat of [[Chogha Zanbil]]. Other arches were used in underground structures such as drains where the problem of lateral thrust is greatly diminished. From the [[Middle East]], knowledge of arch building spread to Europe. The ancient [[Roman architecture|Romans]] learned the arch from the [[Etruscans]] (who originally migrated out of the Middle East), refined it and employed it for above ground buildings. Throughout the [[Roman empire]], their engineers erected arch structures such as [[Roman bridge|bridges]], [[Roman aqueduct|aqueducts]], and gates. They also introduced the [[triumphal arch]] as a military monument. [[Vault]]s began to be used for roofing large interior spaces such as halls and temples, a function which was also assumed by [[dome]]d structures from the 1st century BC onwards. The Roman arch is semicircular, and built from an odd number of arch bricks (called ''[[voussoir]]s''). An odd number of bricks is required for there to be a ''capstone'' or ''[[Keystone (architecture)|keystone]]'', the topmost stone in the arch. The Roman arch's shape is the simplest to build, but not the strongest. There is a tendency for the sides to bulge outwards, which must be counteracted by an added weight of [[masonry]] to push them inwards. The Romans used this type of semicircular arch freely in many of their secular structures such as aqueducts, palaces and amphitheaters.{{Fact|date=December 2007}} The semicircular arch was followed in Europe by the pointed [[Gothic architecture|Gothic arch]] or [[ogive]] (derived from the Islamic pointed arch in [[Islamic Spain|Moorish Spain]]), whose centreline more closely followed the forces of compression and which was therefore stronger. The semicircular arch can be flattened to make an [[ellipse|elliptical]] arch as in the [[Ponte Santa Trinita]]. The [[parabola|parabolic]] and [[catenary]] arches are now known to be the theoretically strongest forms. Parabolic arches were introduced in construction by the [[Spanish architecture|Spanish architect]] [[Antoni Gaudí]], who admired the structural system of [[Gothic style]], but for the buttresses, which he termed “architectural [[crutch]]es”. The catenary and parabolic arches carry all horizontal thrust to the foundation and so do not need additional elements. The horseshoe arch is based on the semicircular arch, but its lower ends are extended further round the circle until they start to converge. The first examples known are carved into rock in India in the first century AD, while the first known built horseshoe arches are known from [[Kingdom of Aksum|Aksum]] (modern day [[Ethiopia]] and [[Eritrea]]) from around the 3rd–4th century, around the same time as the earliest contemporary examples in [[Syria]], suggesting either an Aksumite or Syrian origin for the type of arch.<ref>Stuart Munro-Hay, ''Aksum: A Civilization of Late Antiquity''. Edinburgh: University Press. 1991. ISBN 0-7486-0106-6, p.111.</ref> It was used in Spanish Visigothic architecture, [[Islamic architecture]] and [[mudéjar|mudéjar architecture]], as in the Great [[Mosque]] of [[Damascus]] and in later [[Moorish]] buildings. It was used for decoration rather than for strength. In Mexico and Central America, [[Mesoamerican]] civilizations created various types of [[corbelled arch]]es, such as with the interior tunnels in the [[Great Pyramid of Cholula]] and the many styles of corbelled arches built by the [[Mayan]] civilization. ==Construction== [[Image:Valvbåge.png|thumb|right|[[Isometric projection|Isometric view]] of a typical arch]] An arch requires all of its elements to hold it together, raising the question of how an arch is constructed. One answer is to build a frame (historically, of wood) which exactly follows the form of the underside of the arch. This is known as a centre or [[centring]]. The [[voussoir]]s are laid on it until the arch is complete and self-supporting. For an arch higher than head height, scaffolding would in any case be required by the builders, so the scaffolding can be combined with the arch support. Occasionally arches would fall down when the frame was removed if construction or planning had been incorrect. (The [[A85 road|A85]] bridge at Dalmally, Scotland suffered this fate on its first attempt, in the 1940s). The interior and lower line or curve of an arch is known as the ''intrados''. Old arches sometimes need reinforcement due to decay of the keystones, known as '''[[bald arch]]'''. The gallery shows arch forms displayed in roughly the order in which they were developed. <div align="center"><gallery> Image:Treledsbåge.png|[[Triangular arch]] Image:Rundbåge.png|[[Round arch]] or Semi-circular arch Image:Segmentbåge.png|[[Segmental arch]] Image:Stigande båge.png|Unequal round arch or [[Rampant round arch]] Image:Lansettbåge.png|[[Lancet arch]] Image:Spetsbåge.png|[[Equilateral pointed arch]] Image:Skulderbåge.png|[[Shouldered flat arch]] -see also [[jack arch]] Image:Trepassbåge.png|Three-foiled [[cusped arch]] Image:Hästskobåge.png|[[Horseshoe arch]] Image:Korgbåge.png|[[Three-centered arch]] Image:Ellipsbåge.png|[[Elliptical arch]] Image:Draperibåge.png|[[Inflexed arch]] Image:Kölbåge.png|[[Ogee arch]] Image:Karnisbåge.png|[[Ogee arch|Reverse ogee arch]] Image:Tudorbåge.png|[[Tudor arch]] Image:Parabelbåge.png|[[Catenary]] or [[Parabolic]] arch </gallery></div> ==Technical aspects== [[Image:Gaoliang Bridge.JPG|thumb|left|thumb|When made from stone this becomes a true [[arch bridge]], requiring stone approaches for structural stability. Chinese moon bridge]] The arch is significant because, in theory at least, it provides a structure which eliminates [[tensile stress]]es in spanning an open space. All the forces are resolved into [[compressive stress]]es. This is useful because several of the available building materials such as [[Rock (geology)|stone]], [[cast iron]] and [[concrete]] can strongly resist compression but are very weak when [[Tensile stress|tension]], [[Shear stress|shear]] or [[torsion]]al stress is applied to them. By using the arch configuration, significant spans can be achieved. This is because all the compressive forces hold it together in a state of equilibrium. This even applies to frictionless surfaces. However, one downside is that an arch pushes outward at the base, and this needs to be restrained in some way, either with heavy sides and friction or angled cuts into bedrock or similar. This same principle holds when the [[force]] acting on the arch is not vertical such as in spanning a doorway, but horizontal, such as in arched [[retaining wall]]s or [[dam]]s. Even when using concrete, where the structure may be monolithic, the principle of the arch is used so as to benefit from the concrete's strength in resisting compressive stress. Where any other form of stress is raised, it has to be resisted by carefully placed [[Rebar|reinforcement rods]] or fibres. (See [[Arch bridge]].) ==Other types== [[Image:Delicatearch.jpg|thumb|right|The [[Delicate Arch]], a natural arch]][[Image:Arc de triomphe frontsimple.jpg|thumb|left|The Arc de Triomphe, Paris; a 19th century triumphal arch modeled on the classical [[Ancient Rome|Roman]] design.]]A [[blind arch]] is an arch infilled with solid construction so it cannot function as a window, door, or passageway. A [[dome]] is a three-dimensional application of the arch, rotated about the center axis. [[Igloo]]s are notable early structures making use of domes. Natural rock formations may also be referred to as arches. These [[natural arch]]es are formed by [[erosion]] rather than being carved or constructed by man. See [[Arches National Park]] for examples. 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]]. A [[Vault (architecture)|vault]] is an application of the arch extended horizontally in two dimensions; the [[groin vault]] is the intersection of two vaults. ==Gallery== <gallery> image:Velia.jpg|The [[dry stone]] bridge, so called ''Porta Rosa'' (4th century BC), in [[Velia (town)|Elea]] Image:arch.of.constantine.threequarter.view.arp.jpg|[[Arch of Constantine]], [[Rome]], [[Italy]] commemorating a victory by [[Constantine I]] in 312 AD Image:gateway_arch.jpg|The [[Jefferson National Expansion Memorial|Gateway Arch]] in [[Saint Louis, Missouri]]; a sculpture based on a [[catenary]] arch Image:Ig NSra Assuncao Linhares 2.jpg|Doubled round [[archivolt]]s - Igreja de Nossa Senhora da Assunção, Linhares da Beira, Portugal. Image:Bl-burg-innenhof-oben.jpg|Stonework arches seen in a ruined stonework building - Burg [[Bad Lippspringe|Lippspringe]], Germany Image:DirkvdM havana casa bolivar.jpg|Several arches at the Casa Simón Bolívar in [[Havana]], Cuba <!--two segmental arches and a round arch seen through a rampant arch, I think--> Image:Geghard gavit-IMG 2564.JPG|Arches in the [[Armenian Church|Armenian]] monastery of [[Geghard]]. <!-- Deleted image removed: Image:Han_Tomb_Arch_1.jpg|Recently discovered 1700 year old Han Tomb --> </gallery> ==References== {{commons|Arch|Arch}} <references/> *{{cite book | author=Roth, Leland M | title=Understanding Architecture: Its Elements History and Meaning | location=Oxford, UK | publisher=Westview Press | year=1993 | id=ISBN 0-06-430158-3}} pp. 27-8 == See also == * [[Corbelled arch]] * [[Blind arch]] * [[Suspension bridge]] * [[Triumphal arch]] * [[Natural arch]] ==External links== * [http://photos.igougo.com/pictures-photos-j41988-s2-p144161-Oldest_Known_Arch.html Oldest Known Arch In The World] Photography by a U.S. soldier serving in Iraq. * [http://www.diyinfo.org/wiki/Constructing_Brick_Arches DIYinfo.org's Constructing Brick Arches Wiki] - A wiki on how to construct brick arches around the house * [http://www.diyinfo.org/wiki/Constructing_Timber_Framed_Arches DIYinfo.org's Constructing Timber Framed Arches Wiki] - Similar to the brick arches but extra information for timber arches [[Category:Arch bridges]] [[Category:Arches and vaults| ]] <!--interwiki--> [[af:Boog (boukunde)]] [[ar:قوس]] [[zh-min-nan:Oân-kong]] [[be-x-old:Арка]] [[bg:Арка]] [[ca:Arc (arquitectura)]] [[cy:Bwa (pensaernïaeth)]] [[de:Bogen (Architektur)]] [[es:Arco (construcción)]] [[eo:Arko (arkitekturo)]] [[eu:Arku (arkitektura)]] [[fr:Arc (architecture)]] [[gl:Arco (arquitectura)]] [[ko:아치]] [[hi:चाप]] [[hr:Luk (arhitektura)]] [[is:Bogi (byggingarlist)]] [[it:Arco (architettura)]] [[he:קשת (מבנה)]] [[la:Arcus (architectura)]] [[lv:Arka]] [[hu:Boltív]] [[nl:Boog (bouwkunde)]] [[ja:アーチ]] [[no:Bue (arkitektur)]] [[nn:Boge i arkitekturen]] [[nrm:Arche]] [[pl:Łuk (architektura)]] [[pt:Arco (arquitectura)]] [[ru:Арка]] [[simple:Arch]] [[fi:Kaari (rakennustekniikka)]] [[sv:Båge]] [[th:อาร์ช]] [[uk:Арка]] [[zh:拱]]