Dictionary:

arch¹

  (ärch)

(Click to enlarge)

arch1

semicircular arch A. keystone B. voussoirs C. springers D. imposts (Precision Graphics)

1. A structure, especially one of masonry, forming the curved, pointed, or flat upper edge of an open space and supporting the weight above it, as in a bridge or doorway.
2. A structure, such as a freestanding monument, shaped like an inverted U.
3. A curve with the ends down and the middle up: the arch of a raised eyebrow.
4. Anatomy. An organ or structure having a curved or bowlike appearance, especially either of two arched sections of the bony structure of the foot.

1. To provide with an arch: arch a passageway.
2. To cause to form an arch or similar curve.
3. To bend backward: The dancers alternately arched and hunched their backs.
4. To span: “the rude bridge that arched the flood” (Ralph Waldo Emerson).

To form an arch or archlike curve: The high fly ball arched toward the stands.

[Middle English, from Old French arche, from Vulgar Latin *arca, from Latin arcus.]

1. Chief; principal: their arch foe.
2. Mischievous; roguish: an arch glance.

[From ARCH–¹.]

A structure, usually curved, that when subjected to vertical loads causes its two end supports to develop reactions with inwardly directed horizontal components. The designations of the various parts of an arch are given in the illustration. The commonest uses for an arch are as a bridge, supporting a roadway, railroad track, or footpath, and as part of a building, where it provides a large open space unobstructed by columns. Arches are usually built of steel, reinforced concrete, or timber.

An open-spandrel, concrete, fixed-arch bridge.

On the basis of structural behavior, arches are classified as fixed (hingeless), single-hinged, two-hinged, or three-hinged. An arch is considered to be fixed when rotation is prevented at its supports. Reinforced concrete ribs are almost always fixed. For long-span steel structures only fixed solid-rib arches are used. Because of its greater stiffness, the fixed arch is better suited for long spans than hinged arches.

Concrete is relatively weak in tension and shear but strong in compression and is therefore ideal for arch construction. Precast reinforced concrete arches of the three-hinged type have been used in buildings for spans up to 160 ft (49 m).

Steel arches are solid-rib or braced-rib arches. Solid-rib arches usually have two hinges but may be hingeless. The braced-rib arch has a system of diagonal bracing replacing the solid web of the solid-rib arch. The world's longest arch spans are two-hinged arches of the braced-rib type. The spandrel-braced arch is essentially a deck truss with a curved lower chord, the truss being capable of developing horizontal thrust at each support. This type of arch is generally constructed with two or three hinges because of the difficulty of adequately anchoring the skewbacks.

Wood arches may be of the solid-rib or braced-rib type. Solid-rib arches are of laminated construction and can be shaped to almost any required form. Arches are usually built up of nominal 1- or 2-in. (2.5- or 5-cm) material because bending on individual laminations is more readily accomplished. Because of ease in fabrication and erection, most solid-rib arches are of the three-hinged type. This type has been used for spans of more than 200 ft (60 m). The lamella arch has been widely used to provide wide clear spans for gymnasiums and auditoriums. The wood lamella arch is more widely used than its counterpart in steel. The characteristic diamond pattern of lamella construction provides a unique and pleasing appearance. See also Bridge; Buildings; Truss.

The masonry arch can provide structure and beauty, is fireproof, requires comparatively little maintenance, and has a high tolerance for foundation settlement and movement due to other environmental factors. Most arches are curved, but many hectares (acres) of floor in highrise office and public buildings are supported by hollow-tile jack (flat) arches. If a curved arch is wide (dimension normal to span), the arch is referred to as a barrel arch or vault. The vault cross section may have several different shapes. Contiguous vaults may be individual, may intersect, or may cross. A four-part vault is termed quadripartite. Contiguous quadripartite vaults that are supported at the corners by columns are masonry skeletons of large cathedrals.

Stone for masonry skeletons is cut from three classes of rock; igneous (granite, traprock), metamorphic (gneiss, slate, quartzite), and sedimentary (limestone, sandstone). The primary requirements for brick as a structural material are compressive strength and weathering resistance. Hollow clay tiles (terra-cotta) for floor arches are made semiporous in order to improve fire resistance. See also Brick; Metamorphic rocks; Sedimentary rocks.

verb

1. To swerve from a straight line: angle, arc, bend, bow, crook, curve, round, turn. See straight/bent.
2. To incline the body: bend, bow, hump, hunch, scrunch, stoop. See posture.

Definition: principal, superior
Antonyms: inferior

n

Definition: curve
Antonyms: straightness

A structure with a curved outline.

face of the teeth and soldered to the anchor bands.

In coastal geomorphology, an arch is made when two caves occurring on either side of a headland are cut until they meet. Durdle Door, Dorset, is a British example, and arches are common on the coast of the French Pays de Caux. Arches are relatively temporary features of the landscape. Roof falls cut off the seaward end of the arch, which is then left as a stack.

(click to enlarge)
The arch supports a vertical load primarily by axial compression of its wedge-shaped voussoirs. As … (credit: © Merriam-Webster Inc.)

Curved structure that spans the opening between two piers or columns and supports loads from above. The masonry arch provides the stepping stone from the post-and-beam system to the evolution of the vault, and was first widely used by the Romans. Its construction depends on a series of wedge-shaped blocks (voussoirs) set side by side in a semicircular curve or along two intersecting arcs (as in a pointed arch). The central voussoir is called the keystone, and the two points where the arch rests on its supports are known as the spring points. An arch can carry a much greater load than a horizontal beam of the same size and material, because downward pressure forces the voussoirs together instead of apart. The resulting outward thrust must be resisted by the arch's supports. Present-day lightweight monolithic (one-piece) arches of steel, concrete, or laminated wood are highly rigid, and thereby minimize horizontal thrust.

For more information on arch, visit Britannica.com.

A construction that spans an opening; usually curved; often consists of wedge-shaped blocks (voussoirs) having their narrower ends toward the opening. Arches vary in shape, from those that have little or no curvature to those that are acutely pointed. For special types of arches, see acute arch, anse de panier, arrière-voussure, back arch, basket-handle arch, bell arch, blind arch, camber arch, catenary arch, cinquefoil arch, compound arch, cusped arch, diminished arch, discharging arch, Dutch arch, elliptical arch, equilateral arch,

arch: Ex Estrados; In intrados; K keystone; S springers; v voussoirs

In architecture, a curved or pointed opening that spans a doorway, window, or other space.

A structure of bowlike or curved outline.

• a. of aorta — the curving portion between the ascending and descending aorta, giving rise to the brachiocephalic trunk and, in some species, the left common carotid and the left subclavian artery.
• aortic a's — paired vessels that run from the ventral to the dorsal aortae through the branchial arches of fishes and amniote embryos. In mammalian development, arches 1 and 2 disappear; 3 joins the common to become the internal carotid artery; 4 becomes the arch of the aorta and joins the aorta and subclavian artery; 5 disappears; 6 forms the pulmonary arteries and, until birth, the ductus arteriosus.
• arterial a. — one or more arteries that form an anastomotic connection between two more or less parallel tributaries; found commonly around joints and other moveable parts.
• a. arteriosus, arcus arteriosus — a large communicating branch between two arteries.
• branchial a's — four pairs of mesenchymal and later cartilaginous columns in the pharyngeal wall which in fish develop into gills and in mammals become modified into structures of the ear and neck.
• branchial a. derivatives — derivatives of the arches are first arch (mandible, ossicles), second arch (hyoid apparatus, ear ossicles), third arch (hyoid apparatus), fourth arch (laryngeal cartilages).
• costal a. — the rim to the bony thorax formed by the conjoined asternal ribs and their connecting elastic tissue.
• cricoid a. — the slender ventral half of the cricoid cartilage of the larynx. The most caudal of the palpable landmarks of the larynx.
• dental a. — the curving structure formed by the crowns of the teeth in their normal position, or by the residual ridge after loss of the teeth.
• hemal a. — the v- or y-shaped bone borne on the ventral surface of the tail vertebrae of some animals and which protects blood vessels. Called also chevron bone.
• hyoid a. — the second branchial arch.
• ischial a., ischiatic a. — the caudal rim of the pelvis formed by the conjunction of the two ischiae. Called also sciatic arch.
• lumbocostal a. of the diaphragm — the dorsal part of the diaphragm where it crosses the ventral surface of the psoas muscles. Here it is without any attachment and only serous membranes separate the thoracic and peritoneal cavities.
• mandibular a. — the first branchial arch, being the rudiment of the maxillary and mandibular regions.
• neural a. — the dorsal vertebral arch.
• palatal a. — the arch formed by the roof of the mouth from the teeth on one side to those on the other.
• palatoglossal a. — the thick fold of tissue passing from the soft palate to the lateral border of the tongue.
• palatopharyngeal a. — a horizontal fold of pharyngeal mucosa that passes from the soft palate and joins with its opposite fold over the entrance to the esophagus.
• palmar a. — a superficial and a deep vascular arch behind the carpus formed by the conjunction of several arteries of the forearm.
• pulmonary a's — the most caudal of the embryonic aortic arches, which become the pulmonary arteries.
• sciatic a. — ischial arch.
• subcarpal a. — the deep palmar arch, especially of horses.
• superficial dorsal a. — one of the arterial arches in the foot of carnivores.
• supracarpal a. — the superficial palmar arch, especially of horses.
• tendinous a. — a linear arched thickening of fascia that provides attachment for some muscles.
• terminal a. — the union between the medial and lateral palmar digital arteries, which in horses runs through the solar canal within the distal phalanx.
• vertebral a. — the dorsal bony arch of a vertebra, composed of paired laminae and pedicles.
• zygomatic a. — the arch formed by the processes of the zygomatic and temporal bones that is the principal origin of the masseter muscle and is particularly broad and prominent in carnivores.

Tutor's tip: An "ark" (similar to Noah's boat) can make an "arc" (segment of a circle) in the water, but not an "arch" (curved structure over an open space) over the water.

A masonry arch
1. Keystone 2. Voussoir 3. Extrados 4. Impost 5. Intrados 6. Rise 7. Clear span 8. Abutment

An arch is a curved structure capable of spanning a space while supporting significant weight (e.g. a doorway in a stone wall). The arch appeared in Mesopotamia, Indus Valley civilization, Egypt, Assyria, Etruria, and later refined in Ancient Rome. The arch became an important technique in cathedral building and is still used today in some modern structures such as bridges.

History

Arch of the General Staff Building in Palace Square, St Petersburg

The incomplete mausoleum of Adil Shah, Barakaman (Ali Roza-II), which means twelve arches in Urdu

Roman aqueduct supplying Carthage, Tunisia

Arches were used by the Persian, Harappan, Egyptian, Babylonian, Greek and Assyrian civilizations for underground structures such as drains and vaults, but the ancient Romans were the first to use them widely above ground although it is thought that Romans learned it from the Etruscans. The arch has been used in some bridges in China since the Sui dynasty and in tombs since the Han Dynasty.

The so-called Roman arch is semicircular, and built from an odd number of arch bricks (called voussoirs). You need an odd number of bricks for there to be a capstone or keystone. This the topmost stone in the arch. An 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 semicircular arch can be flattened to make an elliptical arch. The Romans used this type of semicircular arch freely in many of their secular structures such as aqueducts, palaces and amphitheaters.

The semicircular arch was followed in Europe by the pointed Gothic arch or ogive, whose centreline more closely followed the forces of compression and which was therefore stronger. This design had been used by the Assyrians as early as 722 BC. The parabolic and catenary arches are now known to be the theoretically strongest forms. A parabolic arch was introduced in the Ponte Santa Trinità, Florence, constructed by the architect Bartolomeo Ammanati from 1567 to 1569. Parabolic arches were introduced in construction by the Spanish architect Antoni Gaudí, who admired the structural system of Gothic style, but for the buttresses, that were designated by him “architectural crutches”. 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 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.^[1] It was used in Spanish Visigothic architecture, Islamic architecture and mudéjar architecture, as in the Great Mosque of Damascus and in later Moorish buildings. It was used for decoration rather than for strength.

Construction

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 voussoirs 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 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 following gallery shows examples of arch forms displayed in roughly the order in which they were developed.

Triangular arch	Round arch or Semi-circular arch	Segmental arch	Unequal round arch or Rampant round arch
Lancet arch	Equilateral pointed arch	Shouldered flat arch	Three-foiled cusped arch
Horseshoe arch	Three-centred arch	Elliptical arch	Inflexed arch
Ogee arch	Reverse ogee arch	Tudor arch	Catenary or Parabolic arch

Technical aspects

Simple arch bridge, China

The arch is significant because, in theory at least, it provides a structure which eliminates tensile stresses in spanning an open space. All the forces are resolved into compressive stresses. This is useful because several of the available building materials such as stone, cast iron and concrete can strongly resist compression but are very weak when tension, shear or torsional 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 walls or dams.

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 reinforcement rods or fibres. (See Arch bridge.)

Related terms and concepts

Other types

The Delicate Arch, a natural arch

The Arc de Triomphe, Paris; a 19th century triumphal arch modelled on the classical 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. Igloos are notable early structures making use of domes.

Natural rock formations may also be referred to as arches. These natural arches 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 is an application of the arch extended horizontally in two dimensions; the groin vault is the intersection of two vaults.

Gallery

The dry stone bridge, so called Porta Rosa (4th century BC), in Elea	Arch of Constantine, Rome, Italy commemorating a victory by Constantine I in 312 AD	The Gateway Arch in Saint Louis, Missouri; a sculpture based on a catenary arch	Doubled round archivolts - Igreja de Nossa Senhora da Assunção, Linhares da Beira, Portugal.
Stonework arches seen in a ruined stonework building - Burg Lippspringe, Germany	Several arches at the Casa Simón Bolívar in Havana, Cuba

References

Wikimedia Commons has media related to:

Arch

• Roth, Leland M (1993). Understanding Architecture: Its Elements History and Meaning. Oxford, UK: Westview Press. ISBN 0-06-430158-3.  pp. 27-8

See also

• Corbelled arch
• Blind arch
• Suspension bridge

External links

• DIYinfo.org's Constructing Brick Arches Wiki - A wiki on how to construct brick arches around the house
• DIYinfo.org's Constructing Timber Framed Arches Wiki - Similar to the brick arches but extra information for timber archesnrm:Arche

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
1.
n. - bue, buespand
v. tr. - krumme, bue, bukke, give bueform
v. intr. - danne bue, beskrive en bue

2.
adj. - skælmsk, drilsk, underfundig

Nederlands (Dutch)
boog, voetholte, schalks, aarts-, buigen, (over) welven, zich welven,

Français (French)
1.
n. - arc, voûte, arche, (Archit) arc, cintre, arcade (sourcilière), cambrure, voûte plantaire
v. tr. - arquer, cambrer
v. intr. - former une voûte, être en forme d'arche, s'arquer

2.
adj. - malicieux, condescendant

Deutsch (German)
1.
n. - Bogen
v. - biegen, sich wölben

2.
adj. - schelmisch

Ελληνική (Greek)
n. - (αρχιτ.) αψίδα, καμάρα, τόξο (αψίδας κτλ.), καμάρα του πέλματος
v. - κυρτώνω/-ομαι, σχηματίζω τόξο, γεφυρώνω, καμπουριάζω, λυγίζω
adj. - ναζιάρικος, τσαχπίνικος, κατεργάρικος
pref. - αρχι-

Italiano (Italian)
curvare, arcuare, arcuarsi, arco, volta, birichino, superiore

Português (Portuguese)
n. - arco (m) (Arquit.), arcada (f), abóbada (f) (Arquit.), peito (m) do pé (Anat.)
v. - arquear(-se)
adj. - brejeiro, travesso
pref. - arqui-

idioms:

• triumphal arch    arco (m) do triunfo

Русский (Russian)
перекрывать сводом, выгибать, изгибать, арка, игривый, лукавый, хитрый

idioms:

• triumphal arch    триумфальная арка

Español (Spanish)
1.
n. - arco, grande, malicioso
v. tr. - doblar, arquear, combar, curvar
v. intr. - arquearse, doblarse, combarse, curvarse, formar un arco

2.
adj. - doblado, combado, arqueado, curvado

Svenska (Swedish)
n. - valv
v. - välva, kröka
adj. - skälmaktig, illmarig
pref. - ärke-, ursprunglig

中文（简体） (Chinese (Simplified))
1. 拱门, 弓形, 使成弧形, 拱起, 使成弓形, 呈拱形覆盖, 形成弧形, 呈弧形移动

2. 调皮的, 淘气的, 为首的, 主要的

中文（繁體） (Chinese (Traditional))
1.
adj. - 調皮的, 淘氣的, 為首的, 主要的

2.
n. - 拱門, 弓形
v. tr. - 使成弧形, 拱起, 使成弓形, 呈拱形覆蓋
v. intr. - 形成弧形, 呈弧形移動

한국어 (Korean)
1.
n. - 아치, 궁형, 장심
v. tr. - ~애 아치를 놓다[을 아치 모양으로 만들다]
v. intr. - 아치(활) 모양으로 되다

2.
adj. - 중요한, 간교한, 짓궂은

日本語 (Japanese)
n. - アーチ, アーチ門, アーチ状のもの, 土踏まず
v. - アーチ形にする, アーチ形になる
adj. - いたずらっぽい, ずるそうな, 人を見下す

idioms:

• triumphal arch    凱旋門

العربيه (Arabic)
‏(الاسم) قنطره, قوس, , قوس, القدم (فعل) يقوس, , يتقوس, , رئسي (صفه) شي شبيه بالقنطره, مدخل أو ممر تحت قنطره (بادئه الكلمه) قنطره‏

עברית (Hebrew)
n. - ‮קשת, קימור, קמרון, שער מקומר‬
v. tr. - ‮קימר, קישת, גבנן‬
v. intr. - ‮התקמר‬
adj. - ‮ערמומי, ממולח, שובבי, ראשי‬

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