Architecture / Structure / Arch

structure / arch / arcade

• arcade: A series of arches supported by columns or piers.
• arcaded attic story: A series of arches supported by columns or piers located immediately below the roof and above the principal floors of a building in the attic space.
• arcaded gallery: A roofed promenade along the exterior wall of a building punctuated by a series of arches.
• arcaded loggia: A pillared gallery or porch open on at least one side. Usually an integral part of the building’s mass rather than an appended porch.
• arcading: A passageway with a roof supported by arched columns.
• arcature: A miniature arcade, such as an arched balustrade.
• arcuatio: In ancient Rome, a structure formed by means of arches or arcades and employed to support a construction of any kind, such as an aqueduct.
• blank arcade: Same as blind arcade.
• blind arcade: A decorative row of arches applied to a wall as a decorative element, especially in Romanesque buildings.
• interlaced arch: Also see interlacing arcade.
• interlaced arches: Also see interlacing arcade.
• interlacing arcade: Arches resting on alternate supports in one row, the arches overlapping in series where they cross. Also see intersecting arcade.
• intersecting arcade: Arches resting on alternate supports in one row, the arches meeting on one plane at the crossings. Also see interlacing arcade.
• nave arcade: The open arcade between the central and side aisles.
• respond: A half-pier or pillar at the end of an arcade.
• riwaq: A colonnaded or arcaded hall of a mosque.
• surface arcade: Also see blind arcade.
• tribelon: A triple arcade which connects the nave with the narthex.
• wall arcade: A blind arcade used as an ornamental dressing to a wall.
• zaguan: In Spanish Colonial architecture, a covered passage connecting the patio to the street.

structure / arch / arch

• arc dobleau: An arch forming a projection upon the main soffit or intrados of an arch, in section similar to that of a pilaster and its background.
• arch: A form of construction, usually of masonry, in which a number of units span an opening by carrying the downward thrust laterally to the next unit and finally to the abutments or vertical supports. Unusually further described by its intrados outline, as round, elliptical, pointed, trefoil, etc.
• arcuate: Composed of arches.
• arcuated: A structural form composed of numerous arches, in contrast to trabeated.
• arcuation: The employment of arches. 2. A series or system of arches.
• arcus: In ancient Roman construction, an arch. 2. A triumphal arch.
• concameration: An arch or vault. 2. An apartment; a chamber.
• imbow: To arch over.
• imbowment: An arch or vault.
• acute arch: A sharply pointed two-centered arch whose centers of curvature are farther apart than the width of the arch.
• arcus presbyterii: In medieval architecture, the arch marking the upper boundary of the tribune.
• back arch: An arch whose interior surface is different behind the face of a wall that it is at the face; a usual mode of construction in medieval buildings and in French architecture of the 17th and 18th century; an arriere-voussure or rear arch.
• barrel arch: An arch formed of a curved solid plate or slab, as contrasted with one formed with individual curved members or ribs.
• basket arch: An elliptical arch suggesting the shape of a basket handle.
• baskethandle : An elliptical arch suggesting the shape of a basket handle.
• basket-handle arch: An elliptical arch suggesting the shape of a basket handle.
• basket-handle-arch: An elliptical arch suggesting the shape of a basket handle.
• anse de panier: A basket-handle arch.
• anse-de-panier: Also see basket handle.
• basket handle: Also see basket handle.
• blind arch: An arch that does not contain an opening for a window or door but is set against or indented within a wall.
• blunt arch: An arch rising to a slight point, struck from two centers within the arch.
• braced arch: An openwork truss in the form of an arch.
• brick arch: An arch composed of individual brick units set on end.
• broken arch: A form of segmental arch in which the center of the arch is omitted and is replaced by a decorative feature; usually applied to a wall above the entablature over a door or window.
• catenary arch: An arch which takes the form of an inverted catenary.
• chamber arch: A type of arch.
• chancel arch: An arch which, in many churches, marks the separation of the chancel or sanctuary from the nave or body of the church.
• arcus choralis: Also see arcus ecclesiae, arcus presbyterii, arcus triumphalis.
• ch’uan: In traditional Chinese construction, an arch.
• fa ch’uang: In traditional Chinese architecture, a masonry arch.
• cinquefoil arch: Decorative element representing a five-leafed form.
• circular arch : Cinquefoil tracery at the apex of a window.
• circular arch types: Cinquefoil tracery at the apex of a window.
• three centered arch: A type of circular arch.
• three-centred arch: A type of circular arch.
• composite arch: An arch whose curves are struck from four centers, as in English Perpendicular Gothic; a mixed arch.
• compound arch: An arched entry formed by a series of concentric and progressively smaller arches set within one another.
• chia ch’uan: In Chinese architecture, a corbel arch.
• corbel arch: An arch-like construction composed of courses of masonry advancing inward as they rise on both sides of a wall opening.
• corbeled arch: A type of pointed arch.
• corbelled arch: A type of pointed arch.
• kokoshniki: In early Russian architecture, a series of corbeled arches (usually one of two or three tiers, one above the other); especially used around the drum supporting a cupola. 2. Any similar decorative feature.
• counter arch: An arch used to counteract the thrust of another arch.
• crescent arch: Also see horseshoe arch.
• crocket arch: An arch in which the intrados forms three or five foils.
• cusped arch: An arch which has cusps or foliations worked on the intrados.
• foiled arch: Same as cusped arch.
• lobed arch: A cusped arch.
• cycloidal arch: An arch whose intrados forms a cycloid.
• depressed: See arch.
• depressed arch: A drop arch. 2. A flat headed opening with the angles round off into segments of circles; frequently used in the perpendicular style.
• depressed three-centred arch: A type of arch form.
• diaphragm: See arch. 2. A relatively thin, rigid structural member capable of withstanding shear when loaded in a direction parallel to its plane.
• diaphragm arch: A transverse arch across the nave of a church.
• diaphram arch: A transverse, wall-bearing arch that divides a vault or a ceiling into compartments, providing a kind of firebreak.
• discontinuous diaphragm: A horizontal diaphragm having a large cutout or open area, or a stiffness significantly less than that of the story above or below.
• horizontal diaphragm: A rigid floor or roof plane acting as a thin, deep beam in transferring lateral forces to vertical shear walls, braced frames, or rigid frames.
• diminished: For diminished arch, see arch. 2. In a sash-window, a diminished bar is a glazing-bar molded or shaped to present a finer, thinner appearance inside a room than it would appear if unshaped. 3. Diminishing or graduated courses are layers or rows of slates that are of the same length in each course, but diminishing in height with each course from eaves to ridge.
• diminished arch: Also see skeen arch, skene arch.
• discharging: See arch.
• discharging arch: An arch built above another structural member to relieve its load. Also called relieving arch.
• arc-doubleau: An arch forming a projection upon the main soffit or intrados of an arch, in section similar to that of a pilaster and its background.
• Dutch arch: One divided horizontally in two leaves which operate independently or, locked together, as one.
• arcus ecclesiae: In medieval architecture, the arch dividing nave from choir.
• elliptical arch: An arch whose shape is generated by a point moving in such a way that the sums of its distances from two fixed points, the foci, is a constant.
• three-centered arch: An arch approximating elliptical form in which the intrados is a combination of three arcs of circles, one centered between a symmetrically disposed pair.
• equilateral: See arch. 2. An equilateral roof has 60 degree pitches, and thus in section the timbers form an equilateral triangle.
• equilateral arch: A pointed arch having two centers and radii equal to the span.
• equilateral pointed arch: A pointed arch having two centers and radii equal to the span.
• three-pointed arch: See equilateral arch.
• extradosed arch: One which has the extrados clearly marked, as a curve exactly or nearly parallel to the intrados; has a well-marked archivolt.
• false arch: One having the appearance of an arch, though not of arch construction, as a corbel arch.
• five-centered arch: An arch whose intrados is struck from five centers.
• fixed arch: A fixed frame structure having an arched form.
• flat arch: An arch with a flat intrados (underside). The term soldier arch is usually reserved for a flat arch built of soldiers (bricks laid vertically).
• floor arch: A structural vault form supported by longitudinal beams.
• Florentine arch: An arch whose extrados is not concentric with its intrados and whose voussoirs are therefore longer at the crown than at the springing; common in the region of Florence in the late Middle Ages and early Renaissance.
• four centered arch: A shallow pointed arch formed by four circular arcs.
• four-centered: See arch.
• four-centered arch: A shallow pointed arch struck from four centers, as in a Tudor arch.
• four-centered pointed arch: See Tudor arch.
• pseudo four-centred: A type of pointed arch.
• French arch: Also see flat arch.
• funicular arch: An arch shaped to develop only axial compression under a given loading. This shape may be found by inverting the funicular shape for a cable carrying a similar loading pattern. As with any funicular structure, a funicular arch is subject to bending if the load pattern changes. An inverted catenary is the funicular shape for an arch carrying a vertical load uniformly distributed along the length of the arch axis. The parabola is the funicular shape for an arch carrying a vertical load uniformly distributed over its horizontal projection.
• gauged arch: An arch of wedge-shaped bricks which have been shaped so that the joints radiate from a common center.
• Gothic arch: The Gothic period in Europe extended from 1200 through 1600 in many areas. The style was characterized by the lancet arch as well as many other arch types. Each country has a different defining Gothic arch style.
• hance: The half-arch joining a lintel to a jamb. 2. A haunch.
• hance arch: Same as hanse arch.
• hanse: Also see hance.
• hanse arch: Also see haunch arch.
• haunch arch: See hanse arch.
• Arabic arch: A horseshoe arch.
• chandrashala: The circular or horseshoe arch that decorates many Indian cave temples and shrines.
• horseshoe arch: An arch shaped like a horseshoe; common in Islamic architecture. Appears in Exotic Revival houses in the 1850s and 1880s. Also called a Syrian arch.
• pointed horseshoe arch: A type of arch.
• round horseshoe arch: A type of arch.
• imperfect arch: A diminished arch.
• Indian arch: A pointed arch whose lower portion is a curve greater than a semicircle.
• inflected arch: Also see inverted arch.
• interlacing arch: Or, more properly, interlacing archivolt, one of a series in which interlacing is simulated.
• interrupted arch: A segmental pediment whose center has been omitted, often to accommodate an ornament.
• inverted arch: An arch in which the keystone is the lowest point.
• Islamic arch: Also see horseshoe arch.
• jack arch: A structural element that provides support over an opening in a masonry wall (i.e., made of brick or stone). Jack arches are not actually arch-shaped, but are, instead, flat, and made of individual wedge-shaped bricks or stones held in place through compression.
• drop arch: A form of the lancet arch in which the centers of the two halves are located within the span.
• lancet: A sharply pointed Gothic arch or window.
• lancet arch: A pointed arch having two centers and radii greater than the span, also typical of Gothic architecture.
• lanceted: Having a lancet window or arch.
• masonry arch: An arch constructed of individual stone or brick voussoirs.
• Maya arch: A corbeled arch of triangular shape common in the buildings of the Maya Indians of Yucatan.
• Mayan arch: Also see triangular arch.
• memorial arch: An arch commemorating a person or event, popular during the Roman Empire, and again at the time of Napoleon and later. If the event is a military one, it is also called a triumphal arch.
• miter arch: Two straight blocks of stone set diagonally over an opening, the upper ends resting against each other.
• mitre arch: Two straight blocks of stone set diagonally over an opening, the upper ends resting against each other.
• mixed arch: A three- or four-centered arch; a composite arch.
• mixtilinear arch: In Moorish and Spanish architecture, an arch composed of various geometric shapes.
• Moorish arch: An arch having an intrados that widens above the springing before narrowing to a rounded crown.
• multicentered arch: An arch having a shape composed of a series of circular arcs with different radii, giving an approximation to an ellipse. These arcs are symmetrically disposed about a vertical axis and occur in odd numbers.
• ping ch’uan: In Chinese architecture, a multi-centered arch.
• multi-foil arch: An arch of more than five arcs.
• mural arch: An arch in a wall which was constructed in the plane of the meridian; used for attachment of astronomical instruments in the Middle Ages.
• oblique arch: Same as skew arch.
• obtuse angle arch: A type of pointed arch, formed by arcs of circles which intersect at the apex; the centers of the circles are nearer together than the width of the arch.
• contrasted arch: An ogee arch.
• keel arch: Also see ogee arch.
• keel-arch: Ogee arch.
• ogee arch: A pointed arch, each haunch of which is a double curve with the concave side uppermost.
• one-centered arch: Any arch struck from a single center, such as a round, segmental, or horseshoe arch.
• pai-lou: A monumental Chinese arch or gateway with one, three, or five openings; erected at the entrance to a palace, tomb, or processional way. Usually built of stone in imitation of wood construction.
• parabolic arch: An arch similar to a three-centered arch but whose intrados is parabolic, with a vertical axis.
• party arch: An arch on the line separating the property of two owners.
• peak arch: A pointed arch.
• pediment arch: Also see miter arch.
• pier arch: An arch resting on piers, especially one along a nave arcade.
• ogival: Having a pointed arch or vault, as in the nave of a Gothic church.
• pointed arch: An arch composed of two curves with radii equal to its span (width).
• pointed Saracenic arch: A type of arch.
• pointed segmental arch: A type of arch.
• pointed trifoliated arch: A type of arch.
• tierce point: The pointed arch.
• archway: A passage through or under an arch, especially when long, as under a barrel vault.
• Queen Anne arch: An arch over the triple opening of the so-called Venetian or Palladian window, flat over the narrow side lights, round over the larger central opening.
• Queen-Anne arch: Arch formed of a central semicircular arch flanked by two ‘flat’ arches constructed of brick rubbers set over tall thin side-lights on either side of a wider semi-circular-headed window, a variation on the Palladian or Venetian window known as a serliana… It is commoner in the Georgian period than in the Queen Anne.
• raking arch: Same as rampant arch.
• rampant: See arch.
• rampant arch: An arch with one abutment higher than the other.
• arriere-voussure: Also see rear arch.
• rear arch: An inner arch of an opening which is smaller in size than the external arch of the opening and may be different in shape. 2. See arriere-voussure.
• rere-arch: Also see rear arch.
• recessed arch: An arch with a shorter radius set within another of the same shape.
• relieving arch: An arch embedded in a wall; used to relieve the section below it of weight from above. A relieving arch is often found over a lintel or a flat arch.
• ribbed arch: An arch composed of individual curved members or ribs.
• Richardsonian arch: Round arches over door and window openings, a heaviness of appearance created by rock faced stonework, as in the Richardsonian Romanesque style.
• rigid arch: An arched structure of timber, steel, or reinforced concrete, constructed as a rigid body capable of carrying bending stresses.
• rising arch: An arch having a springing line which is not horizontal.
• Roman arch: Round arch.
• rough arch: Same as discharging arch; built with rectangular bricks and wedge-shaped mortar joints.
• round arched: Describing an element, typically a window or a door, whose head takes the shape of a half-circle.
• rowlock arch: An arch wherein the bricks or small voussoirs are arranged in separate concentric rings.
• rubble arch: See rustic arch.
• rustic arch: Also see rubble arch.
• safety arch: A discharging arch.
• scheme arch: An arch which forms part of a circle which is less than a semicircle.
• scoinson arch: An arch carrying a part only of the thickness of a wall, as behind a window frame; or one of slight reveal forming a flat niche or recessed panel.
• sconcheon arch: Also see scoinson arch.
• segmental arch: A partial arch form usually made of brick and located over window or door openings.
• segmental relieving arch: A partial arch form usually made of brick and located over window or door openings.
• bell arch: Semicircular arch supported on quarter-round corbels.
• compass-headed arch: A semicircular arch.
• full-centred: Semicircular; said of an arch. Obviously a translation (partially erroneous) of the French term plein cintre.
• round arch: A semicircular arch.
• surmounted arch: A semicircular stilted arch.
• Syrian arch: A type of semicircular arch that has very low supports, with the result that the distance from the impost to the level of the crown of the arch is greater than the height of the impost from the ground. It is so called because it was used in the Early Christian churches of Syria, in the 5th and 6th centuries.
• chen ch’uan: In Chinese construction, a semi-circular arch or triangular arch.
• semi circular arch: An arch in the form of a half circle.
• semi circular stilted arch: A type of arch.
• semicircular arch: An arch in the form of a half circle.
• t’ung ch’uan: In Chinese architecture, a semi-circular arch.
• semielliptical arch: Strictly, an arch whose intrados is half an ellipse; in practice the term usually denotes a three- or five-centered arch.
• shouldered arch: A lintel carried on corbels at either end; a squareheaded trefoil arch.
• skeen arch: A diminished arch.
• skene arch: A diminished arch.
• skew arch: An arch having jambs not at right angles to its face.
• skewback: A sloping surface that serves as a support for the end of an arch.
• sluing arch: A splayed arch.
• soldier arch: A flat arch in brick, having the stretchers (long sides) of the uncut bricks set vertically.
• splayed arch: An arch opening which has a larger radius in front than at the back.
• squinch arch: See squinch.
• stepped arch: An arch in which some or all of the voussoirs have their outer ends cut square to fit the horizontal courses of the wall to the sides of the arch.
• stilted: Raised higher than is normal, or usually, or seeming to be so raised, a term almost wholly limited to the arch, which is said to be stilted when the curve does not spring at or close to the top of the capital or of the molded or otherwise strongly marked impost…
• stilted arch: An arch whose curve begins above the level of the imposts.
• stilted-arch: An arch in which the springing line is higher than the impost instead of being at the same height.
• straight arch: A flat arch.
• strainer arch: Remedial arches inserted across a nave or aisle to prevent subsidence. The best known examples are that the crossing of Wells Cathedral, England.
• subarch: One of two or more minor arches beneath and enclosed by an outer arch.
• surbased arch: An arch whose rise is less than half the span.
• surmounted: See arch. 2. Element placed over another part, such as a door-case surmounted by a sopraporta.
• arctuated lintel: Same as Syrian arch.
• pseudo three-centred: A type of pointed arch.
• three-hinged arch: An arch with hinges at the two supports and at the crown.
• three-pinned arch: Also see three-hinged arch.
• through arch: Any arch which is set in a thick, heavy wall.
• trabeated arch: An arch pointed at the top formed by voussoirs whose inside radius is greater than one-half the span of the arch.
• pointed trefoil arch: A type of arch.
• round trefoil arch: A type of circular arch.
• trefoil arch: Composed of three foils or leaves, a trefoil can be a pattern over a window or an arch design. A trefoil pattern is most frequently found in Gothic designs.
• trilobe arch: Also see trefoil arch.
• chen huan: In Chinese architecture, a triangular arch.
• triangular arch: A type of pointed arch.
• round trifoliated arch: A type of circular arch.
• brick trimmer: Same as trimmer arch.
• trimmer arch: A flat or segmental arch between chimney and a trimmer beam for the support of a hearth.
• arc de triomphe: Also see triumphal arch.
• arcus trimphalis: Also see triumphal arch.
• arcus triumphalis: Also see arcus ecclesiae, arcus presbyterii, arcus triumphalis.
• trimuphal arch: A large arched structure commemorating a national victory.
• triumphal arch: An arch commemorating the return of a victorious army, usually in the line of march during its triumphal procession. Also see memorial arch.
• trumpet arch: A conically shaped quinch.
• trumpet-arch: See arch.
• Tudor arch: A low, wide, pointed arch common in the architecture of Tudor England.
• twin archway: An opening having two archways side by side.
• two-centered arch: An arch struck from two centers, resulting in a pointed arch. Also see equilateral arch.
• two-hinged arch: An arch with hinges at the supports at both ends.
• urns: Round arches.
• U-shaped arches: Round arches.
• Venetian arch: A pointed arch in which the intrados and extrados are farther apart at the peak than at the springing line.
• arc formeret: The wall arch or wall rib, or the corresponding rib coming next to the arcade between nave and aisle, as in Gothic vaulting.
• Caernarfon: Welsh arch.
• Caernarvon arch: Also see Carnarvon arch.
• Carnarvon arch: A lintel supported on corbels.
• Welsh: See arch.

structure / arch / centring

• arch center: Formwork to support the voussoirs of an arch during construction.
• camber piece: A slightly curved wood board used as a support in laying a brick arch having a small rise.
• centering: The temporary support of masonry under construction, as under an arch or under poured concrete.
• centring: A timber framework or mold, upon which the masonry of an arch or vault is supported until the key is placed which renders it self-supporting…
• lag: In a centring composed of two or more parallel ribs, a cross piece connecting such ribs and supporting the voussoirs. Usually in the collective form lagging.
• turn: To lay up, as an arch, inn brick or stone on a temporary centring.
• turning piece: A piece of board cut to a curve to guide the mason in turning any small arch for which no centring is required.
• camber arch: A flat arch with a very slight upward curve in the intrados and sometimes also in the extrados.
• camber slip: A slightly curved wood board used as a support in laying a brick arch having a small rise.

structure / arch / molding

• archivolt: An architrave molding when it follows the line of an arch.
• arcs dobleaux: Also see arch band.
• alfiz: A rectangular molding which frames a horseshoe arch; typical in Moorish architecture.
• arch ring: In an arched structure, the curved member that sustains the principal load.
• ring stone: One of the stones of an arch which show on the face of the wall, or the end of the arch; one of the voussoirs of the face forming the archivolt.

structure / arch / part

• albanega: In Islamic architecture, a spandrel formed between a horseshoe arch and the rectangular frame around the arch.
• arc en tiers point: In French, the point where the two determining arcs of a pointed arch meet, the apex. The term means originally the third or culminating point of a triangle.
• arch action: The manner in which an arch transforms the vertical forces of a supported load into inclined components and transmits them to abutments on either side of the archway.
• arch axis: The median line of an arched structure.
• crown: The top of an arch or vault. Also, any uppermost or terminal feature in architecture. 2. The leaves and living branches of a tree.
• extrados: The outermost curve of an arch or vault.
• haunch: The part of an arch where the lateral thrust is strongest. 2. The part of a beam that is thickened or deepened to develop greater moment resistance. The efficiency of a beam can be increased by shaping its length in response to the moment and shear values which typically vary along its longitudinal axis.
• intrados: The inner curve of face of an arch or vault forming the concave underside.
• line of thrust: The set of resultants of thrust and weight each part of an arch imposes on the next lower one. For bending to be eliminated throughout an arch, the line of thrust must coincide with the arch axis.
• pitch of an arch: The versed sine, or height, from the springing line to the highest part of the soffit or intrados.
• shoot: A thrust of an arch. 2. Same as chute. 3. In carpentry, to dress an edge; especially to trim two adjoining edges with great care, so as to make a close joint.
• spring line: The point at which an arch unites with its support.
• thrust: The outward force exerted by an arch or a vault that must be counterbalanced by buttresses.
• tiers point: In French, the point where the two determining arcs of a pointed arch meet, the apex. The term means originally the third or culminating point of a triangle.

structure / arch / pier

• piers: One of the square pillars supporting an arch; the solid mass between two openings in a building.

structure / arch / shaft

• edge shafts: Shafts which sustain arches, united by their sides and back to the nearest wall or arch, so they appear to support their edge only; abundantly used in Norman architecture.

structure / arch / stone

• • banded impost: In medieval architecture, an impost with horizontal moldings, the section of the molding of the arch above being similar to that of the shaft below.
  • continuous impost: In Gothic architecture, the moldings of an arch when carried down to the floor without interruption or anything to mark the impost point.
  • coussinet: The stone which is placed on the impost of a pier to receive the first stone of an arch. 2. The part of the front of an Ionic capital between the abacus and echinus.
  • discontinuous impost: A shafted impost, where the arch moldings are different from the moldings of the pier from which the arch springs.
  • dosseret: Also see impost block.
  • impost: The molding of a pier at the springing of an arch.
  • impost return: Where the impost of an arch turns inwards beneath the arch.
  • shafted impost: In medieval architecture, an impost with horizontal moldings, the section of the moldings of the arch above the impost being different from that of the shaft below it.
  • agrafe: A decorative central keystone in an arch, often carved with a human face, cartouche or floral design.
  • agraffe: A decorative central keystone in an arch, often carved with a human face, cartouche or floral design.
  • clavel: Also see clavis.
  • clavis: A keystone of an arch. 2. A mantelpiece. See clavel.
  • double keystone: A keystone that appears to be composed of two plain keystones of varying size, superimposed.
  • headwork: The heads and other ornaments on the keystone of an arch.
  • key block: Center stone in a masonry arch.
  • key console : A console which acts as the keystone of an arch.
  • keystone: Center stone in a masonry arch.
  • mensole: Also see keystone.
  • nodus: In ancient Roman construction, a keystone, or a boss in vaulting.
  • sagitta: The keystone of an arch.
  • Welsh arch: A keystone lintel.
  • kneestone: The stone that decorates the bottom of the spring of an arch. This can be plain as in the example from Hadrian’s Villa or ornate as in the kneestones found in the Loire Valley and other parts of France, Italy, Spain, and England.
  • screwback: Part of a segmental arch.
  • arch solid: One of the masses or pieces of material which, generally more or less wedge-shaped, mutually prevent one another from falling; a voussoir.
  • sommering: Skew-back, or the radiating joint between the voussoirs of an arch.
  • abutment: The solid mass from which an arch springs. 2. A structure for anchoring the reinforcing tendons in the pretensioning of a concrete member.
  • abutment-piece: Cill or sole-plate.
  • butment: Also see abutment.
  • spring: The point at which the arch rises from its support or the point at which the arch enters the radius.
  • springer: The first voussoir resting on the impost of an arch.
  • springers: The stones supporting the arc of an arch.
  • springing: Also see spring.
  • arch stone: Same as voussoir.
  • key up: To raise slightly a structure built of, or secured by, keys, by forcing the keys into the prepared spaces. Thus, in an arch, the last voussoir, serving as a key, may be shaped slightly too large and then be driven into place, by which process the entire arch ring is crowned up higher, even to the extent of raising it entirely from the centering. A similar operation is frequently performed at the base of a settled wall which is to be underpinned.
  • voussoir: The wedge-shaped stone or brick used to form an arch or vault.

Also see Architecture index.