Voussoir in the context of "Portal (architecture)"

In architecture, a vault (French voûte, from Italian volta) is a self-supporting arched form, usually of stone or brick, serving to cover a space with a ceiling or roof. As in building an arch, a temporary support is needed while rings of voussoirs are constructed and the rings placed in position. Until the topmost voussoir, the keystone, is positioned, the vault is not self-supporting. Where timber is easily obtained, this temporary support is provided by centering consisting of a framed truss with a semicircular or segmental head, which supports the voussoirs until the ring of the whole arch is completed.

The Mycenaeans (ca. 1800–1050 BC) were known for their tholos tombs, also called beehive tombs, which were underground structures with conical vaults. This type of vault is one of the earliest evidences of curved brick architecture without the use of stone arches, and its construction represented an innovative technique for covering circular spaces.

Centring, centre, centering, or center is a type of falsework: the temporary structure upon which the stones of an arch or vault are laid during construction. Until the keystone is inserted an arch has no strength and needs the centring to keep the voussoirs in their correct relative positions. A simple centring without a truss is called a common centring. A cross piece connecting centring frames is called a lag or bolst.

Centring is normally made of wood timbers, a relatively straightforward structure in a simple arch or vault; but with more complex shapes involving double curvature, such as a dome or the bottle-shaped flue in a Norman-period kitchen, clay or sand bound by a weak lime mortar would be used. Shaping could be done by eye, perhaps with the help of a template, then stones or bricks laid against it. On larger works like a 19th-century pottery kiln this was impractical. The structure would be built round a post acting as a datum, and each course of stonework would be set at a distance from the datum.

The Eurymedon Bridge (Turkish: Oluk Köprü) is a Roman bridge over the river Eurymedon (modern Köprüçay River) near Selge in Pisidia in southern Turkey. It is part of the road winding up from the coastal region Pamphylia to the Pisidian hinterland. Located 5 km north of the village Beşkonak in a sparsely settled area, the bridge crosses the Eurymedon high above the valley bottom.

The excellently preserved structure is 14 m long and 3.5 m wide (with a roadway of 2.5 m). The clear span of its single arch is c. 7 m, the thickness of its voussoirs, which were set without the use of mortar, 60 cm. The building technique and the sturdy stonework point to a construction date in the 2nd century AD, a time when Selge was flourishing.

A corbel arch (or corbeled / corbelled arch) is an arch-like construction method that uses the architectural technique of corbeling to span a space or void in a structure, such as an entranceway in a wall or as the span of a bridge. A corbel vault uses this technique to support the superstructure of a building's roof.

A corbel arch is constructed by offsetting successive horizontal courses of stone (or brick) beginning at the springline of the walls (the point at which the walls break off from verticality to form an arc toward the apex at the archway's center) so that they project towards the archway's center from each supporting side, until the courses meet at the apex of the archway (often the last gap is bridged with a flat stone). For a corbeled vault covering, the technique is extended in three dimensions along the lengths of two opposing walls.