halfarches

A halfarch, also known as a quoin or corbel arch, is a semicircular or segmental arch that is built into a wall or pier. Unlike a full arch that spans an opening, a halfarch projects outwards from a supporting structure, often serving as a decorative element or a structural support for a projecting element above. They are typically constructed from stone, brick, or concrete.

The term "halfarch" can sometimes be used loosely. In a strictly architectural sense, it refers to a structure that is essentially a portion of an arch, resting on one side against a solid mass and projecting outwards. This contrasts with a relieving arch, which is a full arch built above an opening to distribute weight.

Historically, halfarches have been employed in various architectural styles. They can be found in medieval fortresses, bridges, and domestic buildings. In bridge construction, halfarches are often used in the spandrels of larger arches to reduce the overall weight of the structure and provide additional support. They can also be used to create decorative niches or as supports for balconies or corbels.

Modern applications of halfarches are less common but can still be seen in contemporary architecture, often for aesthetic purposes or as a means to support cantilevered elements in a visually interesting way. The construction requires careful consideration of the load-bearing capabilities of the supporting wall or pier to ensure stability.