Arch
**Basic Concepts and History of Arches:**
– An arch is a curved vertical structure used for support or decoration.
– Arches have been utilized since the fourth millennium BC.
– They can be horizontal, like arch dams, and are often used as supports for vaults.
**Terminology and Components of Arches:**
– A true arch is load-bearing and held together by compression.
– Components of a masonry arch include keystone, voussoir, and extrados.
– Terms like false arch, intrados, and archivolt are essential in understanding arch structures.
**Arch Action and Construction Techniques:**
– A true arch resolves vertical loads into horizontal and vertical reactions.
– Modern arch construction uses ties to relieve horizontal thrust.
– Counter-arches were traditionally used to counteract horizontal forces.
– New construction materials have made arches lighter and less reliant on heavy abutments.
**Shapes and Classifications of Arches:**
– Arches can be classified by their intrados shape, number of circle segments, and construction material.
– Shapes of arches can be rounded, pointed, or parabolic.
– Classification includes brick arches, stone arches, and structural classifications based on movable joints.
**Specific Arch Shapes and Examples:**
– Rounded arches include semicircular, segmental, basket-handle, and horseshoe arches.
– Pointed arches consist of two or more circle segments culminating in a point.
– Examples of arch shapes are found in various architectural styles like Roman, Islamic, and Gothic.
An arch is a curved vertical structure spanning an open space underneath it. Arch can either support the load above it or perform a purely decorative role. The arch dates back to fourth millennium BC, but became popular only after its adoption by the Romans in the 4th century BC.
Arch-like structures can be horizontal, like an arch dam that withstands the horizontal hydrostatic pressure load. Arches are normally used as supports for many types of vaults, with the barrel vault in particular being a continuous arch. Extensive use of arches and vaults characterizes an arcuated construction, as opposed to the trabeated system, where, like in the architectures of ancient Greece, China, and Japan (as well as the modern steel-framed technique), posts and beams dominate.
Arches had several advantages over the lintel, especially in the masonry construction: with the same amount of material it can have larger span, carry more weight, and can be made from smaller and thus more manageable pieces. Their role in construction was diminished in the middle of the 19th century with introduction of the wrought iron (and later steel): the high tensile strength of these new materials made long lintels possible.