buttress

buttress,

mass of masonry built against a wall to strengthen it. It is especially necessary when a vault or an arch places a heavy load or thrust on one part of a wall. In the case of a wall carrying the uniform load of a floor or roof, it is more economical to buttress it at certain intervals than to make the entire wall thicker. Even when a wall carries no load, it is usually buttressed rather than uniformly thickened. For a load-bearing brick wall more than 8 ft (2 m) high a buttress is used every 20 ft (6 m). The decorative possibilities of the buttress were discovered in the ancient temples at Abu Shahrein in Mesopotamia (3500–3000 B.C.), where they were used both as utilitarian and decorative forms. The Romans employed buttresses, which sometimes projected from the exteriors of the walls and were then left as mere piles of masonry, without architectural treatment. But in the large structures, such as basilicas and baths, the buttresses that received the thrusts from the main vaulting were confined to the interior of the building, where they served also as partition walls. The basilica of Constantine in Rome (A.D. 312) exemplifies this arrangement. In the medieval church, the groined vaults, concentrating their great lateral thrusts at points along the exterior walls, required buttresses as an essential element to achieve stability. Beginning with Romanesque architecture about A.D. 1000, a steady evolution of buttresses can be traced, from the simple, slightly projecting piers of the 11th cent. to the bold and complex Gothic examples of the 13th, 14th, and 15th cent. Builders in England, Germany, and N France achieved striking architectural effects. They devised the flying buttress, an arch of masonry abutting against the wall of the nave; the thrust of the nave vault could thus be received and transferred to the vertical buttress built against the outside walls of the side aisles. These flying arches, at first concealed beneath the roofs, began to be exposed outside the roofs in the mid-12th cent. Later they were enriched with gables, stone tracery, and sculpture and were topped with pinnacles to give them extra weight. They constitute, especially in such French cathedrals as Amiens, Beauvais, and Notre-Dame de Paris, the true expression of the elasticity and equilibrium which were the basic principles of the Gothic structural system.

Buttress

An exterior mass of masonry projecting from the wall to absorb the lateral thrusts from roof vaults; either unbroken in their height or broken into stages, with a successive reduction in their projection and width. The offsets dividing these stages are generally sloped at a very acute angle. They terminate at the top with a plain slope ending at the wall or with a triangular pediment.

angle buttress

One of the two buttresses at right angles to each other; forming the corner of a structure.

diagonal buttress

A buttress that bisects the 270-degree angle at the outside corner of a building.

flying buttress

A characteristic feature of Gothic construction in which the lateral thrusts of a roof or vault are carried by a segmental masonry arch, usually sloping, to a solid pier or support that is sufficiently massive to receive the thrust.

Buttress

 

a transverse wall, a vertical projection or rib that reinforces the main supporting structure (primarily the outer wall of a building) and absorbs the horizontal pressure (the thrust from the arched ceiling, the pressure of the earth against the retaining walls, hydrostatic pressure against the foundation of a dam). The cross section usually increases toward the base of the wall (smoothly or with ledges). Against small horizontal thrusts, the cross sections can remain at one height. Buttresses can be made out of stone, concrete, or reinforced concrete. The stone buttress was one of the principal elements of Gothic structures. Buttresses are widely used to reinforce walls during the restoration of architectural monuments.

buttress

[′bə·trəs]

(architecture)

An upright projection that supports or resists lateral forces in a building.

(botany)

A ridge of wood developed in the angle between a lateral root and the butt of a tree.

(civil engineering)

A pier constructed at right angles to a restraining wall on the side opposite to the restrained material; increases the strength and thrust resistance of the wall.

(paleontology)

A ridge on the inner surface of a pelecypod valve which acts as a support for part of the hinge.

buttress

buttresses

An exterior mass of masonry set at an angle to or bonded into a wall which it strengthens or supports; buttresses often absorb lateral thrusts from roof vaults. Also see flying buttress, hanging buttress.

buttress

1. a construction, usually of brick or stone, built to support a wall

2. either of the two pointed rear parts of a horse's hoof