Intersecting ribs

See also: Cross, Warhead

The intersecting ribs is, with the Arc-boutant, an essential characteristic of the Gothic architecture.

the Romanesque architecture, which precedes the Gothic, is characterized by arcs in semicircular arch and vaults. These Romance vaults are massive and very doors, they require thick bearing walls, generally reinforced by buttresses coupled of place in place.

With the ogival architecture, the Gothic brings an elegant solution to the problems of forces which the novel knows. The central idea of intersecting ribs, is to make vaults which rest not directly on walls, but on these cross warheads, and the warheads itself converge towards pillars. The push is not any more distributed throughout the wall, but is concentrated on a point at the top of the pillar. Blow, the wall itself is not used for nothing and can be emptied (to place Vitraux, for example) and the push received at the top of the Pilier S can be easily compensated by propping up.

The intersecting ribs indicates the diagonal veins formed by the intersection of Voûte S in cradle. It can be quadripartite or sexpartite (according to whether it crosses 2 or 3 warheads, drawing 4 or 6 voûtains). The ribbed vault is known as barlongue when it forms, with each Travée, a rectangle whose longest side is perpendicular to the Nef. It is known as oblong in the contrary case.

Its veins name warhead S, Lierne S and Tierceron S.

A system by intersecting ribs and propping up is much more delicate to balance than a simple vault in lime pit curves (it is not an spelling error: lime pit = without accident), this technique reflects a better control of the balance of the forces. This same control also results in the thinning of the vaults: being calculated better, of a range proportionally weaker, and being partitioned, they can be thinner without being likely to flame. It is what gives the impression that “there is nothing heavy”: indeed, the vault is intrinsically lighter, and its construction gives an additional impression of lightness. The skilful architect adds processes to give an impression visually “to float in the air”.

Lastly, the roof with the top of the vaults is necessary to avoid rainwater infiltrations, which, if not, would end up ruining the building. Indeed, before the invention of intersecting ribs, the only manner of making great ranges was to assemble vertical walls, and to pose a roof above, without intermediate vault (as in the basilicas paléochrétiennes). The problem of this fitting is that it is too much sensitive to the fires (the proof a posteriori: none survived).

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