Rib

Rules that use the word

A ring of windows at the foot of the dome. Pierce the base of the dome with a close ring of windows between buttressing ribs, so that the shell seems to float on light rather than to rest on the arches.

Concentrate the loads; fill the rest with glass. Gather the weight and thrust of the vaults onto a few points by ribs, carry them down piers and out across the aisles by flying buttresses to external buttress piers, and the wall between the supports carries almost nothing, so it can be opened into windows.

The width of the choir is the measure of all. Proportion every member of a vaulted choir from its clear width: the wall a fixed fraction of the width (a tenth, as the rule is usually read), and buttresses, window jambs, mullions and ribs as simple multiples or fractions of the wall.

Two shells tied by ribs. Build a great dome as two shells (a thick inner one that carries, a thin outer one that protects and gives the silhouette) joined by ribs and locked at the top by a ring under the lantern.

Transverse arches beneath a barrel. Strengthen a barrel-vaulted nave with transverse arches at every bay, springing from shafts on the piers; they stiffen the vault, mark the bays and serve as ribs on which the vault can be built bay by bay.

The problem of the oblong bay. Two semicircular barrels of different spans rise to different heights. To groin-vault an oblong bay the narrower barrel must be stilted or flattened, and the groins then wander out of plane: the difficulty that pushed builders towards ribs and pointed arches.

Where it appears in the book

In the chapters The Arch, Vaults, Domes, Frame and Skin, The Ancient World, Byzantium and the Early Church, Romanesque and Gothic, South and Southeast Asia.

A feature of Romanesque, Gothic architecture.

Nearby in the glossary

Reinforced concrete · Relieving triangle · Respond · Ressaut · Rib vault · Ribbon window · Ridge · Ridge rib