Glossary · C
Catenary
Also called catenary arch, catenaries
The curve of a chain or cable hanging freely under its own weight (y = a·cosh(x/a)); turned upside down, it is the ideal shape for an arch carrying its own weight.
See also: Thrust line
Rules that use the word
An arch is named by its curve. Classify arches by the geometry of the intrados: the number and position of the centres (one for round and segmental, two for pointed, three or four for basket and Tudor arches), or a single continuous curve (ellipse, parabola, catenary), and distinguish true arches, with voussoirs, from corbelled “arches” of oversailing courses.
The line of thrust must stay inside the arch. A masonry arch stands if a line of thrust (the path of the compressive force through it) can be drawn entirely within its thickness; the catenary arch contains its own line of thrust exactly, the semicircle only if it is thick enough.
Where it appears in the book
In the chapters The Arch, Frame and Skin.
Nearby in the glossary
Carpet bedding · Cartouche · Casement · Catena d’acqua · Cavea · Cavetto · Cavetto cornice · Cejiao