VDA - Arch Flashcards
A curved structure for spanning an opening, designed to support a vertical load primarily by axial compression
Arch
An arch constructed of individual stone or brick voussoirs
Masonry arch
An arch-shaped to develop only axial compression under a given loading. This shape may be found by inverting the funicular shape for a cable carrying a similar loading pattern. It is subject to bending if the loading pattern changes.
Funicular arch
A fixed frame structure having an arched form
Fixed arch
An arched structure of timber, steel, or reinforced concrete, constructed as a rigid body capable of carrying bending stresses
Rigid arch
A two-hinged frame structure having an arched form
Two-hinged arch
A three-hinged frame structure having an arched form
Three-hinged arch
Any of the wedge-shaped units in a masonry arch or vault, having side cuts converging at one of the arch centers
Voussoir
The first voussoir resting on the impost of an arch
Springer
The wedge-shaped, often embellished voussoir at the crown of an arch, serving to lock the other voussoirs in place
Keystone
The height of an arch from the spring line to the highest point of the intrados
Rise
The exterior curve, surface, or boundary of the visible face of an arch. Also called back.
Extrados
A decorative molding or band on the face of an arch following the curve of the intrados
Archivolt
The inner curve or surface of an arch forming the concave underside
Intrados
The point at which an arch, vault, or dome rises from its support
Spring
The highest part or point of a convex construction, such as an arch, vault, or roadway
Crown
Either side of an arch curving down from the crown to the impost
Haunch
The uppermost part of an abutment, often in the form of a block, capital, or molding, from which an arch springs
Impost
The triangular-shaped, sometimes ornamented area between the extrados of two adjoining arches, or between the left or right extrados of an arch and the rectangular framework surrounding it
Spandrel
An archway having sides or jambs not at right angles with the face of its abutments
Skew arch
Any of several concentric rings of masonry forming an arch, esp. when each project beyond the one below
Order
A temporary framework for supporting a masonry arch or vault during construction until the work can support itself
Centering
A board used as centering for a flat arch, slightly crowned to allow for settling of the arch. Also called camber slip
Camber piece
A crosspiece connecting the ribs in a centering. Also called bolster.
Lag
The manner in which an arch transforms the vertical forces of a supported load into inclined components and transmits them to abutments on either side of the archway
Arch action
The median line of an arched structure
Arch axis
The set of resultants of thrust and weight each part of an arch imposes on the next lower one. For bending to be eliminated throughout an arch, this must coincide with the arch axis.
Line of thrust
The outward force or pressure exerted by one part of a structure against another
Thrust
The thrust of an arched structure on its abutments, proportional to the total load and span, and inversely proportional to the rise
Drift
The part of a structure receiving and supporting the thrust of an arch, vault, or strut
Abutment
An iron or steel rod serving as a structural tie, esp. one keeping the lower ends of an arch or frame from spreading
Tie rod
A stone or course of masonry having a sloping face against which the end of a segmental arch rests
Skewback
An arch having a horizontal intrados with voussoirs radiating from a center below, often built with a slight camber to allow for settling. Also called jack arch.
Flat arch
An arch having continuously curved intrados, esp. a semicircular one
Round arch
A flat arch having voussoirs inclined to the same angle on each side of the center
French arch
An arch having a semicircular intrados
Roman arch
An arch struck from one or more centers below the springing line
Segmental arch
A primitive form of arch consisting of two stones laid diagonally to support each other over an opening
Triangular arch
A false arch is constructed by corbeling courses from each side of an opening until they meet at a midpoint where a capstone is laid to complete the work. The stepped reveals may be smoothed, but no arch action is effected.
Corbel arch
An arch having one impost higher than the other
Rampant arch
An arch resting on imposts treated as downward continuations of the archivolt
Stilted arch
A round arch resting on two large corbels with curved faces
Bell arch
An arch having an intrados that widens above the springing before narrowing to a rounded crown. Also called Moorish arch.
Horseshoe arch
An arch having a cusped intrados with three round or pointed foils
Trefoil arch
A three-centered arch having a crown with a radius much greater than that of the outer pair of curves. Also called anse de panier.
Basket-handle arch
An arch having a pointed crown
Pointed arch
A pointed arch having two centers and radii equal to the span
Equilateral arch
A pointed arch, esp. one having two centers and equal radii
Gothic arch
A four-centered arch having an inner pair of curves with a radius much greater than that of the outer pair
Tudor arch
A pointed arch having two centers and radii greater than the span
Lancet arch
A pointed arch having two centers and radii less than the span
Drop arch
A pointed arch having two centers and radii less than the span
Surbased arch
A pointed arch, each haunch of which is a double curve with the concave side uppermost
Ogee arch
