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All  Sorts  of  Arches

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In this page we look at a wide range of masonry arches

which demonstrate the great diversity of shapes available to a builder. 

We include some examples that are not arches at all, even when they

are disguised as such.  We start with the flattest examples.

Round  Arches

ArchFlatJune.jpg (86933 bytes)This has rounded ends, but is it an arch at all? In principle there could be a funicular inside the bricks, but in practice is possible that there is a steel beam inside.

ArchMesneA.jpg (71421 bytes)This lintel has a keystone, but the voussoirs form two parallel sets. If you look at window lintels, you will see a vast range of different styles. A flat arch like this is called a jack arch.

FalseArch2665.JPG (170272 bytes)FalseArchXS2665.JPG (50799 bytes)The example shown here is a set of sharply angled windows. The angle is such that there is nowhere for the thrust of the jack arches to go, and in fact one has sagged, damaging the brickwork above. The second picture has been compressed sideways to clarify the sag. It is actually quite possible that these are not arches at all, and that the "voussoirs" have simply been stuck on a beam.

OddArchB.jpg (75643 bytes)Is the inner construction a very flat arch?

ArchFlatJA.jpg (120058 bytes)Another flat arch

ArchJz.jpg (135660 bytes)Not quite as flat.  The treatment of the abutments is not perhaps as good as it could have been.

BuildingJK.jpg (147901 bytes)These very interesting buildings include a number of openings which look like elliptical arches.

ArchKSJune.jpg (59299 bytes)The large abutments are an amusing touch, though rather bulbous, but the keystone is intrusive.

VeryFlatArch.jpg (156782 bytes)This flat arch includes rather sudden changes of curvature, not only near the ends, but around the crown, making the arch a semi-pointed one.

WideEllipseF.jpg (129358 bytes)In this example, the curvature changes more smoothly. Do you think this is better than the previous example?

ArchTrapezoid.jpg (76656 bytes)This is not a pointed arch, but it is so angular that it can hardly be counted as round either. The point is that the shape of the voussoirs is not very important: what matters is the position and alignment of the interfaces between them, and the distribution of weight in the structure.

TunnelJ2.jpg (95112 bytes)Most tunnels are arches or complete circular tubes.

ArchRoofJuneA.jpg (113688 bytes)ArchRoofB.jpg (71896 bytes)Architects sometimes place unusual structures on top of their buildings. This example appears to be a bridge, comprising a trussed arch.

SemiSquinch.jpg (66809 bytes)These arches in Gloucester cathedral are parts of conical surfaces. In the extreme case, the cone goes to a point, and the arch is usually in the corner of two walls; such an arch is called a squinch arch.

KeystoneMulti.jpg (92981 bytes)These windows not only have keystones - they have protruding blocks all round - making for a rather unsettled appearance.

flatarchesbath5313.jpg (128054 bytes)Here is a series of very flat arches, which are of course short segments of circles. Hence they are called segmental arches. Note the supporting pillars, which are not straight edged cylinders, which would be the "functional" shape. They are slightly bulged, giving the impression of taking the weight. Functional design does not have to be plain or ugly, because one function of a building can be to please people. This may not lead to designs that please everyone, because the people being pleased may be a small subset of the population. The  British brutalist architecture of the 1960s may have pleased the experts of the time, but it may well not have pleased all the people who had to live and work in it.

Pointed  Arches

ArchFlatJuneA.jpg (59315 bytes)This is a about as flat an arch as you could imagine. It is possible that a steel beam is present somewhere.

ArchTudor643.jpg (94370 bytes)This Tudor arch is almost as flat. It must exert considerable thrust at the sides.

Seville8.jpg (96590 bytes)Some of these arches in Seville include ornamentation which hints at slightly pointed arches.

EastWindow.jpg (43587 bytes)A very large window at the east end of Gloucester cathedral. Like many other such windows it includes mullions which provide some intermediate support, and it may be said that such openings are not true arches. They would, however, probably survive without the mullions, which are really there to provide rigidity for the huge area of glass.

GlosFanB.jpg (65664 bytes)OgeeArchSpA.jpg (69795 bytes)The ultimate in pointed arches - the ogee arch. The shape may be purely decorative, or it may be based on a misconception about the way forces are distributed in a structure. In a compression structure such as an arch, the forces in the curve must be counteracted by forces from the outside of the curve to the inside. For an arch these forces are supplied by the weight and by any live load. For the ogee arch there are no forces to balance the reverse curvature. It only stands up because of the thickness of the voussoirs. The next diagram shows a few examples of the way that forces can work with curves.

Please see also these pages about architecture.

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Arches One

Arches Two

Arches Three

Arches Four

Arches Five

Arches Seven

 

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