Graphical Construction Glossary >> masonry. >> arch >> Segmental Arch

Segmental Arch

An arch that has a curve formed from a segment of a circle. Sometimes called a circular arch.

This arch is so named because it formed from a segment of a circle. It is an extremely common form of arch both in stone and in brick. It is easy to see from the sketch that all the vousoirs are made to the same pattern.

An old brick arch seen in Haarlem, Holland.

The old stone bridge crossing the Arno in Florence. The Ponte Vechio.

The flatter segmental shape has long been used for bridges. With the segmental arch the flatter it gets the more of it's thust is delivered sideways to the abutments or embankments at each end of the bridge. With a bridge it is easy to build these abutments in a very massive and solid manner to resist the sideways thrust.

Not so in ordinary buildings. In the building in Florence (or anywhere else for that matter) that were built at the same time as the Ponte Veccio segmental arches are only seen as small spans over doors and windows. Larger spans in those days had to use colonnades of Roman or semicircular arches that deliver most of their thrust vertically down to the supporting columns.

Of note in the photo above are the recesses in the masony just below the springing line of the arches. The builders would have built the bridge masonry abutments or supports first. Then they would have laid across timber beams to support the arch centring , resting on top of the solid masonry. In the fashion of the builders in medieval times they left the holes in the masonry after the arch centring was stripped or removed. Another example of this are the large amounts of putlog scaffold holes seen in old buildings.

• Segmental Arch:-Back to top
  
•  
• << BACK: bullseye arch
• :Islamic arches NEXT >>

If you didn't find exactly what you are looking for try this search tool that will search the site and the web.

"What can be added to the happiness of a man who is in health, out of debt, and has a clear conscience?
Adam Smith 1723-1790

"When we build, let us think that we build for ever."John Ruskin 1819-1900