The arch buildings created by the Romans are considered to be one of the most efficient means of supporting weight and spanning wide spaces because of its strong form. It is able to withstand winds because most of the winds force goes through the arches. This style of architecture saved on building materials because of all the open space. Solid walls require a lot more materials.
The weight and thrust of an arch is forced sideways and downward onto the supporting piers that hold up the curved portion of the arch. The arch itself is built of wedge shaped blocks that are called voussoirs. The voussoirs are placed above the other over semicircular scaffolding. Once the keystone is in its place the arch becomes stable. Even though the arch was used by the Greeks, the Romans used this style of architecture a lot.
Pointed barrel vault showing direction of lateral ...
Barrel Vault at the The Cloisters in New York City...
Vault from above.There are two different types of vaults that are created when building with arches. The first one is a barrel vault. A barrel vault is created when an arch is extended in either direction. Barrel vaults can be any length, be straight or curved, making passages alongside an oval or rounded area. A barrel vault requires extra support by reinforcement on the exterior. A groin vault is formed by two barrel vaults of the same dimensions intersecting at right angles. The junctures at which the two vaults meet are elliptical ridges, called groins. In the simplest form of groined vault, the two conjoined vaults are of the same size and the floor of the vault is square; if the vaults are of different sizes, however, the floor of the vault is rectangular and the two areas of the ceiling between the groins are of unequal shape and size. The Coliseum is a great example...