ARCH

DEFINITION:
The arch is a type of structure that spans a place between two columns and suports a weight in the form of a semi circular structure.

The arch has the ability to eliminate tensile stresses in spanning an open space. All the forces are resolved into compreddive stresses. This is useful because several of the available building materials such as stone, cast iron and concrete can strongly resist compression but are very weak when tension, shear or torional stress is applied to them. By using the arch configuration, significant spans can be achieved. This is because all the compressive forces hold it together in a state of equilibrium.

There are different types of arch such as:
 * Blind arch: it is covered with solid construction so it does not serve as a door or a window.
 * Dome: it is a type of arch rotated in a 360 degree angle over its base.

