1. Ninoska Ruiz. Sarahy Carrillo.
ARCH.
Ninoska Ruiz.
Sarahy Carrillo.

2. Content: Definition. History. Elements and parts of arch.
Types of arches according to the form of the intrados.
Construction.
Conclusion.
References.

3. Definition:
An arch is a curved structure located between two intermediate supports; it can resist more compression force than the lintel and allows the use of bigger spans.

4. History.
Arches appeared as early as the 2nd millennium BC in Mesopotamian.
The Egyptians used it in tombs and vaults but never for monumental architecture, such as temples.
The Greeks also used the arch solely for practical constructions, but many of the principles they developed were later exploited by the Romans who were the first to apply the technique to a wide range of structures.
In Roman times the arch were fully exploited in bridges, aqueducts, and large-scale architecture.
The Romans also used arches for common purposes, such as in the building of bridges and aqueducts.
Arches continued to be used in Medieval times, especially in cathedrals, where they helped support the great weight of the stone ceilings, especially when walls were weakened by the presence of many windows.
Ur City. Mesopotamian.
In ancient Egypt,  Ramesseum 
stores were built with arches of adobe.

5. Steel, concrete, and laminated-wood arches of the 20th century have changed the concept and the mechanics of arches.
The Gateway Arch.
architect Eero Saarinen  1965.

6. The arch is an incredible architectural discovery It comes in many shapes: semicircular (Roman), segmental (less than half a circle), or pointed (Gothic).

7. Parts of Arch Keystone Voussoir Back Impost Intrados Rise
Clear span, "Bay"
Abutment

8. Types of Arch
Arches are classified according to the shape of the intrados in:
Circular arches from a single center.
Circular arches of more than one center.
Non-circular arches of two centers.

9. Construction:
An arch requires all of its elements to hold it together.
One answer is to build a frame (historically, of wood) which exactly follows the form of the underside of the arch.
The voussoirs are laid on it until the arch is complete and self-supporting.

10. Conclusion:
Wide openings could be spanned with small, light blocks in brick as well as stone, which were easy to transport and to handle.
Arches have been widely used throughout history. They are very strong and useful structures. Thanks to them it has been possible to create domes and vaults.
The disadvantage however is that arches require reinforcements to arrest the horizontal forces given from the loads above.

11. References http://en.wikipedia.org/wiki/Arch
Encyclopaedia Britannica, Vol. 1. Chicago: Encyclopaedia Britannica, Inc., 1974, pp