Arch

Paris Triumphal arch ** //Arch// is a curved structure which supports the weight of a material over an open space.

Types of Arches
-Arch with one centre:

- Semi-circular arch: it is a semi-circular arch when the semi-circumference is in the highest point of the imposts. - Segmental arch: is is a segmental arch when the high of the rise is smaller than the bay. - Horseshoe arch: it is a horseshoe arch if the curve of the arch overpasses the semicircle.

-Arch with two centers: - Lancet arch: it is a lancet arch when the two curves form an angle in the keystone.



Characteristics
The size of arches is limited only by the economy. The form may vary depending to the specific problems. The most efficient forms in masonry are semicircular segmental and pointed.

Arch in Urban Planning
Arches have been used in the:

-Construction of bridges and aqueducts. -Landscaping because it defines public and private spaces such as: -Squares -Front of at building. - Inflows of a city.

Advantages
-An architect designs arches near each other to create great stability.

-It gives a better aspect, it’s more elegant. - Arches made with iron or steel are very stable. - Arches made with iron or steel can also be flexible


 * Disadvantage **

-It is very weak when it comes to support.