If you are not from civil background then you might wonder what is an arch, Let’s answer it. An arch is a curved shaped structure constructed with wedge shaped unit to support the weight of the wall above it. In an arch, blocks or bricks are arranged in such a manner that it can support each other and load bricks above it. The weight of the above wall is transferred through piers or abutments.
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Parts of Arch
Arch can support the load of wall above it through its various components. Let us look in detail about parts of arch:
1. Pier or abutment
The support on which an arch rest is called a Pier or abutment.
Both terms are used interchangeably but there is a slight difference. Abutment are the end support when multiple arch are there and piers are common support for two arches.
2. Soffit or Intrados
Soffit or Intrados is the inner surface of an arch.
3. Extrados
Exterior surface of an arch or the external surface is called extrados.
4. Arch Ring
An arch ring is a set of bricks or blocks having curves similar to that of an arch.
5. Arch Block or Voussoirs
Voussoirs or arch block are wedge-shaped structure that forms the arch.
6. Crown
The highest part of an arch or the topmost point of the extrados is called a crown.
7. Springer or Springing Stone
The first stone of an arch block or voussoir is called the springer or springing stone.
8. Springing Line
The line joining the two springing stones on both side of the arch is called the springing line.
9. Springing Point
Extremities of the intrados are called the springing points.
10. Keystone
The top most wedge shaped block of an arch is called a Keystone.
11. Striking Point or Center Of Arch
A geometric point is an arc forming arch rings, intrados of arch and extrados of arch.
12. Span of Arch
The span of the arch is the horizontal distance between the two support, that is between piers or abutments.
13. Skew-back
The surface on which the arch is supported is called a skew-back.
14. Rise of Arch
The Vertical distance between the springing line and the topmost point on intrados is called as the rise of an arch.
15. Depth of Arch
The perpendicular distance between the intrados and extrados is called the depth of arch.
16. Spandril
Triangular walling surrounded by the extrados of the arch, a horizontal line from the crown of the arch, and a perpendicular line from the rising of the outer curves are called the spandril.
17. Haunch
The part below the line joining the crown of the arch and skewback is called a haunch.