18 Different Component Parts of an Arch

18 Different Component Parts of an Arch

Arch is the structure that is constructed over the opening of the windows, doors or cupboards, etc. The arch structure is also used in bridge construction. In Ancient times, it was the most common structure used in any type of building. Arch may be circular, elliptical or any other shape. It consists of wedge-shaped blocks of stone, bricks, etc. It may be made of steel or R.C.C in case of bridge construction. In this article, I am going to share different component parts of an arch and also some technical terms used in arch construction.

18 Different Component Parts of an ...
18 Different Component Parts of an Arch - CivilNotePpt
18 Different Component Parts of an Arch
18 Different Component Parts of an Arch

1. Abutment

The abutment is the end support of an arch. In other words, it is the end support of a span on which the arch rests. The abutment may be walls or columns in the case of buildings and retaining walls in the case of a bridge. An abutment should be designed in such a way that it can easily withstand arch thrust.

Different Component Parts of an Arch - #1. Abutment

2. Piers

Piers is also a supporting member of an arch, but it is the intermediate supporting member. Piers are used when a series of arch is constructed.

3. Arch ring

It is a course of wedge-shaped blocks, arranged in a curved form and supported on the abutments or piers.

Different Component Parts of an Arch - #3. Arch Ring

4. Intrados

This is the inner curved surface of the arch.

Different Component Parts of an Arch - #4. Intrados

5. Extrados

This is the outer curved surface of the arch, it is also known as the back of the arch ring.

Different Component Parts of an Arch - #5. Extrados

6. Soffit

The soffit is the bottom surface of the arch. Indrados and soffit terms are used to indicate the same thing.

Different Component Parts of an Arch - #6. Soffit

7. Span of the Arch

The span of the arch is nothing but a clear horizontal distance between the supports.

Different Component Parts of an Arch - #7. Span of the arch

8. Crown

The Crown is the highest part of an arch. In other words, it is the height points of the extrados arch.

Different Component Parts of an Arch - #7. Crown

9. Voussoirs

Voussoirs are wedge-shaped units by which the arch ring is created. These block units may be of brick, stone, or plain cement concrete. Voussoirs are also called arch blocks.

Different Component Parts of an Arch - #9. Voussoirs

10. KeyStone

Key stone is also a wedge-shaped block unit but it is larger than the voussoirs. This unit is placed at the highest point of the arch.

Different Component Parts of an Arch - #10. KeyStone

11. Skew Back

It is the splayed surface prepared on the top of an abutment or pier, to receive the arch. Arch work actually starts from skewback.

Different Component Parts of an Arch - #11.  Skew Back

12. Springing Points

These are the points from where the curve of an arch starts. In other words, these are the points at which intrados and skew backs intersect.

Different Component Parts of an Arch - #12. Springing Points

13. Springing Line

The springing line is nothing but the imaginary horizontal line joining the two springing points.

Different Component Parts of an Arch - #13. Springing Line

14. Springers

It is the first voussoir (or, beginning voussoir) at the springing level on either side of the arch.

Different Component Parts of an Arch - #14. Springers

15. Depth of the arch

It is the verticle distance between the intrados and extrados of an arch.

Different Component Parts of an Arch - #15. Depth of the arch

16. Haunch

If you imagine a line between crown and skewback, then the portion below the imagined line is known as Haunch.

17. Center of the arch

Center of the arch - Component Parts of an Arch

As its name suggests, it is the geometrical center of the curve of an arch.

18. Rise of the arch

Rise of the arch - Component Parts of an Arch

It is the perpendicular distance between the springing line and the highest point of the below curve(intrados) of the arch.

Read More:

Different Types of Lintel

Different Parts of a Building Structure

5 Component Parts of a Bridge