COMPONENTS OF THE ARCH STRUCTURE

The main structural components of the arches are

1. Abutments: These are the structures at the edges of the arch on which

the arch rests. They are also termed supports, which are used to resist lateral

loads due to arch action.

2. Crown: Crown is the point on the Arch with the highest elevation.

It is also termed voussoirs. The main function of the crown is that it takes up

the external load (in a downward direction) on it and coverts the load into

lateral force or thrust, which is transmitted to the supports and finally

to the ground.

3. Springing: The connecting junction between the Arch rib and the

An abutment is called a spring.

4. Span of arch: the clear horizontal distance between two supports of an

arch is called the span of the arch. Generally, the span of the arch in case

of tied arches carrying the highway will be in the range of 75m to 250m.

In the case of railways, the span range would be 50m to 200m.

5. Rise: The perpendicular distance between the line of action of the support

and the crown point of the arch. The height of rise in an arch as in the

case of a parabolic arch subjected to the entire udl is generally opted as 1/3

of span. If the arch is subjected to unsymmetrical loading, then the height

of rise in the parabolic arch is generally taken as 1/5 to 1/6 of the span.

(Ref: Lipson & Haque ,ASCE ,1980).

Er. SP.ASWINPALANIAPPAN., M.E.,(Strut/.,)

Structural Engineer

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