Classification Based on Number of Centres

On the basis of number of centres, the arches might be categorized as:

One-centred Arches

These arches have one centre only. Segmental arches, semi-circular arch, flat arches, horse-shoe arch and stilted arches come under this category. Sometimes, a perfectly circular arch, known as bull's eye arch as shown in Figure 10(a), is provided for circular windows.

                                            Figure : Arches Based on Number of Centres

Two-centred Arches

These arches are of several types but the popular ones are pointed arches and florentine arch as shown in Figures 9(e) and (g).

Three-centred Arches

Elliptical arches come under this category. Figure (b) shows a three-centred arch.

Four-centred Arch

It has four centres. Venetian arch is a classic example of this type. Other examples are the Tudor arch as in Figure (c).

Five-centred Arch

This type of arch, having five centres, gives a good semi-elliptical shape as is shown by Figure (d).