Arches are an economical and aesthetic means of spanning openings. An arch is defined as an arrangement of small units of blocks placed side by side over openings in the form of some curve.
The blocks support themselves by mutual pressure and the whole arch is maintained in equilibrium by the resistance offered by the supports.
Arches can be a cost effective alternative to the lintels. In addition they look lot more appealing than flat and dull lintels. Arches can be of different shapes and sizes depending upon span and availability of skilled masons. Most common arch shapes come in semi-circular, pointed, corbelled & bell shapes.
When to use an arch and which type should be adopted?
Arches can be used over all types of openings and also in verandas as colonnades. It is an economical alternative of RCC lintels or beams.
Parabolic arches are one hundred percent compressive. The others are subjected to bending and compression. However, simplicity of construction should be the deciding factor and hence flat, segmental or semi circular arches are recommended.
Advantages
• They are economical due to the use of local materials like bricks.
• They look aesthetically more pleasing.
Limitations
• Need form work
The traditional RCC lintels which are costly can be replaced by brick arches for small spans and save construction cost up to 30–40% over the traditional method of construction.
Corbel Arch:-
THE inexpensive way of spanning a hole in a wall is the simple “corbel’ arch. Each row of bricks projects 2.25-inches beyond the course below until the bricks meet together in the middle. No fore work or shuttering is necessary. This picture also demonstrates the fact that if you remove a door or a window, the whole wall will not fall down. Probably nothing will fail at all, but if it does, the maximum will be the amount of wall within the triangle above the frame. This triangle of bricks is, in fact, all that a lintel carries, and not the whole wall and half the roof above it.
Corbel arch can span opening up to 5 meters.
Do not allow the architect, the engineer, and the building contractor to be dictators. You tell them what you want!
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