Lintels

LINTELS

Lintel: Lintel is a short beam with its ends built into a wall. It is a horizontal structural member placed over small openings of the wall for door, window, ventilator, cupboard, etc.

Note: Width of the lintel is equal to the width of the wall.

Bearing of the lintel provided on the supporting wall is equal to the height of the lintel.

Functions: Lintel carries the weight or load of the masonry wall constructed above it. transmits the same to the supporting walls on its either side.

1. CLASSIFICATION OF LINTELS

1. Timber Lintel: It is made of hard wood like Teak. It is embedded into the masonry wall at its ends. These lintels are poor in strength, non-fire resistant and liable to be attacked by white ants. Cost of timber is also high. Therefore, these lintels are not used.

2. Stone Lintel: It consists of chisel-dressed stone slabs either a single piece or more than a piece. It is not suitable for large spans, since it is very heavy. It is used in stone masonry structures such as temple, etc.

3. Brick Lintels (Fig. 1) ,

Brick Lintels consist of bricks placed on end or on edge. Brick lintels are weak in strength. Hence, they can be used for light loads and for small openings or spans of up to 1 meter only.

4. Steel Lintels (Fig. 2)

Steel Lintels use Rolled Steel Joists or Channel Şections. Steel lintels are used for large openings and heavy loads.

Rolled steel joists are embedded in concrete to (i) increase its width to match with the width of the wall and (ii) protect from rust and corrosion.

5. Reinforced Cement Concrete Lintels (R.C.C. Lintels)

Advantages: R.C.C. Lintels are highly durable, strong, rigid, easy to form and fire-proof. These are economical and simple in construction.

Uses: R.C.C. Lintels are used for any span length of openings and for carrying any load. These are commonly used now-a-days, replacing practically all other materials for lintel.

(i) R.C.C. Lintel over Interior Door Opening

Fig. 3 shows a lintel provided over the door opening in an Interior Wall. The lintel is designed as a small rectangular beam, resting on masonry wall at its ends.

R.C.C. Lintels may be Pre-cast or Cast-in-situ. Pre-cast R.C.C. Lintels are used for small spans up to 2 m only. But, R.C.C. lintels are generally cast-in-situ. For Cast-in-situ lintel, a centering is erected, reinforcement of rectangular or square cross-section is placed and concreting 1:2 : 4 is done, compacted and cured.

(ii) R.C.C. Lintel over Exterior Window Opening

Fig. 4 shows a lintel provided over a window opening in an Exterior Wall. R.C.C. lintels for outer doors and windows have overhanging projections. These projections are called Sunshades. Sunshades protect the doors and windows from sun and rain.

2. EFFECTIVE LOAD ON LINTEL

Fig. 5 shows Effective Load coming on a lintel.

When Lintel is placed in the Middle of Wall Assume that when a lintel is placed in the middle of a wall, then the load on the lintel is distributed uniformly over its effective span for a height equal to half the effective span.

The lintel is designed to take the load of the wall in a triangular portion. The base of the triangle is equal to the Effective Span of the lintel. The included angle of the triangle is 60°.

When Lintel is placed near the End of the Wall

When the lintel is placed near the end of a wall, it is designed to support the load of the wall in the square area as shown. In this, the side of the square is equal to the effective span of the lintel.