Additional features of superstructure

ADDITIONAL FEATURES OF SUPERSTRUCTURE

 

1. ARCHES

The Romans perfected the technique of construction of masonry arches and many of their bridges and aqueducts were carried over arches. Some of them exist even today and hence it is an age old construction method. An arch is a curved member that is used to span an opening and to support loads from above. Arches are used in modern buildings to bridge over the openings for doors and windows.

Classification of Arches

Arches are classified according to their geometry or shape. Their shape is selected according to the architecture of the building. They can be made of bricks, stones, blocks, etc. They can span wider openings and carry a much greater load than horizontal beams or lintels (detailed in Chapter 6) can support. The main types of arches (Fig. 1) are given below:

Corbel arch: It is constructed by corbelling without centring.

Segmental arch: It is in the form of the segment of a circle.

Semi-circular: It is in the form of a semi-circular shape. Other types of arches can be elliptical, parabolic and so on.

Pointed arch or Gothic arch: It is built around triangles and formed of segments meeting at the apex.

 2. DOORS, WINDOWS AND VENTILATORS

The cost of providing doors, windows, and ventilators in a building can work out to about 18 to 25 percent of the total cost of civil works. This is due to the fact that expensive material such as wood, fittings and skilled labour are involved in making them.

Doors are provided as external doors at various entries and exits of the building. Internal doors are provided between rooms in a building. External doors should be more robust than internal doors for safety. Windows are provided on outer walls for natural light and ventilation. Ventilators are used for air circulation in bathrooms, stores, etc., instead of windows.

 

3. STAIRS AND LIFTS

Stairs, electric lifts, ramps and escalators are the commonly used means of vertical transportation in buildings. For buildings up to three floors, only stairs are usually provided. For buildings with more than three floors, both electric lift and stair are to be provided. Spiral and helical stairs are very ornamental in nature.

 

4. TEMPORARY WORKS FOR CONSTRUCTION

Temporary structures provide support or means of access to permanent works during construction. The permanent works include concreting, plastering and erection of prefabricated members. The temporary works which are mainly used are briefed below:

Scaffolding: It provides a temporary safe working platform for erection, maintenance, construction, repair, access and inspection. The most common piece of structure used in scaffolding is the scaffold tube. The tube generally comes in two thicknesses, 3.2 mm and 4 mm.

Falsework: It involves a temporary structure used to support other permanent structures until they can support themselves.

Formwork: It is the term used for a temporary mould into which concrete is poured and formed. Traditional formwork is fabricated using timber. It can also be constructed from steel.

 

5. PAINTING

Paint is used to decorate, protect and prolong the life of natural and synthetic materials. It acts as a barrier against environmental conditions. The major materials used for painting of buildings are:

(i) Cement paint: It is made from cement and additives. It is for exterior use.

(ii) Dry distemper: It is water based paint. Major constituents are chalk, lime, water and coloring agents. It is used for interior walls and ceilings. It is the most economical type of painting.;

(iii) Emulsion /Plastic paint: It is water based paint. It is a liquid having fine suspended particles. ...It provides a rich and matt finish to interior walls. It is washable and stains can be removed.

(iv) Enamel paint: It is water based or oil based paint. Oil based paint air dries to a hard and glossy finish.

(v) Primers: A primer or undercoat is a preparatory coating put on materials before painting. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted.

 

6. BUILDING ACOUSTICS

Building acoustics is the complex science of controlling noise in buildings. This includes the minimisation of noise transmission from one space to another. It also includes the control of the characteristics of sound within spaces themselves. They can have a significant impact on health, communication and productivity. They can be particularly significant in spaces such as concert halls, recording studios, lecture theatres and so on, where the quality of sound and its clearness are very important.