This Innovative and economical Construction System of Geodesic Domes minimizes the geometrical complexities of construction and engineering difficulties.
N G Bhagavan, Retired Scientist, Center for Innovative Building Technologies (CIBTech), CSIR-SERC, Chennai.
A geodesic dome is a semi-spherical shell structure assembled with a network of circles (geodesics) on the surface of a sphere. The geodesics intersect to form triangular elements that are rigid and distribute the stress all across the structure. Though they are domes due to their shape, they don’t contain curved surfaces! They are constructed by a series of one dimensional (one-D) structural members sequentially arranged as series of plane triangles, to take the shape of a dome.
In the 1950s the geodesic domes became popular in the United States due to the efforts of Buckminster Fuller, an American engineer who guided the transfer of this technology and commercialized their construction in many parts of the country. Geodesic Domes have been built for various building infrastructural applications such as, theatres, town-halls, auditoriums, gymnasiums, camp-sites, exhibition-halls, and even for private housing.
Geodesic dome buildings have got both the structural advantages and the economic advantages. Unlike a conventional building, where one needs to build walls separately and a roof over it, geodesic dome contains integrated walling and roofing.
The domes can be designed and built with various materials such as steel, wood, aluminium, plastic, bamboo, coco-lumber, country wood and other locally available construction materials.
However, geodesic domes are not quite popular construction choices, due to the geometrical complexity of their shape and also due to the construction technology related issues - particularly their joints, hubs, and apexes, where four to six or more structural members are to be connected in various angles. This has given rise to a number of patented technologies.
In this context, to minimize the geometrical complexities of construction and engineering difficulties, an innovative construction system of geodesic domes, named as Bhavan Domes Technology, is being developed and promoted by a retired CSIR-scientist. The name ‘Bhavan Domes’ reflects the fact that this innovation has originated in India.
Bhavan Domes Technology Concept
Bhavan domes are geodesic domes by their geometrical shape, but the difference is in their respective construction systems. Geodesic domes are built with the one-D structural members and joined with highly complex joints (hubs), whereas the Bhavan domes are constructed with the two- D triangular panels.
- Unlike geodesic domes, the Bhavan domes don’t need to have any complex structural joints for construction! However, the Bhavan domes do need a simple series of pivotal joints for connecting triangular panels in the defined geometric-sequential way.
- Since the Bhavan domes are built with two-D triangular panels, they are structurally more stable, and they form relatively more efficient and stronger structures.
- It is not only the construction methodology that is different, but also the structural design methodology is also different in Bhavan domes, when compared to that of Geodesic domes.
- Both types of domes can be built with different construction materials.
Economy of Bhavan Domes
- To cover the plinth area of 300- sq.ft., conventional house requires total (surfaces including walls plus roof) construction of 1000-sq.ft., compared to that of 647-sq.ft. for dome.
- For building same plinth area of 300-sq.ft., it requires a 20’3”- diameter size of Bhavan dome.
- This construction requires 647-sq.ft. of surface area of integrated walling and roofing.
- When compared to conventional buildings, Bhavan domes require less than 65% of construction area only, for covering any given plinth area! It means, there is more than 35% of economy achieved due to shape of Bhavan domes.
- Dome shape is obtained by cutting-down the unwanted top corners of conventional cubical types of buildings. Generally these top corner spaces are unused, and don’t find any domestic utility.
- Bhavan dome weighs only a fraction of whole dead-weight of conventional buildings, and hence it requires simple foundations.
- The economy of Bhavan domes is derived from not only its shape, but also due to simplified foundations and utilisation of locally available materials of construction. Thus, the economy is very much assured to minimum extent of one third of conventional construction costs.
- It is quite economical, as it consumes minimum construction materials.
- Bhavan domes construction enables to build minimum additional stocks of 25% extra building units (within the given budgets), due to the relative economy. The foundation is also simple and economical.
- Faster construction is one of the advantages of this technology. It would be possible to build this type of dome buildings within a week.
- To extensively promote Bhavan domes, systematic training is recommended since it is an innovative product.
- As a 3-dimensional structure, Bhavan domes offer effectively earthquake-resistant buildings.
- Being aerodynamic shaped, it also offers cyclone resistant buildings.
- Ferrocement Bhavan domes offer highly durable, fire-proof and water-proof buildings.
- Bhavan domes are ideal choice of buildings for reconstruction after earthquakes, cyclones, and other natural calamities.
- This disaster-resistant technology will improve the quality of life for millions of rural populations in the future.
- Extensive utilisation of Bhavan domes improves the national economic conditions and increases employment opportunities.
- Bhavan domes don’t require bricks and hence, saves fertile soil.
- This technology also saves stones and other conventional building materials, to ensure environmental conservation.
Bhavan domes technology is an innovative building system of viable construction technology with both economic advantages and structural advantages, that is to be utilised for extensive construction of future rural housing and various other types of public buildings in the country.
For mass constructions, Bhavan domes building technology of precast triangular ferrocement panels, sequentially assembled as in-situ construction, is a very effective engineering solution to meet future rural housing demands.
Ferrocement Bhavan domes offer fire-proof, water-proof, cyclone-resistant and earthquake-resistant buildings. This technology can be designed and adopted to utilise various other locally available materials across the nation. It needs well planned awareness seminars and effective training programmes to extensively promote the Bhavan dome technology. India can become the technical leader to effectively transfer this technology across other developing countries.
It is a very sound concept for construction of durable low-cost structures for serving various purposes. Active agencies in field of rural development, health programmes, small storage structure etc. can use this technology and achieve good saving in construction cost and time.