You can eliminate beams and columns in construction by using the load-bearing wall technique. HEMA VIJAY talks to Prof A. R. Santhakumar to find out more
In 1997, with his design for the Bicentennial Building of the College of Engineering at Anna University, structural engineering wizard Prof. A.R. Santhakumar introduced the city to the load-bearing wall system. This technique eliminates the need for columns and beams through the use of a reinforced masonry concept that involves structural concrete blocks. Santhakumar went on to design many such structures, including the Koyambedu bus shelter’s shell structure, one of the largest built spaces in the country without columns. A former dean and chairman of the Faculty of Civil Engineering, Anna University, a former emirate professor of IIT Madras and a former Adviser to Shelter Reconstruction and Rehabilitation, United Nations Team for Recovery Support, UNDP-India, Santhakumar was awarded a Lifetime Achievement Award at Construction Industry Awards 2013. He now provides consultancy services to several organisations in concrete construction engineering.
How is it possible to do away with supporting columns and beams? Please explain the load-bearing wall concept.
With framed buildings, frames are built with RCC and the walls are made with brickwork, and the walls don’t contribute to load resistance. Using reinforced masonry with structural concrete blocks (which have two hollows within a single block) is an alternative method of construction by which walls acquire load-bearing strength. In this type of construction, walls are built by aligning structural concrete blocks in a way that one block is placed over two half-portions of the two blocks beneath it, such that the hollows are still continuous and form a spatial channel, through which reinforcement is introduced by steel rods and concrete grout.
What kind of buildings can use this concept?
Load-bearing walls have the strength to support floors and roofs, resist wind, seismic effects, noise, heat or cold and fire. The building so constructed can be rectangular, square or circular, but symmetry should be maintained. The bicentennial building (in the university) happens to be a three-storey structure, but actually even a ten-storey building is easily possible with this technique, with proper design of the reinforcement in the blocks.
How did you start using this system?
Structural masonry hollow blocks are used all over the world for building walls. I came across reinforced structural hollow blocks when I was doing my Ph.D in earthquake-resistant engineering at the University of Canterbury, New Zealand. This technology is quite common there and load bearing walls are used precisely because they offer resistance to earthquakes, because in a reinforced wall system, the reinforcement runs in all directions, while in column supported buildings, the reinforcement happens only along the columns.
Is it possible to produce these structural hollow blocks in India?
These hollow blocks are produced by hydro-floatation technique, and are made by a few companies in India like Besser and Aeons. Companies that produce architectural blocks can easily acquire the technology to produce these blocks. Hollow blocks are made with concrete, with a strength clause as per Bureau of Indian Standard specifications.
Is the system cost effective?
It is cost effective, especially when the quantity of usage of these blocks increases. In fact, in the case of the bicentennial building, by going in for load bearing walls we were able to reduce the cost by about 25 per cent.
What can be done to revive this technique?
Load-bearing wall construction needs skilled workers and precise execution. But ordinary unskilled masons can be taught this technology and construction method with a day’s training. Workshops to sensitize builders and architects are also needed. In the long-term sense and to develop a pool of skilled workers in various areas such as concreting, fabrication of shell, finishing, and so on, we need to establish Industrial Training Institutes and Polytechnics, rather than relying on contractors and masons learning skills from their seniors.
Prof A. R. Santhakumar can be contacted at 9840142384.
The hollow blocks used are made with concrete, to BIS-approved strength standards
Without columns, spaces can be made more adaptable. You can also get flexible spaces by using temporary partitions.
The absence of beams reduces the floor-to-floor height by at least 30 cm.
Buildings supported by columns require deeper foundation work, because the load-bearing is concentrated at the columns. Eliminating columns reduces elaborate foundation work, allowing savings in money, time and labour.
Steel consumption is less because thinner bars are used.
The earthquake resistance of buildings with load-bearing walls is nearly twice that of buildings with load-bearing columns.
Construction time is reduced, as floors can be added over walls without waiting for curing of concrete beams and columns.
No plastering required.
No temporary ‘shuttering’ or ‘form work’ is needed with this method.
Simplicity of design, excellent environmental characteristics, and minimum water use for construction are other advantages.