From The Hindu
You can eliminate
beams and columns in construction by using the load-bearing wall technique. Ms.
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.
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| Prof A. R. Santhakumar |
Mr. 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 nearly 25%.
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
Advantages of
load-bearing walls
** 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.
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