According to the latest news the death
toll in collapse of a four-storied
building has touched to eight and injured
eighteen in Liaqatabad, Karachi. The
(newly constructed) building collapsed
with a loud blast, trapping people under
its debris.
This is not the first nor the last time
that a newly constructed concrete building
or structure in
Pakistan,
particularly in Karachi, has collapsed
without an apparent reason and killed very
many precious lives. Unfortunately, there
is no institutionalized mechanism
available in Pakistan that, fairly and
independently, could investigate such
avoidable mishaps and puts forward its
recommendations for future improvements.
In general, the
causes of building collapse can be
classified under general headings to
facilitate analysis. These headings are:
-
Bad Design
-
Faulty Construction and Substandard
Material
-
Foundation Failure
-
Extraordinary Loads
-
Unexpected Failure Modes
-
Combination of Causes
Bad design does not mean only errors of
computation, but a failure to take into
account the loads the structure will be
called upon to carry, erroneous theories,
reliance on inaccurate data, ignorance of
the effects of repeated or impulsive
stresses, and improper choice of materials
or misunderstanding of their properties. The
(consultant) engineer is responsible for
these failures, which are created at the
drawing board.
Faulty construction and use of substandard
material has been the most important cause
of structural failure. The (consultant)
engineer is also at fault here, if
inspection has been lax. This includes the
use of salty sand to make concrete, the
substitution of inferior steel for that
specified, bad riveting or even improper
tightening torque of nuts, excessive use of
the drift pin to make holes line up, bad
welds, and other practices well known to the
construction worker.
Even an excellently designed and constructed
structure will not stand on a bad
foundation. Although the structure will
carry its loads, the earth beneath it may
not. The Leaning Tower of Pisa is a famous
example of bad foundations, but there are
many others. The old armory in St. Paul,
Minnesota, sank more than twenty feet into
soft clay, but did not collapse. The
displacements due to bad foundations may
alter the stress distribution significantly.
Extraordinary loads are often natural, such
as repeated heavy rain falls, snowfalls, or
the shaking of an earthquake, or the winds
of a hurricane. A building that is intended
to stand for some years should be able to
meet these challenges. A flimsy flexible
structure may avoid destruction in an
earthquake, while a solid masonry building
would be destroyed.
The Building Code of Pakistan 1986 as
amended for seismic strength in 2007 clearly
specifies the foundation and structural
requirements for a multi-storey building.
Most urban cities have designed their
by-laws in accordance with such requirements
and same goes for the Karachi Building
Control Authority (KBCA). These departments
are composed of thousands of employees and
highly paid specialized staff exclusively
for the purpose of forming and maintaining
building by-laws. Not only these departments
but also are a number of professional bodies
that contribute their expertise into this
important issue.
Yet, on a regular basis, we see such
calamities taking place in our densely
populated residential areas and no one ever
has been held responsible for his/her
murderous actions. One may wonder as if we
are so insensitive and irresponsible towards
public safety or the culprits of such
life-ruining incidents are so strong that
they cannot be brought to justice. It is,
however, time that we act as a responsible
community where safety of life is our
topmost priority and no one is let go with
his/her irresponsible and inhuman actions.
It is time that we use this occurrence to
begin with to hold someone(s) responsible
and accountable of this unpleasant incident
and be given the highest and maximum
possible punishment – even hanging or life
sentencing few may not be a bad idea. This
will not bring back the lives we have
already lost but certainly would save in
future many from being perished without a
minute fault of theirs. |
