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Design
of non-structural elements for buildings: A review
of codal provisions
Goutam
Mondal and Sudhir K Jain
Non-structural
elements of a building are not a part of the main
load-resisting system. Therefore, these are often
neglected from the structural design point of view.
Performance in the past earthquake clearly pointed
out that in view of the absence or inadequacy of design
provisions for non-structural elements and their attachments
it has resulted in poor performance of several life
line buildings. In India too, non-structural damages
are often observed in the earthquakes but are overlooked
owing to the obvious attention to the huge loss of
human lives and structural damage. Moreover, provisions
relating to non-structural element in Indian seismic
codes (IS 1893) are inadequate or practically non-existent.
This paper reviews the design philosophy and design
provisions of several international seismic codes,
and compares design lateral forces recommended in
these codes.
SCC
with crusher dust, fly ash and micro-silica
Praveen
Kumar and S. K. Kaushik
Crushed
stone aggregates are widely used in concrete. In the
process of producing of 20 mm and 10 mm nominal size
aggregates, significant amount of crusher dust and
stone chips in the size range of 2-6 mm are also obtained.
Usually, most of these are not used in concrete. However,
economical and environmental considerations warrant
investigations on their possible use in concrete.
The paper presents test results of an experimental
study to explore the use of crusher dust, stone chips,
and fly ash in self-compacting concrete (SCC). Test
results indicate that SCC with satisfactory strength
can be produced with such marginal materials when
used together with fly ash and micro-silica.
Development
length of reinforcing bars - Need to revise Indian
codal provisions
N.
Subramanian
The
bond between concrete and reinforcement bars is very
important to develop the composite behaviour of reinforced
concrete. Bond strength is influenced by several factors
such as bar diameter, cover of concrete over the bar,
spacing of bars, transverse reinforcement, grade and
confinement of concrete around the bars, aggregates
used in concrete, type of bars and coating applied
on bars, if any, for corrosion prevention. In the
Indian code on concrete structures which was revised
in the year 2000, the provisions regarding development
length remained unchanged. Many of the above parameters
are not considered in the revised code. Hence in this
paper, the Indian codal provisions are compared with
those of American codal provisions (which consider
all these parameters). The effect of high strength
concrete, self consolidating concrete and fibre reinforced
concrete on the development length is also discussed.
A formula for inclusion in the Indian code is also
suggested based on recent research.
Experimental
determination of modulus of elasticity of non-cylindrical
PSC pipes
N.G.
Joshi
Prestressed
concrete (PSC) pipes are widely used for high pressure
water distribution. Although the modulus of elasticity,
E, for both concrete and steel can be independently
assessed with reliability, established tests are not
available for determining the E value of the composite
material. In this paper, the author outlines a test
methodology for calculating modulus of elasticity
of non-cylindrical PSC pipes. The value of coefficient
of permeability is also assessed.
Concrete
repair by electrodeposition
G. Mohankumar
Deposition
of chemical compounds as precipitates on a cracked
surface by electrolysis is tried as a means of repair
of cracked concrete. The effect of electrodeposition
on the corrosion resistance performance of concrete
specimens is quantitatively investigated by laboratory
tests. Reinforced concrete specimens were cast, cracked
under load, partially immersed in different solutions
and a constant current was applied for a specific
period between the rebar as cathode and an external
electrode as anode. Using a standard calomel electrode
the half-cell potential measurements were observed.
Specimens coated with these electrodeposits were again
partially immersed in a corrosive medium of 3.5 percent
NaCl for 30 days in the open atmosphere and the potential
measurements were done once again. The depth of chloride
ion penetration and the weight loss of rebar were
also determined. From the results obtained it was
found that the method of electrodeposition is effective
for filling cracks.
Executive
Summary of the Final Report (Draft) of the National
Construction Safety Team on the Collapses of the World
Trade Center Towers
Reprinted with permission from National Institute
of Standards and Technology, USA
On August
21, 2002, the National Institute of Standards and
Technology (NIST) announced its building and fire
safety investigation of the World Trade Center (WTC)
disaster.1 This WTC Investigation was then conducted
under the authority of the National Construction Safety
Team (NCST) Act, which was signed into law on October
1, 2002.
Water
management in urban centres
The
Indian Buildings Congress organised a national seminar
on "Water management in urban centres" on
July 21-23, 2005 in New Delhi. The theme of the seminar
was significant considering the vast areas affected
by water scarcity. Based on the deliberations, a list
of recommendations were made.
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