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Integral
abutment practices in the United States
Edward
P. Wasserman
In
the United States of America, jointless bridges with
integral abutments have been constructed since the
late 1930s. Through the intervening years, more and
more states have utilised jointless bridge construction
in varying degrees. However, no national standards
or uniform policy regarding permissible bridge lengths,
skews, details or design procedures have ever been
clearly established, although certain general concepts
have become common in practice. This paper will attempt
to capture the state-of-practice in the United States,
but will lean towards practices favoured by the Tennessee
Department of Transportation, an acknowledged leader
in the field.
Integral
abutments for bridges in seismic regions : Californian
practice
Satinder
P. Singh
The
use of integral abutments is common in short-span
bridges. These bridges have performed well in the
regions with low seismicity where total seismic and
thermal movements in the superstructure can be accommodated
at the abutment by proper detailing. In high seismic
zones where superstructure movement due to earthquake
far exceeds that due to temperature variations, bridges
cannot be economically designed to prevent significant
damage to integral abutments. This paper describes
the general design practice in California in the use
of integral abutments for bridges in seismic regions.
Integral
bridges : Examples from quarter century experience
V.V.
Nori, B.S. Joshi and M.N. Patel
Traditionally,
masonry bridges have always been an integral form
of construction - free of joints. However, introduction
of structural steel in combination with masonry piers
lead to introduction of joints with bearings for accommodating
thermal movements. This trend somehow continued for
reinforced concrete bridges with simply supported
spans supported on bearings and each span separated
by expansion joints. There has been considerable innovation
in the type of bearings and expansion joints. However,
the expansion joints still present a major problem
for maintenance and replacement. The benefits of adoption
of monolithic construction without joints is presented
in this paper and the experience gained in the design
and construction of integral form of bridge is described.
All these bridges have shown good performance.
Integral
flyovers in Delhi
Alok
Panday and Mahesh Tandon
The
problem of satisfying both the aesthetics, durability,
maintainability on the one hand and the performance
of bridges and flyovers under seismic conditions on
the other are attracting attention all over the world.
In this regard, integral bridges are becoming more
acceptable because of better knowledge of structural
behaviour of such structural system and realisation
of inherent merits of integral connection between
deck and piers. An integral bridge is a concrete bridge
in which bearings are eliminated and expansion joints
are either eliminated or provided at long distances
in the case of long bridges. The deck slab and piers
are cast monolithic in an integral bridge. This paper
describes the salient features of integral flyovers
located at the intersection of Maa Anandamoyee Marg
(near Kalkajee Temple) and Khegaon Marg (near Panchsheel
Club) on Outer Ring road and Moti Nagar and Punjabi
Bagh Club intersections on Ring Road, New Delhi. These
have become the longest integral flyovers in India.
These flyovers, constructed by Delhi PWD in the heart
of Delhi, would certainly become a landmark in this
historic city.
Design
and construction of elevated viaduct in Dwarka City,
Delhi
Rajan Kataria, Haroon Shaikh and V.V. Nori
The entire
stretch of 6.47-km long viaduct in Dwarka City, Delhi,
is free of bearings, with expansion joints located
typically at 61 m. The viaduct is built using integral
form of construction with precast post-tensioned girders.
The authors describe the salient design features of
the viaduct and some of the issues that were considered
while adopting integral form of design. The construction
methodology of the viaduct is also briefly given.
Design
and detailing of integral bridges: Suggested guidelines
Alok Bhowmick
Integral
bridges have been constructed all over the world including
India and these have proved to be economical and maintenance
free. The author describes the general aspects of
planning, analysis, design and detailing of integral
bridges. In the absence of specific codal guidelines,
an attempt has been made to provide broad design and
detailing guidelines which could be adopted in the
design and construction of such bridges.
Design
of soil loading for integral bridges
George
L. England and Neil C.M. Tsang
In the United
Kingdom, the adoption of an "integral" type
of bridge is recommended for deck lengths shorter
than 60 m. The behaviour of integral bridges is dominated
by cyclical (daily and seasonal) length changes in
the bridge deck and the resulting effect of cyclical
horizontal displacements to the back fill soil of
the abutments. The authors have conducted experiments
to study the escalation of the lateral earth pressures
over the back of the abutments with time. The test
results have illustrated two major effects, namely,
densification and granular flow. The ratcheting flow
behaviour of the back fill soil is highlighted. Finally,
an equation is proposed for lateral soil loading over
the upper half of the abutment wall.
Integral
bridges on the Konkan Railway
S.C.
Gupta, S.D. Limaye, M.K. Gupta, V.L. Dodeja, and V.V.
Nori
This paper
describes the design and construction aspects of some
of the rail bridges in Ratnagiri South sector for
the Konkan Railway Corporation Limited. Unlike most
of the other bridges, these bridges are continuous
reinforced concrete structures without intermediate
expansion joints.
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