Integral Bridges

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INTEGRAL BRIDGES

INTEGRAL BRIDGES

Guided by: Dipu.V.S Lecturer Civil Engg Dept

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INTRODUCTIO

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Integral bridges in simple words, can be defined as bridges without joints. Integral bridges are characterized by monolithic connection between the deck and the substructure (piers and abutments). They span from one

abutment, over intermediate support to the other abutment, without any

joint in the deck. Integral bridges have been constructed all over the world

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WHAT IS AN INTEGRAL

BRIDGE?

Bridges constructed without any

expansion joint (between spans or

between spans and abutments) and

without any bearings are called

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CHARACTERISTICS OF

INTEGRAL BRIDGES

The integral abutment bridge

concept is based on the theory that due to the flexibility of the piling, thermal stresses are transferred to the substructure by way of a rigid connection between the

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MOTIVATION BEHIND INTEGRAL

BRIDGES

 _{To eliminate expansion joints in the deck}

 _{When earthquake forces are predominant or}

when consideration like increased resistance to blasts the integral bridge concept is an

excellent option.

_{Less expensive}

_{Improved durability}

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WHY GO FOR INTEGRAL

BRIDGES?

The expansion joints and bearings, by virtue of their functions are sources of weakness in the bridge and there are many examples of distress in bridges, primarily due to poor performance of these two elements

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 Leaking of expansion joints and seals permit the surface run-off water from roadway

Continual wear and heavy impact from repeated live loads as well as continual stages of movement from expansion and contraction

Impact loadings from heavy commercial vehicles

Elastomeric bearings can split and rupture due to unanticipated movements, or ratchet out of position.

Malfunctioning of bearings can lead to unanticipated structural damage  Joints and bearings are expensive

PROBLEMS OF EXPANSION

JOINTS AND BEARINGS

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INTEGRAL ABUTMENT

The integral abutment is defined

as abutment, which is connected

to the bridge deck without any

movement joint for expansion or

contraction of the deck

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WHY GO FOR INTEGRAL

ABUTMENTS

1.Simple Design

2.Joint less construction 3.Resistance to pressure 4.Rapid construction

5.Ease in constructing embankments

6.No cofferdams

7.Vertical piles (no battered piles) 8.Simple forms

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10.Reduced removal of existing elements 11.Simple beam seats

12.Simplified widening and replacement 13.Lower construction costs and future maintenance costs

14.Improved ride quality 15. It Design efficiency

16.Added redundancy and capacity for catastrophic events

17.Improve Load distribution

18.Enhance protection for weathering steel girders

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PLANNING

CONSIDERATIONS

1.Length of the Structure 2.Climatic Condition

3.Seismic Zone

4.Type of Superstructure 5.Type of Abutments

6.Type of Foundations And Sub-Soil Conditions

7.Geometry of the Structure

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RECOMMENDED QUALITY

IMPROVEMENT PRACTICE FOR

INTEGRAL BRIDGES

_{Develop design criteria or office practices for}

designing integral abutment and join less bridges

_{In extending the remaining service lives of}

existing bridges

_{exchange information in the areas of design,}

construction and maintenance of joints and joint less bridges

_{The decision to install an approach slab should}

be made by the Bridges and Structures Office, with consultation from the Geotechnical group

_{Standardize practice of using sleeper slabs at}

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1. Simplified details for construction

2. Reduced life cycle cost and long term maintenance

3. Improved design efficiency Improved riding quality

4. Added redundancy with improved seismic performance Ease in constructing embankments

5. Elimination of water leakage on critical structural elements

6. Lesser tolerance restriction due to elimination of bearings and expansion joints

7. Faster construction

8. Simplified widening and replacement detail Useful for strengthening of existing bridges

ADVANTAGES OF INTEGRAL

BRIDGES OVER CONVENTIONAL

BRIDGES

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ILLUSTRATIVE

EXAMPLE

1. Dankuni-Palsit Flyover

It is situated at the durgapur Expressway. The span arrangement for the overpass is15m + 2x22.0 m + 15m,continuous over the support. The deck is RC solid slab type integral with the twin piers. The bridge is a joint less bridge without any expansion joint over intermediate piers without any bearings

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2. Kalkaji Flyover

A 150m integral flyover has been provided at the vital T-junction on Ring Road near Kalkaji Temple. The typical five span continuous deck (25m + 30m + 40m + 30m + 25m), has a voided slab reinforced concrete deck with a depth of 1.70m, which was hunched and increased to 2.20m at the piers supporting the 40.0m obligatory main span.

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CONCLUSION

In conclusion, it must be said

that the final product represented by the integral bridge is vastly

superior in performance in

service conditions as compared to traditional bridges with bearings

References

 Alok Bhowmick,2005, Design and detailing of integral

bridges:Suggested guidelines;The Indian Concrete

Journal,79(9),pp 43 – 50.

 Alok Bhowmick,2003,Design and construction of integral

bridges- An innovative concept, The Indian Concrete

Journal,77(7),pp 22 – 35.

 www.nabro.unl.edu  www.cbdg.org

 1. WALLBANK, E. The performance of concrete in bridges – a survey of 200

highway bridges, HMSO, London, 1989, 96pp

 2 NICHOLSON, B. Integral abutments for prestressed beam bridges, British

Precast Concrete, Federation, Leicester, 1998, 84pp.

 difficult to accommodate in design.

 ENGLAND, G., TSANG N. and BUSH, D. Integral bridges: a fundamental

approach to the time–temperature loading problem, Thomas Telford, London,

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