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SEMINAR ON STRESS RIBBON

BRIDGE

Shreya Thusoo10403EN006IDD Part IVDepartment of Civil EngineeringIIT (BHU), Varanasi

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INTRODUCTION

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Stress ribbon bridge: Modern analogy of ROPE BRIDGE

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Features:

• Pedestrian bridges

• Highly stressed freely suspended pre-stressed

tendons

• Precast or cast in situ deck slab

• Characterized by successive and complementary

smooth curves

• Catenary shape or funicular shape

Stress Ribbon Bridge

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STRUCTURE

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Supports:

Stress Ribbon Bridge

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Supports:

• Cables are pre-tensioned by anchoring into support structure, hence this region is highly stressed.

• Performance may be improved by construction of: i) flexible saddle

ii) parabolic haunch iii) intermediate arch support

Stress Ribbon Bridge

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Stress Ribbon Bridge

Simple support with constant section

Flexible saddle arrangement at support

Parabolic hunch arrangement at support

Stress ribbon supported by arch

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Deck:

• Might be pre-fabricated or cast in-situ

• Stressed only by normal forces hence might be reduced by waffles

• Integrated with end and intermediate supporting construction so as to work as a composite structure.

Stress Ribbon Bridge

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Deck:Stress Ribbon Bridge

Lake Hodges Bridge, USA

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FABRICATION

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Stress Ribbon Bridge

Leviation Stage:

I. Cables are hanged from supportsII. Pre cast segments are slided over the bearing tendons to

desired positionIII. Segments are jointed by cast in-situ composite slabs

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Stress Ribbon Bridge

Leviation Stage:

Typical precast segment on bearing cables

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Stress Ribbon Bridge

Leviation Stage:

Shifting of precast segment on bearing cables

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Stress Ribbon Bridge

Basic Stage:

I. Static analysis is done at this stage.II. After sufficient hardening of joints, post tensioning is done by

pre-stressing tendons.III. Effect of dead load, creep, shrinkage, temperature and pre-

stressing are determined.IV. Shape at this stage determines the final sag in the bridge.

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Stress Ribbon Bridge

Service /Ultimate Stage:

Analysis of structure for all service loads is done

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MULTI-SPANNED BRIDGES

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Stress Ribbon Bridge

These can be of following types:

(1)

Concrete or steel columns as intermediate supports

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Stress Ribbon Bridge

(2)

Concrete arch as intermediate supports

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CONCLUDING NOTES

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Advantages:

• Minimal environmental and visual impact

• Can be erected without falsework or shoring

• Minimal long-term maintenance is required

• Are highly desirable at place as shown below:

Stress Ribbon Bridge

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Disadvantages:

• Large horizontal forces at the end and intermediate which determines economy of bridge.

Remedy- i) construction of flexible member close to supports

ii) widening of deck at the ends iii) having an arch shaped

intermediate support

• Danger of overturning and oscillations due to high span to width ratio.

Remedy- i) increasing sag ii) proper dynamic analysis

Stress Ribbon Bridge

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Recent advances:

Innovative design uses unidirectional solid carbon fibre cables (TSC).

• Unsupported spans were significantly increased

• Supporting structure was reduced

• Installation time and cost were reduced by over 80%

Stress Ribbon Bridge

World's longest stress ribbon bridge in Cuenca, Spain

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Some important bridges in this category:

Stress Ribbon Bridge

Name Country Main Span

Rio Colorado Bridge Costa Rica 146 m

Lake Hodges Bridge USA 100.9 m

East Golf Cart Bridge USA 86.9 m

Rogue River Pedestrian Bridge  USA 84.73 m

Aaresteg Mülimatt Switzerland 78 m

Glacis Bridge  Germany 76 m

Aaresteg Rupperswil Switzerland 74.05 m

Phyllis J. Tilley Memorial Bridge  USA 49.5 m

Kent Messenger Millennium Bridge United Kingdom 48 m

Pùnt da Suransuns  Switzerland 40 m

1)

2)

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Stress Ribbon Bridge

Jiri Strasky

West Golf Cart Bridge

West Golf Cart Bridge

Sacramento River Trail Pedestrian Bridge

Rogue River Pedestrian Bridge

McLoughlin Boulevard Pedestrian

Bridge

Lake Hodges Bridge

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Stress Ribbon Bridge

References:

1) Strasky,J.- Stress-ribbon pedestrian bridges supported or suspended on arches. Brijuni Islands, 10-14 July 2008.

2) Strasky,J.: Precast stress ribbon pedestrian bridges in Czechoslovakia. PCI JOURNAL, May-June 1987.

3) Strasky,J.: Stress-ribbon pedestrian bridges. International Bridge Conference. Pittsburgh 1999.

4) Nakazawa, Tsutsumi, Yokota- Experimental study on dynamic characteristics of Stress-Ribbon bridge. Ninth world Conference on Earthquake Engineering, JAPAN, Aug 2-9, 1988.

5) Strasky,J.: Stress ribbon and cable supported Pedestrian bridges

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THANK YOU