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Stress ribbon bridge: Modern analogy of ROPE BRIDGE
Features:
Pedestrian bridgesHighly stressed freely suspended pre-stressed tendons Precast or cast in situ deck slab Characterized by successive and complementary smooth curvesCatenary shape or funicular shape
Stress Ribbon Bridge
STRUCTURE
Supports:
Stress Ribbon Bridge
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
Stress Ribbon Bridge
Simple support with constant sectionFlexible saddle arrangement at support
Parabolic hunch arrangement at supportStress ribbon supported by arch
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
Deck:
Stress Ribbon Bridge
Lake Hodges Bridge, USA
FABRICATION
Stress Ribbon Bridge
Leviation Stage: Cables are hanged from supports Pre cast segments are slided over the bearing tendons to desired position Segments are jointed by cast in-situ composite slabs
Stress Ribbon BridgeLeviation Stage:
Typical precast segment on bearing cables
Stress Ribbon BridgeLeviation Stage:Shifting of precast segment on bearing cables
Stress Ribbon BridgeBasic Stage:
Static analysis is done at this stage.After sufficient hardening of joints, post tensioning is done by pre-stressing tendons.Effect of dead load, creep, shrinkage, temperature and pre-stressing are determined.Shape at this stage determines the final sag in the bridge.
Stress Ribbon BridgeService /Ultimate Stage:Analysis of structure for all service loads is done
Multi-spanned Bridges
Stress Ribbon BridgeThese can be of following types: (1)
Concrete or steel columns as intermediate supports
Stress Ribbon Bridge (2)Concrete arch as intermediate supports
Advantages:
Minimal environmental and visual impact Can be erected without falsework or shoringMinimal long-term maintenance is requiredAre highly desirable at place as shown below:
Stress Ribbon Bridge
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
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
Some important bridges in this category:
Stress Ribbon BridgeNameCountryMainSpanRio Colorado BridgeCosta Rica146 mLake Hodges BridgeUSA100.9 mEast Golf Cart BridgeUSA86.9 mRogue River Pedestrian BridgeUSA84.73 mAaresteg MlimattSwitzerland78 mGlacis BridgeGermany76 mAaresteg RupperswilSwitzerland74.05 mPhyllis J. Tilley Memorial BridgeUSA49.5 mKent Messenger Millennium BridgeUnited Kingdom48 mPnt da SuransunsSwitzerland40 m1)2)3)4)5)6)7)8)9)10)
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
Stress Ribbon BridgeReferences: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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