Stress ribbon bridge

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These slides present an introduction to Stress-Ribbon Bridges, an innovative bridge design which is aesthetic and easy to fabricate.

Transcript of Stress ribbon bridge

  • 1.Shreya Thusoo 10403EN006 IDD Part IV Department of Civil Engineering IIT (BHU), Varanasi

2. Stress ribbon bridge: Modern analogy of ROPE BRIDGE 3. 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 4. Supports: Stress Ribbon Bridge 5. 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 6. Stress Ribbon Bridge Simple support with constant section Flexible saddle arrangement at support Parabolic hunch arrangement at support Stress ribbon supported by arch 7. 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 8. Deck: Stress Ribbon Bridge Lake Hodges Bridge, USA 9. Stress Ribbon Bridge Leviation Stage: I. Cables are hanged from supports II. Pre cast segments are slided over the bearing tendons to desired position III. Segments are jointed by cast in-situ composite slabs 10. Stress Ribbon Bridge Leviation Stage: Typical precast segment on bearing cables 11. Stress Ribbon Bridge Leviation Stage: Shifting of precast segment on bearing cables 12. 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. 13. Stress Ribbon Bridge Service /Ultimate Stage: Analysis of structure for all service loads is done 14. Stress Ribbon Bridge These can be of following types: (1) Concrete or steel columns as intermediate supports 15. Stress Ribbon Bridge (2) Concrete arch as intermediate supports 16. 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 17. 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 18. 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 19. 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 Mlimatt 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 Pnt da Suransuns Switzerland 40 m 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 20. 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 21. 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