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John H.G. Macdonald

John H.G. Macdonald. Bridge-related research at the University of Bristol. Outline of presentation. BLADE Performance based engineering Site monitoring Dynamics of long-span bridges Other bridge-related research at Bristol Future direction of research.

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John H.G. Macdonald

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  1. John H.G. Macdonald Bridge-related research at the University of Bristol

  2. Outline of presentation • BLADE • Performance based engineering • Site monitoring • Dynamics of long-span bridges • Other bridge-related research at Bristol • Future direction of research

  3. Bristol Laboratories forAdvanced Dynamics Engineering (BLADE) • Due for completion Spring 2004 • £15m grant from Joint Infrastructure Fund • Integration across Engineering Faculty

  4. BLADE Facilities (1) • Earthquake and Large Structures Laboratory • Earthquake shaking table • Strong floor • 5m and 15m high strong walls

  5. BLADE Facilities (2) • Dynamics Laboratory • Advanced Control and Testing Laboratory • Environmental Laboratory • Soil mechanics, Composites, High temperature metals • Heavy Test and Concrete Laboratory • Light Structures Laboratory • Fatigue, Aircraft structures • Modelling and Simulation Laboratory • Workshops and support areas

  6. BLADE Goals • Develop a viable performance-based engineering framework • Develop dynamic sub-structuring and other enabling technologies • Build new knowledge and understanding of systems, non-linear dynamics, materials, control, and risk • Apply the above to real problems and disseminate

  7. BLADE strategic framework Societalinfluences Create and manage system solution (e.g. specific bridge) Develop enabling technologies (e.g. FE analysis, monitoring systems) Underpinningscience Acquire underpinning knowledge (e.g. dynamics, materials, fatigue) Identify stakeholder requirements(e.g. transport link)

  8. Key Performance Indicatortrajectory and envelope Forecast Increasinguncertainty Simulated(physical, computation) • Uncertainty => Risk-based decisions Now Measured Unacceptable KPI KPI Acceptable Time Unacceptable

  9. Process models of structure asset management N.B. Dummy model to demonstrate structure of process model only

  10. Site monitoring of bridges- Second Severn Crossing

  11. Instrumentation on Second Severn Crossing Supported by EPSRC, Severn River Crossing PLCand the Highways Agency

  12. Benefits of site monitoring (of SSC) • Performance measurement and design of specific solutions • Cable vibrations • Vortex-induced deck vibrations • Improved methods of analysis and parameters • Values of damping and wind turbulence • Methods of wind buffeting analysis • Finite Element analysis (static and dynamic) • Developing tools for long-term management • Model updating • Structural Health Monitoring

  13. Damping ratios of cable vibrationsin relation to wind velocity • Theoretical aerodynamic damping matches measured data • Structural damping determined (intercept) • No significant effect of corrosion protection wax

  14. Addition of secondary cables

  15. System identification fromambient vibration measurements • New method allows for multiple vibration modes, loading spectrum and signal processing distortion • Modal parameters identified, including damping • Statistical analysis of accuracy

  16. Comparison of FE and measured mode shapes- first mode of SSC half bridge South elevation West elevation Lines from FE model, crosses from site measurements Cables omitted for clarity Plan • Measured modes used to assess methods of Finite Element modelling (static and dynamic) • Possible extension to model updating and Structural Health Monitoring

  17. Second Severn Crossing vortex-induced vibrations- full-scale and final model measurements • Model corrected for full-scale damping, wind turbulence and vibration mode shape

  18. SSC deck cross-section showing baffles added to inhibit vortex-induced vibrations

  19. Effect of baffles on vortex-induced response of Second Severn Crossing

  20. Second Severn Crossing RMS deck buffeting response near midspan – vertical bending

  21. Spectra of deck vertical displacement

  22. Spectra of deck vertical displacement

  23. Simplified FE / mathematical model Physical Interaction Numerical Dynamic sub-structuring Scaled FE / mathematical model Physical scale model Cable-deck interaction - modelling Prototype

  24. Other bridge-related research at Bristol • Vulnerability analysis, systems and risk • Bridge strengthening with Fibre Reinforced Polymers • Punching shear failure of concrete slabs • Active load control of bridges • Fatigue of structural materials • Local non-intrusive corrosion detection • Multi-support earthquake excitation of long-span bridges • Pedestrian-induced vibrations

  25. Future research directions • Performance-based engineering • Integrating behaviour of system components • Technical / societal • Loading / structural performance(e.g. aerodynamics / non-linear dynamics) • Different structural components(e.g. cable-deck, soil-structure, concrete-FRP) • Dynamic sub-structuring • Structural Health Monitoring

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