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Cracking In Thin Arch Concrete Dam – Nonlinear Dynamic Structural Analysis

Cracking In Thin Arch Concrete Dam – Nonlinear Dynamic Structural Analysis. Presentation Overview. Investigations Finite Element Model Material Properties Loads Static Analysis Results Dynamic Analysis Results Conclusions. Investigations. Foundation Stability Analysis.

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Cracking In Thin Arch Concrete Dam – Nonlinear Dynamic Structural Analysis

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  1. Cracking In Thin Arch Concrete Dam – Nonlinear Dynamic Structural Analysis

  2. Presentation Overview • Investigations • Finite Element Model • Material Properties • Loads • Static Analysis Results • Dynamic Analysis Results • Conclusions

  3. Investigations • Foundation Stability Analysis

  4. Phase I: Downstream face of Block 3 of the dam located near the left abutment and approximately 85 feet below the crest • Phase II: Entire extent of the crack on the downstream face of the dam including Blocks 2 through 9 • Geophysical Investigations Spectral Analysis of Surface Waves (SASW) Surveys

  5. Concrete Quality vs. Velocity

  6. Finite Element Model Concrete Arch Dam Existing Cracks Overflow Spillway Downstream Reservoir C Block AB Block

  7. Material Properties

  8. Nonlinear Concrete Material Models • Material 159 - uses a damage parameter with a range from zero (indicating no damage) to one (indicating cracking or crushing). This parameter is displayed under the “Effective Plastic Strain” title in the output. The area of damaged concrete is shown in red in the effective plastic strain plots. • Winfrith material - damage is displayed in terms of crack orientation. The orientation matches the orientation a physical crack would take.

  9. Loads • Gravity • Foundation uplift pressure • Temperature • Seismic loads (5k,10k and 50k year) 5,000-year = 0.27g 10,000-year = 0.33g 50,000-year = 0.54g

  10. Gravity Load Application • Dam • Foundation Rock Blocks • Water Dam Foundation Rock Blocks Water

  11. Application of Uplift Pressure • Full Uplift on Both Release Plane and AB Base Plane • Full Uplift on Release Plane and 50% Uplift on AB Base Plane Release Plane Full Uplift AB Base Plane

  12. Temperature Load Application Hot Temperature, Downstream Upstream

  13. Seismic Load Application Free-Field vs Measured Motion

  14. Static Analysis Results Reservoir Water Pressure Applied to the Upstream Face of the Dam

  15. Dynamic Analysis Results Concrete Damage in Arch Dam Under Different Seismic Loadings 5K STU, Winfrith 5K STU, Material 159 10K STU, Material 159 10K STU, Winfrith 50K STU, Material 159 50K STU, Winfrith

  16. Cold Temperature, Winfrith Concrete Damage in Arch Dam Under Different Temperatures Cold Temperature, Material 159 Average Temperature, Winfrith Average Temperature, Material 159 Hot Temperature, Winfrith Hot Temperature, Material 159

  17. Concrete Damage in Arch Dam under Full Uplift and 50% Uplift on AB Base Plane 50% Uplift, Material 159 50% Uplift, Winfrith Full Uplift, Material 159 Full Uplift, Winfrith

  18. Dynamic Analysis Results Foundation Blocks Displacement Apex of AB Block, Node C Foundation, Node B Apex of C Block, Node A

  19. Concrete Damage Caused by Rock Block Displacement Concrete Damage, Small Rock Block Displacement, Material 159 Concrete Damage, Large Rock Block Displacement, Material 159 Concrete Cracks, Small Rock Block Displacement, Winfrith Concrete Cracks, Large Rock Block Displacement, Winfrith

  20. Rock Block Displacement Caused by 50%Uplift and Full Uplift – Material 159 50% Uplift, Material 159 Full Uplift, Material 159 Apex of C Block, Node A Foundation, Node B Apex of AB Block, Node C

  21. Rock Block Displacement Caused by 50%Uplift and Full Uplift – Winfrith 50% Uplift, Winfrith Full Uplift, Winfrith Apex of C Block, Node A Foundation, Node B Apex of AB Block, Node C

  22. Conclusions • Results of the structural analysis indicate the ability for an arch dam to redistribute stresses through arch action even in a damaged state resulting in stability of the dam. • The earthquake magnitude has a significant impact on the stability of both concrete dam and foundation blocks. However atime history of displacements of the dam at various locations show that the displacements stabilize after the seismic events, indicating stability of the arch. • The uplift pressures are critical to understanding the movement of foundation blocks. The arch dam experienced more overall cracking on both upstream and downstream faces under larger uplift pressures. In general, the stability of the concrete dam is related to the magnitude of the uplift pressure at the foundation block. • The analysis showed that the ambient temperature doesn’t have a significant impact either on the arch dam cracking patterns or on the foundation block displacements

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