Ms Thesis Presentation


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Ms Thesis Presentation

  1. 1. TopicDYNAMIC HORIZONTAL AND VERTICAL STIFFNESSES OF CAISSON FOUNDATIONS IN HOMOGENOUS SOIL<br />ADVISOR: <br />Prof. Dr. Shahid Ahmad<br />Committee Member:<br />Prof. Dr. Sabanayagam Thevanayagam <br />
  2. 2. Objective<br />To determine the horizontal and vertical stiffness and damping coefficients for caissons.<br />
  3. 3. INTRODUCTION <br />Definition:Caissons, Pier or drilled shafts;<br /><ul><li> Massive Cylindrical Embedded Found, Precast or cast in place concrete with steel reinforcement and steel jacket or casing.
  4. 4. Diameter Range: 2-12 feet.
  5. 5. Depth to Dia ratio: 0.5-4</li></ul>Uses: <br />Bridge foundation elements<br />Foundation components of transmission towers<br />Foundations at marine sites <br />
  6. 6. D<br />B<br />Caisson<br />Schematic Diagram of circular Caisson.<br />
  7. 7. LITERATURE REVIEW<br /><ul><li>G. Gazetas (2005) Lateral Response of Caissons of D/B=1-3 by Winkler model
  8. 8. Varun et al. (2009) Lateral Response of Caissons, D/B=1-6.
  9. 9. Carolin Birk and Behnke (2010) dynamic response of foundations by scaled boundary finite element method.</li></li></ul><li><ul><li> S. Ahmad, A.S.M. Israil and K. Chen (1988)Dynamic stiffness of rigid square and rectangular foundations by DBEM and IBEM.
  10. 10. S. Ahmad, A.K. Rupani (1999) Horizontal impedance of square foundation in layered soil
  11. 11. P. K. Pradhan et al (2004) presented vertical dynamic response of foundation using Cone Model
  12. 12. Iftekhar Anam and Jose M. Roesset (2004) Dynamic stiffness’s of surface foundations</li></li></ul><li><ul><li>Y. Q. Cai et al (2009) Vertical dynamic response of a rigid foundation embedded in poroelastic soil layer.
  13. 13. Artur Pais and Kausel (1988) Approximate formulas for dynamic stiffness’s of rigid foundations.
  14. 14. H. L. Wong and J. E. Luco (1985) Tables of impedance functions for square foundations on layered media.
  15. 15. S. Ahmad and A. Bharadwaj (1991) presented horizontal impedance of embedded strip foundations</li></li></ul><li>CONVERGENCE STUDY OF BOUNDARY ELEMENT DISCRETIZATION AND COMPARISON WITH PUBLISHED RESULTS<br /><ul><li>Poisson’s ration= 0.35
  16. 16. Shear Wave Velocity, Vs=1
  17. 17. Radius of Caisson, B=1
  18. 18. Normalized Elastic Modulus ES=2.7</li></li></ul><li>.<br />Typical discretization pattern for embedded foundation over half-space<br />
  19. 19. .<br />Surface Foundation Boundary Element Discretization (soil-foundation interface)<br />
  20. 20. .<br />Convergence study on free surface discretization for surface foundation<br />
  21. 21. .<br />Convergence study on free surface discretization for caisson, D/B=6<br />
  22. 22. RESULTS, COMPARISON AND DISCUSSIONS<br />Horizontal Static Stiffness of caissons.<br />
  23. 23. .<br />Vertical Static Stiffness of caissons<br />
  24. 24. .<br />Surface Foundation<br />
  25. 25. .<br />Embedded Foundation of D/B=1, Vertical stiffness<br />
  26. 26. .<br />Caissons vertical stiffness at different D/B ratio’s.<br />
  27. 27. .<br />Embedded Foundation, D/B=2.<br />
  28. 28. .<br />Caissons of D/B=4, Horizontal Stiffness.<br />
  29. 29. .<br />Caissons of D/B=6, Horizontal Stiffness.<br />
  30. 30. .<br />Caissons of D/B=8, Horizontal Stiffness.<br />
  31. 31. Conclusion<br />Results for vertical and horizontal stiffness and damping coefficients are available in layered and non-homogeneous media. The results were taken over homogeneous half-space and compared with available results.<br />Thanks<br />