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MA Model

Impact of Foundation Modeling on the Accuracy of Response History Analysis of a 6-story Braced Frame Building. Spring ends constrained to the ground motion history. Foundation walls modeled with the actual stiffness and strength. MA Model.

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MA Model

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  1. Impact of Foundation Modeling on the Accuracy of Response History Analysis of a 6-story Braced Frame Building

  2. Spring ends constrained to the ground motion history Foundation walls modeled with the actual stiffness and strength MA Model

  3. Horizontal nonlinear springs and dashpots connected to the basement wall. Horizontal ground displacements are induced at the free end of each spring and dashpot. Lateral Soil Springs Pedestals Vertical Soil Springs Vertical nonlinear springs and dashpots connecting the top of rigid plate to the bottom of mat foundation.

  4. Footing for the gravity system Lateral Soil Springs

  5. Nonlinear ETABS Model (MA) • Vertical masses included • Eigenvalue analysis does not work • Ritz versus eigenvalue analysis • 50 Ritz vectors are utilized. • The first 9 mode shapes used as Ritz vectors • Subbasement deformations used as Ritz vectors • The gravity load was imposed as a ramp function followed by imposed horizontal and vertical ground displacements • Damping: ??% critical, except for modes ?? and ?? (??%).

  6. Comparison with system identification results

  7. Period Comparisons

  8. Recorded Mathematical Model

  9. Recorded Mathematical Model

  10. Recorded Mathematical Model

  11. Recorded Mathematical Model

  12. Recorded Mathematical Model

  13. Recorded Mathematical Model

  14. Recorded Mathematical Model

  15. Recorded Mathematical Model

  16. Recorded Mathematical Model

  17. Recorded Mathematical Model

  18. Period Comparisons

  19. Approximation #3b:Rigid soil beneath base slab and basement wall springs (tension allowed) with fixed ends INPUT MOTIONS: Free-Field Accelerations applied at the base

  20. Ritz Period Comparison

  21. MA 3B Sensor No. 11

  22. MA 3B Sensor No. 12

  23. MA 3B Sensor No. 13

  24. MA 3B Sensor No. 14

  25. MA 3B Sensor No. 15

  26. Approximation #3c:Rigid soil beneath base slab andno interaction of soil with basement walls INPUT MOTIONS: Same as App. 3d, ug(z=0)

  27. Ritz Period Comparison

  28. MA 3C Sensor No. 11

  29. MA 3C Sensor No. 12

  30. MA 3C Sensor No. 13

  31. MA 3C Sensor No. 14

  32. MA 3C Sensor No. 15

  33. Approximation #3d:Embedded portion of structure neglected and fixed base assumed at ground level INPUT MOTIONS: Free-field ground surface, ug(z=0); θf=0

  34. Ritz Period Comparison

  35. MA 3D Sensor No. 11

  36. MA 3D Sensor No. 12

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